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2206 KiB

Open AccessArticle

The Optimum Production Method for Quality Improvement of Recycled Aggregates Using Sulfuric Acid and the Abrasion Method

by Haseog Kim, Sangki Park and Hayong Kim

Int. J. Environ. Res. Public Health 2016, 13(8), 769; https://doi.org/10.3390/ijerph13080769 - 29 Jul 2016

Cited by 9 | Viewed by 4606

Abstract

There has been increased deconstruction and demolition of reinforced concrete structures due to the aging of the structures and redevelopment of urban areas resulting in the generation of massive amounts of construction. The production volume of waste concrete is projected to increase rapidly [...] Read more.

There has been increased deconstruction and demolition of reinforced concrete structures due to the aging of the structures and redevelopment of urban areas resulting in the generation of massive amounts of construction. The production volume of waste concrete is projected to increase rapidly over 100 million tons by 2020. However, due to the high cement paste content, recycled aggregates have low density and high absorption ratio. They are mostly used for land reclamation purposes with low added value instead of multiple approaches. This study was performed to determine an effective method to remove cement paste from recycled aggregates by using the abrasion and substituting the process water with acidic water. The aim of this study is to analyze the quality of the recycled fine aggregates produced by a complex method and investigate the optimum manufacturing conditions for recycled fine aggregates based on the design of experiment. The experimental parameters considered were water ratio, coarse aggregate ratio, and abrasion time and, as a result of the experiment, data concerning the properties of recycled sand were obtained. It was found that high-quality recycled fine aggregates can be obtained with 8.57 min of abrasion-crusher time and a recycled coarse aggregate ratio of over 1.5. Full article

(This article belongs to the Special Issue Environmental Systems Engineering)

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2098 KiB

Open AccessArticle

Contamination and Risk Assessment of Heavy Metals in Lake Bed Sediment of a Large Lake Scenic Area in China

by Li Wan, Liang Xu and Yongsheng Fu

Int. J. Environ. Res. Public Health 2016, 13(7), 741; https://doi.org/10.3390/ijerph13070741 - 21 Jul 2016

Cited by 16 | Viewed by 5186

Abstract

The exposure of heavy metals to lake bed sediment of scenic areas may pose risks on aquatic ecosystems and human health, however very few studies on risk assessment have been reported for scenic areas. Accordingly, this study determined concentration levels, and assessed contamination [...] Read more.

The exposure of heavy metals to lake bed sediment of scenic areas may pose risks on aquatic ecosystems and human health, however very few studies on risk assessment have been reported for scenic areas. Accordingly, this study determined concentration levels, and assessed contamination characteristics and risks, of heavy metals in lake bed sediment of National Scenic Areas Songhuahu (NSAS) in China. The concentrations of Zn, Cr, Pb, Ni, and Cu were determined in 29 bed sediment samples. Results showed that the mean values of Zn, Cr, Pb, Ni, and Cu were 92.69, 90.73, 38.29, 46.77, and 49.44 mg/kg, respectively. Pearson correlation coefficients indicated that organic matter was a major factor influencing distribution of heavy metals. The results for enrichment factors indicated that contamination rates and anthropogenic inputs of single heavy metals decreased in the order Cu > Ni > Pb > Cr > Zn; results of Nemerow integrated pollution index suggested that 72.41% of sampling sites were exposed to low to moderately integrated pollution, and 27.59% of sampling sites were exposed to strongly integrated pollution. According to results for potential ecological risk index, ecological risks of single and all the heavy metals in bed sediment from all the sampling sites were low. Human risks were assessed with hazardous quotients, and the results suggested that exposure of heavy metals to bed sediment posed no or little risk to human health, and the pathway of ingestion significantly contributed to human health risks. Full article

(This article belongs to the Special Issue Environmental Systems Engineering)

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3268 KiB

Open AccessArticle

Activated Persulfate Oxidation of Perfluorooctanoic Acid (PFOA) in Groundwater under Acidic Conditions

by Penghua Yin, Zhihao Hu, Xin Song, Jianguo Liu and Na Lin

Int. J. Environ. Res. Public Health 2016, 13(6), 602; https://doi.org/10.3390/ijerph13060602 - 17 Jun 2016

Cited by 53 | Viewed by 8759

Abstract

Perfluorooctanoic acid (PFOA) is an emerging contaminant of concern due to its toxicity for human health and ecosystems. However, successful degradation of PFOA in aqueous solutions with a cost-effective method remains a challenge, especially for groundwater. In this study, the degradation of PFOA [...] Read more.

Perfluorooctanoic acid (PFOA) is an emerging contaminant of concern due to its toxicity for human health and ecosystems. However, successful degradation of PFOA in aqueous solutions with a cost-effective method remains a challenge, especially for groundwater. In this study, the degradation of PFOA using activated persulfate under mild conditions was investigated. The impact of different factors on persulfate activity, including pH, temperature (25 °C–50 °C), persulfate dosage and reaction time, was evaluated under different experimental conditions. Contrary to the traditional alkaline-activated persulfate oxidation, it was found that PFOA can be effectively degraded using activated persulfate under acidic conditions, with the degradation kinetics following the pseudo-first-order decay model. Higher temperature, higher persulfate dosage and increased reaction time generally result in higher PFOA degradation efficiency. Experimental results show that a PFOA degradation efficiency of 89.9% can be achieved by activated persulfate at pH of 2.0, with the reaction temperature of 50 °C, molar ratio of PFOA to persulfate as 1:100, and a reaction time of 100 h. The corresponding defluorination ratio under these conditions was 23.9%, indicating that not all PFOA decomposed via fluorine removal. The electron paramagnetic resonance spectrometer analysis results indicate that both SO₄⁻• and •OH contribute to the decomposition of PFOA. It is proposed that PFOA degradation occurs via a decarboxylation reaction triggered by SO₄⁻•, followed by a HF elimination process aided by •OH, which produces one-CF₂-unit-shortened perfluoroalkyl carboxylic acids (PFCAs, C_n−1F_2n−1COOH). The decarboxylation and HF elimination processes would repeat and eventually lead to the complete mineralization all PFCAs. Full article

(This article belongs to the Special Issue Environmental Systems Engineering)

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959 KiB

Open AccessArticle

A Diffusive Gradient-in-Thin-Film Technique for Evaluation of the Bioavailability of Cd in Soil Contaminated with Cd and Pb

by Peifang Wang, Teng Wang, Yu Yao, Chao Wang, Cui Liu and Ye Yuan

Int. J. Environ. Res. Public Health 2016, 13(6), 556; https://doi.org/10.3390/ijerph13060556 - 2 Jun 2016

Cited by 16 | Viewed by 5188

Abstract

Management of heavy metal contamination requires accurate information about the distribution of bioavailable fractions, and about exchange between the solid and solution phases. In this study, we employed diffusive gradients in thin-films (DGT) and traditional chemical extraction methods (soil solution, HOAc, EDTA, CaCl [...] Read more.

Management of heavy metal contamination requires accurate information about the distribution of bioavailable fractions, and about exchange between the solid and solution phases. In this study, we employed diffusive gradients in thin-films (DGT) and traditional chemical extraction methods (soil solution, HOAc, EDTA, CaCl₂, and NaOAc) to determine the Cd bioavailability in Cd-contaminated soil with the addition of Pb. Two typical terrestrial species (wheat, Bainong AK58; maize, Zhengdan 958) were selected as the accumulation plants. The results showed that the added Pb may enhance the efficiency of Cd phytoextraction which is indicated by the increasing concentration of Cd accumulating in the plant tissues. The DGT-measured Cd concentrations and all the selected traditional extractants measured Cd concentrations all increased with increasing concentration of the addition Pb which were similar to the change trends of the accumulated Cd concentrations in plant tissues. Moreover, the Pearson regression coefficients between the different indicators obtained Cd concentrations and plants uptake Cd concentrations were further indicated significant correlations (p < 0.01). However, the values of Pearson regression coefficients showed the merits of DGT, CaCl₂, and C_sol over the other three methods. Consequently, the in situ measurement of DGT and the ex situ traditional methods could all reflect the inhibition effects between Cd and Pb. Due to the feature of dynamic measurements of DGT, it could be a robust tool to predict Cd bioavaiability in complex contaminated soil. Full article

(This article belongs to the Special Issue Environmental Systems Engineering)

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1380 KiB

Open AccessArticle

Which Factors Determine Metal Accumulation in Agricultural Soils in the Severely Human-Coupled Ecosystem?

by Li Xu, Shanshan Cao, Jihua Wang and Anxiang Lu

Int. J. Environ. Res. Public Health 2016, 13(5), 510; https://doi.org/10.3390/ijerph13050510 - 17 May 2016

Cited by 11 | Viewed by 4569

Abstract

Agricultural soil is typically an important component of urban ecosystems, contributing directly or indirectly to the general quality of human life. To understand which factors influence metal accumulation in agricultural soils in urban ecosystems is becoming increasingly important. Land use, soil type and [...] Read more.

Agricultural soil is typically an important component of urban ecosystems, contributing directly or indirectly to the general quality of human life. To understand which factors influence metal accumulation in agricultural soils in urban ecosystems is becoming increasingly important. Land use, soil type and urbanization indicators all account for considerable differences in metal accumulation in agricultural soils, and the interactions between these factors on metal concentrations were also examined. Results showed that Zn, Cu, and Cd concentrations varied significantly among different land use types. Concentrations of all metals, except for Cd, were higher in calcareous cinnamon soil than in fluvo-aquic soil. Expansion distance and road density were adopted as urbanization indicators, and distance from the urban center was significantly negatively correlated with concentrations of Hg, and negatively correlated with concentrations of Zn, and road density was positively correlated with Cd concentrations. Multivariate analysis of variance indicated that Hg concentration was significantly influenced by the four-way interaction among all factors. The results in this study provide basic data to support the management of agricultural soils and to help policy makers to plan ahead in Beijing. Full article

(This article belongs to the Special Issue Environmental Systems Engineering)

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5475 KiB

Open AccessArticle

A Study on the Preparation of Regular Multiple Micro-Electrolysis Filler and the Application in Pretreatment of Oil Refinery Wastewater

by Ruihong Yang, Jianzhong ZHU, Yingliu Li and Hui Zhang

Int. J. Environ. Res. Public Health 2016, 13(5), 457; https://doi.org/10.3390/ijerph13050457 - 29 Apr 2016

Cited by 19 | Viewed by 6561

Abstract

Through a variety of material screening experiments, Al was selected as the added metal and constituted a multiple micro-electrolysis system of Fe/C/Al. The metal proportion of alloy-structured filler was also analyzed with the best Fe/C/Al ratio of 3:1:1. The regular Fe/C/Al multiple micro-electrolysis [...] Read more.

Through a variety of material screening experiments, Al was selected as the added metal and constituted a multiple micro-electrolysis system of Fe/C/Al. The metal proportion of alloy-structured filler was also analyzed with the best Fe/C/Al ratio of 3:1:1. The regular Fe/C/Al multiple micro-electrolysis fillers were prepared using a high-temperature anaerobic roasting method. The optimum conditions for oil refinery wastewater treated by Fe/C/Al multiple micro-electrolysis were determined to be an initial pH value of 3, reaction time of 80 min, and 0.05 mol/L Na₂SO₄ additive concentration. The reaction mechanism of the treatment of oil refinery wastewater by Fe/C/Al micro-electrolysis was investigated. The process of the treatment of oil refinery wastewater with multiple micro-electrolysis conforms to the third-order reaction kinetics. The gas chromatography–mass spectrometry (GC–MS) used to analyze the organic compounds of the oil refinery wastewater before and after treatment and the Ultraviolet–visible spectroscopy (UV–VIS) absorption spectrum analyzed the degradation process of organic compounds in oil refinery wastewater. The treatment effect of Fe/C/Al multiple micro-electrolysis was examined in the continuous experiment under the optimum conditions, which showed high organic compound removal and stable treatment efficiency. Full article

(This article belongs to the Special Issue Environmental Systems Engineering)

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6227 KiB

Open AccessArticle

Modelling and Analysis of Hydrodynamics and Water Quality for Rivers in the Northern Cold Region of China

by Gula Tang, Yunqiang Zhu, Guozheng Wu, Jing Li, Zhao-Liang Li and Jiulin Sun

Int. J. Environ. Res. Public Health 2016, 13(4), 408; https://doi.org/10.3390/ijerph13040408 - 8 Apr 2016

Cited by 21 | Viewed by 6396

Abstract

In this study, the Mudan River, which is the most typical river in the northern cold region of China was selected as the research object; Environmental Fluid Dynamics Code (EFDC) was adopted to construct a new two-dimensional water quality model for the urban [...] Read more.

In this study, the Mudan River, which is the most typical river in the northern cold region of China was selected as the research object; Environmental Fluid Dynamics Code (EFDC) was adopted to construct a new two-dimensional water quality model for the urban sections of the Mudan River, and concentrations of COD_Cr and NH₃N during ice-covered and open-water periods were simulated and analyzed. Results indicated that roughness coefficient and comprehensive pollutant decay rate were significantly different in those periods. To be specific, the roughness coefficient in the ice-covered period was larger than that of the open-water period, while the decay rate within the former period was smaller than that in the latter. In addition, according to the analysis of the simulated results, the main reasons for the decay rate reduction during the ice-covered period are temperature drop, upstream inflow decrease and ice layer cover; among them, ice sheet is the major contributor of roughness increase. These aspects were discussed in more detail in this work. The model could be generalized to hydrodynamic water quality process simulation researches on rivers in other cold regions as well. Full article

(This article belongs to the Special Issue Environmental Systems Engineering)

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3364 KiB

Open AccessArticle

Concurrent Phosphorus Recovery and Energy Generation in Mediator-Less Dual Chamber Microbial Fuel Cells: Mechanisms and Influencing Factors

by Abdullah Almatouq and Akintunde O. Babatunde

Int. J. Environ. Res. Public Health 2016, 13(4), 375; https://doi.org/10.3390/ijerph13040375 - 29 Mar 2016

Cited by 44 | Viewed by 6081

Abstract

This study investigated the mechanism and key factors influencing concurrent phosphorus (P) recovery and energy generation in microbial fuel cells (MFC) during wastewater treatment. Using a mediator-less dual chamber microbial fuel cell operated for 120 days; P was shown to precipitate as struvite [...] Read more.

This study investigated the mechanism and key factors influencing concurrent phosphorus (P) recovery and energy generation in microbial fuel cells (MFC) during wastewater treatment. Using a mediator-less dual chamber microbial fuel cell operated for 120 days; P was shown to precipitate as struvite when ammonium and magnesium chloride solutions were added to the cathode chamber. Monitoring data for chemical oxygen demand (COD), pH, oxidation reduction potential (ORP) and aeration flow rate showed that a maximum 38% P recovery was achieved; and this corresponds to 1.5 g/L, pH > 8, −550 ± 10 mV and 50 mL/min respectively, for COD, pH_cathode, ORP and cathode aeration flow rate. More importantly, COD and aeration flow rate were shown to be the key influencing factors for the P recovery and energy generation. Results further show that the maximum P recovery corresponds to 72 mW/m² power density. However, the energy generated at maximum P recovery was not the optimum; this shows that whilst P recovery and energy generation can be concurrently achieved in a microbial fuel cell, neither can be at the optimal value. Full article

(This article belongs to the Special Issue Environmental Systems Engineering)

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1155 KiB

Open AccessArticle

Biodegradation of Phenol by Bacteria Strain Acinetobacter Calcoaceticus PA Isolated from Phenolic Wastewater

by Zhenghui Liu, Wenyu Xie, Dehao Li, Yang Peng, Zesheng Li and Shusi Liu

Int. J. Environ. Res. Public Health 2016, 13(3), 300; https://doi.org/10.3390/ijerph13030300 - 9 Mar 2016

Cited by 83 | Viewed by 7992

Abstract

A phenol-degrading bacterium strain PA was successfully isolated from the effluent of petrochemical wastewater. Based on its morphological, physiological and biochemical characteristics, the strain PA was characterized as a Gram-negative, strictly aerobic, nonmotile and short rod-shaped bacterium that utilizes phenol as a sole [...] Read more.

A phenol-degrading bacterium strain PA was successfully isolated from the effluent of petrochemical wastewater. Based on its morphological, physiological and biochemical characteristics, the strain PA was characterized as a Gram-negative, strictly aerobic, nonmotile and short rod-shaped bacterium that utilizes phenol as a sole carbon and energy source. 16S rDNA sequence analysis revealed that this strain is affiliated to Acinetobacter calcoaceticus in the group of Gammaproteobacteria. The strain was efficient in removing 91.6% of the initial 800 mg∙L⁻¹ phenol within 48 h, and had a tolerance of phenol concentration as high as 1700 mg∙L⁻¹. These results indicated that A. calcoaceticus possesses a promising potential in treating phenolic wastewater. Full article

(This article belongs to the Special Issue Environmental Systems Engineering)

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286 KiB

Open AccessArticle

Study on the Effects of Irrigation with Reclaimed Water on the Content and Distribution of Heavy Metals in Soil

by Shibao Lu, Jianhua Wang and Liang Pei

Int. J. Environ. Res. Public Health 2016, 13(3), 298; https://doi.org/10.3390/ijerph13030298 - 8 Mar 2016

Cited by 31 | Viewed by 5372

Abstract

Reclaimed water is an important resource for irrigation, and exploration in making full use of it is an important way to alleviate water shortage. This paper analyzes the effects of irrigation with reclaimed water through field trials on the content and distribution of [...] Read more.

Reclaimed water is an important resource for irrigation, and exploration in making full use of it is an important way to alleviate water shortage. This paper analyzes the effects of irrigation with reclaimed water through field trials on the content and distribution of heavy metals in both tomatoes and the soil. By exploring the effects of reclaimed water after secondary treatment on the content and distribution characteristics of heavy metals in tomatoes and the heavy metal balance in the soil-crop system under different conditions, the study shows that there are no significant differences in the heavy metal content when the quantity of reclaimed water for irrigation varies. Reclaimed water for short-term irrigation does not cause pollution to either the soil environment or the crops. Nor will it cause the accumulation of heavy metals, and the index for the heavy metal content is far below the critical value of the national standard, which indicates that the vegetables irrigated with reclaimed water during their growth turn out to be free of pollutants. The heavy metals brought into the soil by reclaimed water are less than that taken away by the crops. The input and output quantities have only small effects on the heavy metal balance in the soil. This paper provides a reference for the evaluation and safety control of irrigation with reclaimed water. Full article

(This article belongs to the Special Issue Environmental Systems Engineering)

920 KiB

Open AccessArticle

Phosphate Adsorption from Membrane Bioreactor Effluent Using Dowex 21K XLT and Recovery as Struvite and Hydroxyapatite

by Tanjina Nur, Paripurnanda Loganathan, Jaya Kandasamy and Saravanamuthu Vigneswaran

Int. J. Environ. Res. Public Health 2016, 13(3), 277; https://doi.org/10.3390/ijerph13030277 - 3 Mar 2016

Cited by 14 | Viewed by 5519

Abstract

Discharging phosphate through wastewaters into waterways poses a danger to the natural environment due to the serious risks of eutrophication and health of aquatic organisms. However, this phosphate, if economically recovered, can partly overcome the anticipated future scarcity of phosphorus (P) resulting from [...] Read more.

Discharging phosphate through wastewaters into waterways poses a danger to the natural environment due to the serious risks of eutrophication and health of aquatic organisms. However, this phosphate, if economically recovered, can partly overcome the anticipated future scarcity of phosphorus (P) resulting from exhaustion of natural phosphate rock reserves. An experiment was conducted to determine the efficiency of removing phosphate from a membrane bioreactor effluent (pH 7.0–7.5, 20, 35 mg phosphate/L) produced in a water reclamation plant by adsorption onto Dowex 21K XLT ion exchange resin and recover the phosphate as fertilisers. The data satisfactorily fitted to Langmuir adsorption isotherm with a maximum adsorption capacity of 38.6 mg·P/g. The adsorbed phosphate was quantitatively desorbed by leaching the column with 0.1 M NaCl solution. The desorbed phosphate was recovered as struvite when ammonium and magnesium were added at the molar ratio of phosphate, ammonium and magnesium of 1:1:1 at pH 9.5. Phosphate was also recovered from the desorbed solution as hydroxyapatite precipitate by adding calcium hydroxide to the solution at a phosphate to calcium molar ratio of 1:2 at pH 7.0. The P contents of struvite and hydroxyapatite produced were close to those of the respective commercial phosphate fertilisers. Full article

(This article belongs to the Special Issue Environmental Systems Engineering)

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1506 KiB

Open AccessArticle

Bioremediation of Crude Oil Contaminated Desert Soil: Effect of Biostimulation, Bioaugmentation and Bioavailability in Biopile Treatment Systems

by Farid Benyahia and Ahmed Shams Embaby

Int. J. Environ. Res. Public Health 2016, 13(2), 219; https://doi.org/10.3390/ijerph13020219 - 16 Feb 2016

Cited by 43 | Viewed by 8320

Abstract

This work was aimed at evaluating the relative merits of bioaugmentation, biostimulation and surfactant-enhanced bioavailability of a desert soil contaminated by crude oil through biopile treatment. The results show that the desert soil required bioaugmentation and biostimulation for bioremediation of crude oil. The [...] Read more.

This work was aimed at evaluating the relative merits of bioaugmentation, biostimulation and surfactant-enhanced bioavailability of a desert soil contaminated by crude oil through biopile treatment. The results show that the desert soil required bioaugmentation and biostimulation for bioremediation of crude oil. The bioaugmented biopile system led to a total petroleum hydrocarbon (TPH) reduction of 77% over 156 days while the system with polyoxyethylene (20) sorbitan monooleate (Tween 80) gave a 56% decrease in TPH. The biostimulated system with indigenous micro-organisms gave 23% reduction in TPH. The control system gave 4% TPH reduction. The addition of Tween 80 led to a respiration rate that peaked in 48 days compared to 88 days for the bioaugmented system and respiration declined rapidly due to nitrogen depletion. The residual hydrocarbon in the biopile systems studied contained polyaromatics (PAH) in quantities that may be considered as hazardous. Nitrogen was found to be a limiting nutrient in desert soil bioremediation. Full article

(This article belongs to the Special Issue Environmental Systems Engineering)

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2993 KiB

Open AccessArticle

Rainfall–Runoff Simulations to Assess the Potential of SuDS for Mitigating Flooding in Highly Urbanized Catchments

by Daniel Jato-Espino, Susanne M. Charlesworth, Joseba R. Bayon and Frank Warwick

Int. J. Environ. Res. Public Health 2016, 13(1), 149; https://doi.org/10.3390/ijerph13010149 - 21 Jan 2016

Cited by 42 | Viewed by 9278

Abstract

Sustainable Urban Drainage Systems (SuDS) constitute an alternative to conventional drainage when managing stormwater in cities, reducing the impact of urbanization by decreasing the amount of runoff generated by a rainfall event. This paper shows the potential benefits of installing different types of [...] Read more.

Sustainable Urban Drainage Systems (SuDS) constitute an alternative to conventional drainage when managing stormwater in cities, reducing the impact of urbanization by decreasing the amount of runoff generated by a rainfall event. This paper shows the potential benefits of installing different types of SuDS in preventing flooding in comparison with the common urban drainage strategies consisting of sewer networks of manholes and pipes. The impact of these systems on urban water was studied using Geographic Information Systems (GIS), which are useful tools when both delineating catchments and parameterizing the elements that define a stormwater drainage system. Taking these GIS-based data as inputs, a series of rainfall–runoff simulations were run in a real catchment located in the city of Donostia (Northern Spain) using stormwater computer models, in order to compare the flow rates and depths produced by a design storm before and after installing SuDS. The proposed methodology overcomes the lack of precision found in former GIS-based stormwater approaches when dealing with the modeling of highly urbanized catchments, while the results demonstrated the usefulness of these systems in reducing the volume of water generated after a rainfall event and their ability to prevent localized flooding and surcharges along the sewer network. Full article

(This article belongs to the Special Issue Environmental Systems Engineering)

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3776 KiB

Open AccessArticle

Experimental Study on Ultrafine Particle Removal Performance of Portable Air Cleaners with Different Filters in an Office Room

by Huan Ma, Henggen Shen, Tiantian Shui, Qing Li and Liuke Zhou

Int. J. Environ. Res. Public Health 2016, 13(1), 102; https://doi.org/10.3390/ijerph13010102 - 5 Jan 2016

Cited by 23 | Viewed by 6032

Abstract

Size- and time-dependent aerodynamic behaviors of indoor particles, including PM_1.0, were evaluated in a school office in order to test the performance of air-cleaning devices using different filters. In-situ real-time measurements were taken using an optical particle counter. The filtration characteristics [...] Read more.

Size- and time-dependent aerodynamic behaviors of indoor particles, including PM_1.0, were evaluated in a school office in order to test the performance of air-cleaning devices using different filters. In-situ real-time measurements were taken using an optical particle counter. The filtration characteristics of filter media, including single-pass efficiency, volume and effectiveness, were evaluated and analyzed. The electret filter (EE) medium shows better initial removal efficiency than the high efficiency (HE) medium in the 0.3–3.5 μm particle size range, while under the same face velocity, the filtration resistance of the HE medium is several times higher than that of the EE medium. During service life testing, the efficiency of the EE medium decreased to 60% with a total purifying air flow of 25 × 10⁴ m³/m². The resistance curve rose slightly before the efficiency reached the bottom, and then increased almost exponentially. The single-pass efficiency of portable air cleaner (PAC) with the pre-filter (PR) or the active carbon granule filter (CF) was relatively poor. While PAC with the pre-filter and the high efficiency filter (PR&HE) showed maximum single-pass efficiency for PM_1.0 (88.6%), PAC with the HE was the most effective at removing PM_1.0. The enhancement of PR with HE and electret filters augmented the single-pass efficiency, but lessened the airflow rate and effectiveness. Combined with PR, the decay constant of large-sized particles could be greater than for PACs without PR. Without regard to the lifetime, the electret filters performed better with respect to resource saving and purification improvement. A most penetrating particle size range (MPPS: 0.4–0.65 μm) exists in both HE and electret filters; the MPPS tends to become larger after HE and electret filters are combined with PR. These results serve to provide a better understanding of the indoor particle removal performance of PACs when combined with different kinds of filters in school office buildings. Full article

(This article belongs to the Special Issue Environmental Systems Engineering)

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4699 KiB

Open AccessArticle

Advanced Wastewater Treatment Engineering—Investigating Membrane Fouling in both Rotational and Static Membrane Bioreactor Systems Using Empirical Modelling

by Parneet Paul and Franck Anderson Jones

Int. J. Environ. Res. Public Health 2016, 13(1), 100; https://doi.org/10.3390/ijerph13010100 - 5 Jan 2016

Cited by 4 | Viewed by 5481

Abstract

Advanced wastewater treatment using membranes are popular environmental system processes since they allow reuse and recycling. However, fouling is a key limiting factor and so proprietary systems such as Avanti’s RPU-185 Flexidisks membrane bioreactor (MBR) use novel rotating membranes to assist in ameliorating [...] Read more.

Advanced wastewater treatment using membranes are popular environmental system processes since they allow reuse and recycling. However, fouling is a key limiting factor and so proprietary systems such as Avanti’s RPU-185 Flexidisks membrane bioreactor (MBR) use novel rotating membranes to assist in ameliorating it. In earlier research, this rotating process was studied by creating a simulation model based on first principles and traditional fouling mechanisms. In order to directly compare the potential benefits of this rotational system, this follow-up study was carried out using Avanti’s newly developed static (non-rotating) Flexidisks MBR system. The results from operating the static pilot unit were simulated and modelled using the rotational fouling model developed earlier however with rotational switching functions turned off and rotational parameters set to a static mode. The study concluded that a rotating MBR system could increase flux throughput when compared against a similar static system. It is thought that although the slowly rotating spindle induces a weak crossflow shear, it is still able to even out cake build up across the membrane surface, thus reducing the likelihood of localised critical flux being exceeded at the micro level and lessening the potential of rapid trans-membrane pressure increases at the macro level. Full article

(This article belongs to the Special Issue Environmental Systems Engineering)

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Open AccessArticle

Asthma and Wheeze Prevalence among Nursing Professionals in Western Japan: A Cross-Sectional Study

by Jun Kurai, Masanari Watanabe, Hiroyuki Sano, Saeko Torai, Hirokazu Yanase, Tomoaki Funakoshi, Atsuko Fukada, Sachiko Hayakawa, Eiji Shimizu and Hiroya Kitano

Int. J. Environ. Res. Public Health 2015, 12(12), 15459-15469; https://doi.org/10.3390/ijerph121214997 - 4 Dec 2015

Cited by 2 | Viewed by 5256

Abstract

Although adult asthma is attributable to occupational factors, few reports are available on asthma prevalence among health care workers in Japan. The objective of this study was to estimate the prevalence of asthma and wheeze among Japanese nursing professionals. A cross-sectional study was [...] Read more.

Although adult asthma is attributable to occupational factors, few reports are available on asthma prevalence among health care workers in Japan. The objective of this study was to estimate the prevalence of asthma and wheeze among Japanese nursing professionals. A cross-sectional study was conducted by postal survey using a translated version of the European Community Respiratory Health Survey questionnaire from April to June 2013. The analysis included 4634 nursing professionals (257 men and 4377 women) and the overall response rate was 84.8%. The prevalence of current asthma and wheeze were 10.7% (95% confidence interval (CI), 9.9%–11.7%) and 15.6% (95% CI, 14.5%–16.6%), respectively. More than one year of work experience as a nursing professional and more than one year of experience with bed-making tasks were associated with odds ratios (ORs) of 1.95 (95% CI, 1.12–3.39) and 1.64 (95% CI, 1.15–2.23) for wheeze, respectively. Current smoking was significantly associated with the presence of wheeze, with ORs of 2.27 for men (95% CI, 1.11–4.64) and 2.01 for women (95% CI, 1.54–2.64). Among female nurses, latex allergy was associated with wheeze (OR, 1.87; 95% CI, 1.56–2.23), as was body mass index ≥30 (OR, 2.76; 95% CI, 1.65–4.62). This study has provided the prevalence of asthma and wheeze among Japanese nursing professionals. Employment period, bed-making tasks, latex allergy, obesity, and smoking may be risk factors for prevalent wheeze among nursing professionals. Full article

(This article belongs to the Special Issue Environmental Systems Engineering)

1020 KiB

Open AccessArticle

Modeling the Activated Sludge—Thickening Process in Secondary Settlers

by Yuankai Zhang, Xunfei Yin, Zhijiang He, Xiangjun Zhang, Yang Wen and Hongchen Wang

Int. J. Environ. Res. Public Health 2015, 12(12), 15449-15458; https://doi.org/10.3390/ijerph121214996 - 4 Dec 2015

Cited by 7 | Viewed by 5635

Abstract

A single paragraph of about 200 words maximum. For research articles; abstracts should give a pertinent overview of the work. We strongly encourage authors to use the following style of structured abstracts; but without headings: (1) Background: Place the question addressed in a [...] Read more.

A single paragraph of about 200 words maximum. For research articles; abstracts should give a pertinent overview of the work. We strongly encourage authors to use the following style of structured abstracts; but without headings: (1) Background: Place the question addressed in a broad context and highlight the purpose of the study; (2) Methods: Describe briefly the main methods or treatments applied; (3) Results: Summarize the article's main findings; and (4) Conclusion: Indicate the main conclusions or interpretations. The abstract should be an objective representation of the article: it must not contain results which are not presented and substantiated in the main text and should not exaggerate the main conclusions. Full article

(This article belongs to the Special Issue Environmental Systems Engineering)

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953 KiB

Open AccessArticle

Competitive Degradation of Steroid Estrogens by Potassium Permanganate Combined with Ultrasound

by Jing Deng, Kai Tang, Shijun Zhu, Xiaoyan Ma, Kejia Zhang, Yali Song, Xueyan Li, Qingsong Li, Zhenhua Liu and Kejin Zhou

Int. J. Environ. Res. Public Health 2015, 12(12), 15434-15448; https://doi.org/10.3390/ijerph121214995 - 4 Dec 2015

Cited by 8 | Viewed by 5633

Abstract

The occurrence of natural estrogens including estrone (E1), 17β-estradiol (E2), and synthetic 17α-ethinylestradiol (EE2), which can be excreted by both humans and animals, and can enter the aqueous environment along with the discharge of domestic sewage, is a major concern since this may [...] Read more.

The occurrence of natural estrogens including estrone (E1), 17β-estradiol (E2), and synthetic 17α-ethinylestradiol (EE2), which can be excreted by both humans and animals, and can enter the aqueous environment along with the discharge of domestic sewage, is a major concern since this may represent a serious health risk to humans even at extremely trace levels (ng·L⁻¹). Simultaneous degradation of three coexisting steroid estrogens (SEs) in aqueous solutions by coupled ultrasound and KMnO₄ systems (KMnO₄/ultrasound) were investigated to find out whether there is a competitive degradation of multiple contaminants or not. Results indicate that the degradation ratios of target SEs were all more than 50% after 120 min reaction contact, greatly enhanced when compared with the single KMnO₄ (2 mg·L⁻¹) oxidation of E2 (37.0%), EE2 (34.4%), and E1 (34.0%), and the single sonochemical oxidation of E2 (37.1%), EE2 (31.1%), and E1 (29.7%). In the adopted processes, the degradations of SEs fit the first-order kinetic reaction, with different reaction rates. Kinetic parameters revealed there was little difference between coexisting SEs, which means there was almost no competitive degradation. The removal efficiency and degradation rate of SEs in natural water was higher than those in pure water, which suggested that the coupled KMnO₄/ultrasound technology had prospective applications in the removal of complex contaminants in actual drinking water treatment. Full article

(This article belongs to the Special Issue Environmental Systems Engineering)

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Open AccessArticle

Biosorption Potential of Bacillus salmalaya Strain 139SI for Removal of Cr(VI) from Aqueous Solution

by Arezoo Dadrasnia, Kelvin Swee Chuan Wei, Nasser Shahsavari, Mohd Sofian Azirun and Salmah Ismail

Int. J. Environ. Res. Public Health 2015, 12(12), 15321-15338; https://doi.org/10.3390/ijerph121214985 - 3 Dec 2015

Cited by 56 | Viewed by 6620

Abstract

The present study investigated the biosorption capacity of live and dead cells of a novel Bacillus strain for chromium. The optimum biosorption condition was evaluated in various analytical parameters, including initial concentration of chromium, pH, and contact time. The Langmuir isotherm model showed [...] Read more.

The present study investigated the biosorption capacity of live and dead cells of a novel Bacillus strain for chromium. The optimum biosorption condition was evaluated in various analytical parameters, including initial concentration of chromium, pH, and contact time. The Langmuir isotherm model showed an enhanced fit to the equilibrium data. Live and dead biomasses followed the monolayer biosorption of the active surface sites. The maximum biosorption capacity was 20.35 mg/g at 25 °C, with pH 3 and contact time of 50 min. Strain 139SI was an excellent host to the hexavalent chromium. The biosorption kinetics of chromium in the dead and live cells of Bacillus salmalaya (B. salmalaya) 139SI followed the pseudo second-order mechanism. Scanning electron microscopy and fourier transform infrared indicated significant influence of the dead cells on the biosorption of chromium based on cell morphological changes. Approximately 92% and 70% desorption efficiencies were achieved using dead and live cells, respectively. These findings demonstrated the high sorption capacity of dead biomasses of B. salmalaya 139SI in the biosorption process. Thermodynamic evaluation (ΔG⁰, ΔH⁰, and ΔS⁰) indicated that the mechanism of Cr(VI) adsorption is endothermic; that is, chemisorption. Results indicated that chromium accumulation occurred in the cell wall of B. salmalaya 139SI rather than intracellular accumulation. Full article

(This article belongs to the Special Issue Environmental Systems Engineering)

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Open AccessArticle

Meta-Analysis of the Copper, Zinc, and Cadmium Absorption Capacities of Aquatic Plants in Heavy Metal-Polluted Water

by Jing Li, Haixin Yu and Yaning Luan

Int. J. Environ. Res. Public Health 2015, 12(12), 14958-14973; https://doi.org/10.3390/ijerph121214959 - 26 Nov 2015

Cited by 74 | Viewed by 10092

Abstract

The use of aquatic plants for phytoremediation is an important method for restoring polluted ecosystems. We sought to analyze the capacity of different aquatic plant species to absorb heavy metals and to summarize available relevant scientific data on this topic. We present a [...] Read more.

The use of aquatic plants for phytoremediation is an important method for restoring polluted ecosystems. We sought to analyze the capacity of different aquatic plant species to absorb heavy metals and to summarize available relevant scientific data on this topic. We present a meta-analysis of Cu, Zn, and Cd absorption capacities of aquatic plants to provide a scientific basis for the selection of aquatic plants suitable for remediation of heavy-metal pollution. Plants from the Gramineae, Pontederiaceae, Ceratophyllaceae, Typhaceae and Haloragaceae showed relatively strong abilities to absorb these metals. The ability of a particular plant species to absorb a given metal was strongly correlated with its ability to absorb the other metals. However, the absorption abilities varied with the plant organ, with the following trend: roots > stems > leaves. The pH of the water and the life habits of aquatic plants (submerged and emerged) also affect the plant’s ability to absorb elements. Acidic water aids the uptake of heavy metals by plants. The correlation observed between element concentrations in plants with different aquatic life habits suggested that the enrichment mechanism is related to the surface area of the plant exposed to water. We argue that this meta-analysis would aid the selection of aquatic plants suitable for heavy-metal absorption from polluted waters. Full article

(This article belongs to the Special Issue Environmental Systems Engineering)

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Open AccessArticle

Treatment of Actual Chemical Wastewater by a Heterogeneous Fenton Process Using Natural Pyrite

by Liang Sun, Yan Li and Aimin Li

Int. J. Environ. Res. Public Health 2015, 12(11), 13762-13778; https://doi.org/10.3390/ijerph121113762 - 28 Oct 2015

Cited by 28 | Viewed by 6217

Abstract

Wastewater from chemical plants has remarkable antibiotic effects on the microorganisms in traditional biological treatment processes. An enhanced Fenton system catalyzed by natural pyrite was developed to degrade this kind of wastewater. Approximately 30% chemical oxygen demand (COD) was removed within 120 min [...] Read more.

Wastewater from chemical plants has remarkable antibiotic effects on the microorganisms in traditional biological treatment processes. An enhanced Fenton system catalyzed by natural pyrite was developed to degrade this kind of wastewater. Approximately 30% chemical oxygen demand (COD) was removed within 120 min when 50 mmol/L H₂O₂ and 10 g/L natural pyrite were used at initial pH from 1.8 to 7. A BOD₅/COD enhancement efficiency of 210% and an acute biotoxicity removal efficiency of 84% were achieved. The COD removal efficiency was less sensitive to initial pH than was the classic Fenton process. Excessive amounts of pyrite and H₂O₂ did not negatively affect the pyrite Fenton system. The amount of aniline generated indicated that nitrobenzene reduction by pyrite was promoted using a low initial concentration of H₂O₂ (<5 mmol/L). Fluorescence excitation emission matrix analyses illustrated that H₂O₂ facilitated the reduction by natural pyrite of organic molecules containing an electron-withdrawing group to electron-donating group. Thus, the Fenton-like process catalyzed by pyrite can remediate wastewater containing organic pollutants under mild reaction conditions and provide an alternative environmentally friendly method by which to reuse natural pyrite. Full article

(This article belongs to the Special Issue Environmental Systems Engineering)

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Open AccessArticle

A Survey of Soil Enzyme Activities along Major Roads in Beijing: The Implications for Traffic Corridor Green Space Management

by Tianxin Li, Linglong Meng, Uwizeyimana Herman, Zhongming Lu and John Crittenden

Int. J. Environ. Res. Public Health 2015, 12(10), 12475-12488; https://doi.org/10.3390/ijerph121012475 - 8 Oct 2015

Cited by 14 | Viewed by 5778

Abstract

Soil quality is critical to the management of urban green space, in particular, along traffic corridors where traffic-related air pollution is significant. Soil quality can be evaluated by soil enzyme activities, which show quick responses to both natural and anthropogenic disturbances. In this [...] Read more.

Soil quality is critical to the management of urban green space, in particular, along traffic corridors where traffic-related air pollution is significant. Soil quality can be evaluated by soil enzyme activities, which show quick responses to both natural and anthropogenic disturbances. In this study, we investigated three soil enzyme activities (i.e., dehydrogenase, catalase and urease) along the major roads in urban areas of Beijing. Results show the activities of dehydrogenase, catalase and urease in urban samples were 58.8%, 68.2% and 48.5% less than the rural sample, respectively. The content of fluorescent amino acids as indicators of microbial activities was also consistently lower in urban samples than the rural. We observed two times greater exposure of particulate material along the roadsides in urban areas than rural areas. Although traffic air pollutants provide some nutrient sources to stimulate the URE activity, the exposure to traffic-related air pollution leads to the substantial decrease in enzyme activities. There were significant negative correlations for exposure to PM10 with DHA (r = −0.8267, p = 0.0017) and CAT (r = −0.89, p = 0.0002) activities. For the urban soils URE activity increased with the increasing of PM. We conclude that the degraded soil quality can negatively affect the target of developing plants and green spaces along the traffic corridors to mitigate the traffic impact. This study suggests the investigation of integrated strategies to restore the soil quality, reinforce the ecological service functions of green spaces along the traffic corridors and reduce the traffic pollutants. Full article

(This article belongs to the Special Issue Environmental Systems Engineering)

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Open AccessArticle

Water Environmental Capacity Analysis of Taihu Lake and Parameter Estimation Based on the Integration of the Inverse Method and Bayesian Modeling

by Ranran Li and Zhihong Zou

Int. J. Environ. Res. Public Health 2015, 12(10), 12212-12224; https://doi.org/10.3390/ijerph121012212 - 29 Sep 2015

Cited by 10 | Viewed by 4611

Abstract

An integrated approach using the inverse method and Bayesian approach, combined with a lake eutrophication water quality model, was developed for parameter estimation and water environmental capacity (WEC) analysis. The model was used to support load reduction and effective water quality management in [...] Read more.

An integrated approach using the inverse method and Bayesian approach, combined with a lake eutrophication water quality model, was developed for parameter estimation and water environmental capacity (WEC) analysis. The model was used to support load reduction and effective water quality management in the Taihu Lake system in eastern China. Water quality was surveyed yearly from 1987 to 2010. Total nitrogen (TN) and total phosphorus (TP) were selected as water quality model variables. Decay rates of TN and TP were estimated using the proposed approach. WECs of TN and TP in 2011 were determined based on the estimated decay rates. Results showed that the historical loading was beyond the WEC, thus, reduction of nitrogen and phosphorus input is necessary to meet water quality goals. Then WEC and allowable discharge capacity (ADC) in 2015 and 2020 were predicted. The reduction ratios of ADC during these years were also provided. All of these enable decision makers to assess the influence of each loading and visualize potential load reductions under different water quality goals, and then to formulate a reasonable water quality management strategy. Full article

(This article belongs to the Special Issue Environmental Systems Engineering)

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Open AccessArticle

Temporal and Spatial Simulation of Atmospheric Pollutant PM2.5 Changes and Risk Assessment of Population Exposure to Pollution Using Optimization Algorithms of the Back Propagation-Artificial Neural Network Model and GIS

by Ping Zhang, Bo Hong, Liang He, Fei Cheng, Peng Zhao, Cailiang Wei and Yunhui Liu

Int. J. Environ. Res. Public Health 2015, 12(10), 12171-12195; https://doi.org/10.3390/ijerph121012171 - 29 Sep 2015

Cited by 20 | Viewed by 6839

Abstract

PM2.5 pollution has become of increasing public concern because of its relative importance and sensitivity to population health risks. Accurate predictions of PM2.5 pollution and population exposure risks are crucial to developing effective air pollution control strategies. We simulated and predicted the temporal [...] Read more.

PM2.5 pollution has become of increasing public concern because of its relative importance and sensitivity to population health risks. Accurate predictions of PM2.5 pollution and population exposure risks are crucial to developing effective air pollution control strategies. We simulated and predicted the temporal and spatial changes of PM2.5 concentration and population exposure risks, by coupling optimization algorithms of the Back Propagation-Artificial Neural Network (BP-ANN) model and a geographical information system (GIS) in Xi’an, China, for 2013, 2020, and 2025. Results indicated that PM2.5 concentration was positively correlated with GDP, SO₂, and NO₂, while it was negatively correlated with population density, average temperature, precipitation, and wind speed. Principal component analysis of the PM2.5 concentration and its influencing factors’ variables extracted four components that accounted for 86.39% of the total variance. Correlation coefficients of the Levenberg-Marquardt (trainlm) and elastic (trainrp) algorithms were more than 0.8, the index of agreement (IA) ranged from 0.541 to 0.863 and from 0.502 to 0.803 by trainrp and trainlm algorithms, respectively; mean bias error (MBE) and Root Mean Square Error (RMSE) indicated that the predicted values were very close to the observed values, and the accuracy of trainlm algorithm was better than the trainrp. Compared to 2013, temporal and spatial variation of PM2.5 concentration and risk of population exposure to pollution decreased in 2020 and 2025. The high-risk areas of population exposure to PM2.5 were mainly distributed in the northern region, where there is downtown traffic, abundant commercial activity, and more exhaust emissions. A moderate risk zone was located in the southern region associated with some industrial pollution sources, and there were mainly low-risk areas in the western and eastern regions, which are predominantly residential and educational areas. Full article

(This article belongs to the Special Issue Environmental Systems Engineering)

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Open AccessArticle

Remediation of Rare Earth Element Pollutants by Sorption Process Using Organic Natural Sorbents

by Monica Butnariu, Petru Negrea, Lavinia Lupa, Mihaela Ciopec, Adina Negrea, Marius Pentea, Ionut Sarac and Ionel Samfira

Int. J. Environ. Res. Public Health 2015, 12(9), 11278-11287; https://doi.org/10.3390/ijerph120911278 - 10 Sep 2015

Cited by 73 | Viewed by 5811

Abstract

The effects of the sorption of environmental applications by various source materials of natural organic matter, i.e., bone powder, was examined. Sorption capacities and subsequent rare earth element retention characteristics of all metals tested were markedly increased by ionic task-specific. [...] Read more.

The effects of the sorption of environmental applications by various source materials of natural organic matter, i.e., bone powder, was examined. Sorption capacities and subsequent rare earth element retention characteristics of all metals tested were markedly increased by ionic task-specific. In this study, the abilities of three models’ isotherms widely were used for the equilibrium sorption data: Langmuir, Freundlich and Redlich-Peterson. For all studied metal ions the maximum adsorption capacity is close to those experimentally determined. The characteristic parameters for each isotherm and related coefficients of determination have been determined. The experimental data achieved excellent fits within the following isotherms in the order: Langmuir > Redlich-Peterson > Freundlich, based on their coefficient of determination values. The bone powder has developed higher adsorption performance in the removal process of Nd(III), Eu(III), La(III) from aqueous solutions than in the case of the removal process of Cs(I), Sr(II) and Tl(I) from aqueous solutions. The described relationships provide direct experimental evidence that the sorption-desorption properties of bone powder are closely related to their degree of the type of the metal. The results suggest a potential for obtaining efficient and cost-effective engineered natural organic sorbents for environmental applications. Full article

(This article belongs to the Special Issue Environmental Systems Engineering)

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Open AccessArticle

Effects of Humic Acid and Suspended Solids on the Removal of Heavy Metals from Water by Adsorption onto Granular Activated Carbon

by Danious P. Sounthararajah, Paripurnanda Loganathan, Jaya Kandasamy and Saravanamuthu Vigneswaran

Int. J. Environ. Res. Public Health 2015, 12(9), 10475-10489; https://doi.org/10.3390/ijerph120910475 - 27 Aug 2015

Cited by 51 | Viewed by 7444

Abstract

Heavy metals constitute some of the most dangerous pollutants of water, as they are toxic to humans, animals, and aquatic organisms. These metals are considered to be of major public health concern and, therefore, need to be removed. Adsorption is a common physico-chemical [...] Read more.

Heavy metals constitute some of the most dangerous pollutants of water, as they are toxic to humans, animals, and aquatic organisms. These metals are considered to be of major public health concern and, therefore, need to be removed. Adsorption is a common physico-chemical process used to remove heavy metals. Dissolved organic carbon (DOC) and suspended solids (SS) are associated pollutants in water systems that can interact with heavy metals during the treatment process. The interactions of DOC and SS during the removal of heavy metals by granular activated carbon were investigated in batch and fixed-bed column experiments. Batch adsorption studies indicated that Langmuir adsorption maxima for Pb, Cu, Zn, Cd, and Ni at pH 6.5 were 11.9, 11.8, 3.3, 2.0, and 1.8 mg/g, respectively. With the addition of humic acid (HA) (DOC representative), they were 7.5, 3.7, 3.2, 1.6, and 2.5 mg/g, respectively. In the column experiment, no breakthrough (complete removal) was obtained for Pb and Cu, but adding HA provided a breakthrough in removing these metals. For Zn, Cd and Ni, this breakthrough occurred even without HA being added. Adding kaolinite (representative of SS) had no effect on Pb and Cu, but it did on the other metals. Full article

(This article belongs to the Special Issue Environmental Systems Engineering)

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Open AccessArticle

Biosurfactant Production by Bacillus salmalaya for Lubricating Oil Solubilization and Biodegradation

by Arezoo Dadrasnia and Salmah Ismail

Int. J. Environ. Res. Public Health 2015, 12(8), 9848-9863; https://doi.org/10.3390/ijerph120809848 - 19 Aug 2015

Cited by 56 | Viewed by 7541

Abstract

This study investigated the capability of a biosurfactant produced by a novel strain of Bacillus salmalaya to enhance the biodegradation rates and bioavailability of organic contaminants. The biosurfactant produced by cultured strain 139SI showed high physicochemical properties and surface activity in the selected [...] Read more.

This study investigated the capability of a biosurfactant produced by a novel strain of Bacillus salmalaya to enhance the biodegradation rates and bioavailability of organic contaminants. The biosurfactant produced by cultured strain 139SI showed high physicochemical properties and surface activity in the selected medium. The biosurfactant exhibited a high emulsification index and a positive result in the drop collapse test, with the results demonstrating the wetting activity of the biosurfactant and its potential to produce surface-active molecules. Strain 139SI can significantly reduce the surface tension (ST) from 70.5 to 27 mN/m, with a critical micelle concentration of 0.4%. Moreover, lubricating oil at 2% (v/v) was degraded on Day 20 (71.5). Furthermore, the biosurfactant demonstrated high stability at different ranges of salinity, pH, and temperature. Overall, the results indicated the potential use of B. salmalaya 139SI in environmental remediation processes. Full article

(This article belongs to the Special Issue Environmental Systems Engineering)

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Study on the Adsorption Capacities for Airborne Particulates of Landscape Plants in Different Polluted Regions in Beijing (China)

by Wei-Kang Zhang, Bing Wang and Xiang Niu

Int. J. Environ. Res. Public Health 2015, 12(8), 9623-9638; https://doi.org/10.3390/ijerph120809623 - 14 Aug 2015

Cited by 41 | Viewed by 6507

Abstract

Urban landscape plants are an important component of the urban ecosystem, playing a significant role in the adsorption of airborne particulates and air purification. In this study, six common landscape plants in Beijing were chosen as research subjects, and the adsorption capacities for [...] Read more.

Urban landscape plants are an important component of the urban ecosystem, playing a significant role in the adsorption of airborne particulates and air purification. In this study, six common landscape plants in Beijing were chosen as research subjects, and the adsorption capacities for each different plant leaf and the effects of the leaf structures for the adsorption capacities for particulates were determined. Preliminary results show that needle-leaved tree species adsorbed more airborne particulates than broad-leaved tree species for the same leaf area. Pinus tabuliformis exhibits the highest adsorption capacity, at 3.89 ± 0.026 μg·cm⁻², almost two times as much as that of Populus tomentosa (2.00 ± 0.118 μg·cm⁻²). The adsorption capacities for PM₁₀ of the same tree species leaves, in different polluted regions had significant differences, and the adsorption capacities for PM₁₀ of the tree species leaf beside the Fifth Ring Road were higher than those of the tree species leaves in the Botanical Garden, although the adsorption capacities for PM_2.5 of the same tree species in different polluted regions had no significant differences. By determining the soluble ion concentrations of the airborne particulates in two regions, it is suggested that the soluble ion concentrations of PM₁₀ in the atmosphere in the Botanical Garden and beside the Fifth Ring Road have significant differences, while those of PM_2.5 in the atmosphere had no significant differences. In different polluted regions there are significant adaptive changes to the leaf structures, and when compared with slightly polluted region, in the seriously polluted region the epidermis cells of the plant leaves shrinked, the surface textures of the leaves became rougher, and the stomas’ frequency and the pubescence length increased. Even though the plant leaves exposed to the seriously polluted region changed significantly, these plants can still grow normally and healthily. Full article

(This article belongs to the Special Issue Environmental Systems Engineering)

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Open AccessArticle

Factors Contributing to Hypoxia in the Minjiang River Estuary, Southeast China

by Peng Zhang, Yong Pang, Hongche Pan, Chengchun Shi, Yawen Huang and Jianjian Wang

Int. J. Environ. Res. Public Health 2015, 12(8), 9357-9374; https://doi.org/10.3390/ijerph120809357 - 11 Aug 2015

Cited by 24 | Viewed by 7095

Abstract

Dissolved oxygen (DO) is not only a fundamental parameter of coastal water quality, but also an indication of organics decomposed in water and their degree of eutrophication. There has been a concern about the deterioration of dissolved oxygen conditions in the Minjiang River [...] Read more.

Dissolved oxygen (DO) is not only a fundamental parameter of coastal water quality, but also an indication of organics decomposed in water and their degree of eutrophication. There has been a concern about the deterioration of dissolved oxygen conditions in the Minjiang River Estuary, the longest river in Fujian Province, Southeast China. In this study, the syntheses effects on DO was analyzed by using a four year time series of DO concentration and ancillary parameters (river discharge, water level, and temperature) from the Fuzhou Research Academy of Environmental Sciences, at three automated stations along the Minjiang River Estuary. Hypoxia occurred exclusively in the fluvial sections of the estuary during the high temperature and low river discharge period and was remarkably more serious in the river reach near the large urban area of Fuzhou. Enhancement of respiration by temperature and discharge of domestic sewage and industrial wastewater, versus regeneration of waters and dilution of pollutant concentration with increased river discharge, which regarded as the dominant antagonist processes that controlled the appearance of seasonal hypoxia. During the high temperature and the drought period, minimal mainstream flow above 700 m³s⁻¹, reduction of pollutants and forbidding sediment dredging in the South Channel should be guaranteed for strong supports on water quality management and drinking water source protection. Full article

(This article belongs to the Special Issue Environmental Systems Engineering)

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Assessing the Variability of Heavy Metal Concentrations in Liquid-Solid Two-Phase and Related Environmental Risks in the Weihe River of Shaanxi Province, China

by Jinxi Song, Xiaogang Yang, Junlong Zhang, Yongqing Long, Yan Zhang and Taifan Zhang

Int. J. Environ. Res. Public Health 2015, 12(7), 8243-8262; https://doi.org/10.3390/ijerph120708243 - 17 Jul 2015

Cited by 46 | Viewed by 6429 | Correction

Abstract

Accurate estimation of the variability of heavy metals in river water and the hyporheic zone is crucial for pollution control and environmental management. The biotoxicities and potential ecological risks of heavy metals (Cu, Zn, Pb, Cd) in a solid-liquid two-phase system were estimated [...] Read more.

Accurate estimation of the variability of heavy metals in river water and the hyporheic zone is crucial for pollution control and environmental management. The biotoxicities and potential ecological risks of heavy metals (Cu, Zn, Pb, Cd) in a solid-liquid two-phase system were estimated using the Geo-accumulation Index, Potential Ecological Risk Assessment and Quality Standard Index methods in the Weihe River of Shaanxi Province, China. Water and sediment samples were collected from five study sites during spring, summer and winter, 2013. The dominant species in the streambed sediments were chironomids and flutter earthworm, whose bioturbation mainly ranged from 0 to 20 cm. The concentrations of heavy metals in surface water and pore water varied obviously in spring and summer. The degrees of concentration of Cu and Cd in spring and summer were higher than the U.S. water quality Criteria Maximum Concentrations. Furthermore, the biotoxicities of Pb and Zn demonstrated season-spatial variations. The concentrations of Cu, Zn, Pb and Cd in spring and winter were significantly higher than those in summer, and the pollution levels also varied obviously in different layers of the sediments. Moreover, the pollution level of Cd was the most serious, as estimated by all three assessment methods. Full article

(This article belongs to the Special Issue Environmental Systems Engineering)

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Mineralization and Detoxification of the Carcinogenic Azo Dye Congo Red and Real Textile Effluent by a Polyurethane Foam Immobilized Microbial Consortium in an Upflow Column Bioreactor

by Harshad Lade, Sanjay Govindwar and Diby Paul

Int. J. Environ. Res. Public Health 2015, 12(6), 6894-6918; https://doi.org/10.3390/ijerph120606894 - 16 Jun 2015

Cited by 119 | Viewed by 11488

Abstract

A microbial consortium that is able to grow in wheat bran (WB) medium and decolorize the carcinogenic azo dye Congo red (CR) was developed. The microbial consortium was immobilized on polyurethane foam (PUF). Batch studies with the PUF-immobilized microbial consortium showed complete removal [...] Read more.

A microbial consortium that is able to grow in wheat bran (WB) medium and decolorize the carcinogenic azo dye Congo red (CR) was developed. The microbial consortium was immobilized on polyurethane foam (PUF). Batch studies with the PUF-immobilized microbial consortium showed complete removal of CR dye (100 mg·L⁻¹) within 12 h at pH 7.5 and temperature 30 ± 0.2 °C under microaerophilic conditions. Additionally, 92% American Dye Manufactureing Institute (ADMI) removal for real textile effluent (RTE, 50%) was also observed within 20 h under the same conditions. An upflow column reactor containing PUF-immobilized microbial consortium achieved 99% CR dye (100 mg·L⁻¹) and 92% ADMI removal of RTE (50%) at 35 and 20 mL·h^−l flow rates, respectively. Consequent reduction in TOC (83 and 79%), COD (85 and 83%) and BOD (79 and 78%) of CR dye and RTE were also observed, which suggested mineralization. The decolorization process was traced to be enzymatic as treated samples showed significant induction of oxidoreductive enzymes. The proposed biodegradation pathway of the dye revealed the formation of lower molecular weight compounds. Toxicity studies with a plant bioassay and acute tests indicated that the PUF-immobilized microbial consortium favors detoxification of the dye and textile effluents. Full article

(This article belongs to the Special Issue Environmental Systems Engineering)

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Comparison of Land, Water, and Energy Requirements of Lettuce Grown Using Hydroponic vs. Conventional Agricultural Methods

by Guilherme Lages Barbosa, Francisca Daiane Almeida Gadelha, Natalya Kublik, Alan Proctor, Lucas Reichelm, Emily Weissinger, Gregory M. Wohlleb and Rolf U. Halden

Int. J. Environ. Res. Public Health 2015, 12(6), 6879-6891; https://doi.org/10.3390/ijerph120606879 - 16 Jun 2015

Cited by 385 | Viewed by 60391

Abstract

The land, water, and energy requirements of hydroponics were compared to those of conventional agriculture by example of lettuce production in Yuma, Arizona, USA. Data were obtained from crop budgets and governmental agricultural statistics, and contrasted with theoretical data for hydroponic lettuce production [...] Read more.

The land, water, and energy requirements of hydroponics were compared to those of conventional agriculture by example of lettuce production in Yuma, Arizona, USA. Data were obtained from crop budgets and governmental agricultural statistics, and contrasted with theoretical data for hydroponic lettuce production derived by using engineering equations populated with literature values. Yields of lettuce per greenhouse unit (815 m²) of 41 ± 6.1 kg/m²/y had water and energy demands of 20 ± 3.8 L/kg/y and 90,000 ± 11,000 kJ/kg/y (±standard deviation), respectively. In comparison, conventional production yielded 3.9 ± 0.21 kg/m²/y of produce, with water and energy demands of 250 ± 25 L/kg/y and 1100 ± 75 kJ/kg/y, respectively. Hydroponics offered 11 ± 1.7 times higher yields but required 82 ± 11 times more energy compared to conventionally produced lettuce. To the authors’ knowledge, this is the first quantitative comparison of conventional and hydroponic produce production by example of lettuce grown in the southwestern United States. It identified energy availability as a major factor in assessing the sustainability of hydroponics, and it points to water-scarce settings offering an abundance of renewable energy (e.g., from solar, geothermal, or wind power) as particularly attractive regions for hydroponic agriculture. Full article

(This article belongs to the Special Issue Environmental Systems Engineering)

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Open AccessArticle

Effects of Varying Particle Sizes and Different Types of LDH-Modified Anthracite in Simulated Test Columns for Phosphorous Removal

by Xiangling Zhang, Qiaozhen Chen, Lu Guo, Hualing Huang and Chongying Ruan

Int. J. Environ. Res. Public Health 2015, 12(6), 6788-6800; https://doi.org/10.3390/ijerph120606788 - 16 Jun 2015

Cited by 14 | Viewed by 5959

Abstract

A comparative study was carried out for the removal of phosphorus in simulated unplanted vertical-flow constructed wetlands with different layered double hydroxide (LDHs) coated anthracite substrates. Three particle sizes of anthracites were selected and modified separately with nine kinds of LDH coating. The [...] Read more.

A comparative study was carried out for the removal of phosphorus in simulated unplanted vertical-flow constructed wetlands with different layered double hydroxide (LDHs) coated anthracite substrates. Three particle sizes of anthracites were selected and modified separately with nine kinds of LDH coating. The simulated substrates test columns loaded with the original and modified anthracites were constructed to treat the contaminated water. For the medium and large particle size modified anthracite substrates, the purification effects of total phosphorus, total dissolved phosphorus and phosphate were improved by various degrees, and the purification effect of the medium particle size anthracite is better than that of the large size one. The medium size anthracite modified by ZnCo-LDHs had optimal performance with average removal efficiencies of total phosphorus, total dissolved phosphorus and phosphate reaching 95%, 95% and 98%, respectively. The maximum adsorption capacity on ZnCo-LDHs and ZnAl-LDHs modified medium sizes anthracites were 65.79 (mg/kg) and 48.78 (mg/kg), respectively. In comparison, the small size anthracite is not suitable for LDHs modification. Full article

(This article belongs to the Special Issue Environmental Systems Engineering)

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Open AccessArticle

Predicting the Probability of Failure of Cementitious Sewer Pipes Using Stochastic Finite Element Method

by Amir M. Alani and Asaad Faramarzi

Int. J. Environ. Res. Public Health 2015, 12(6), 6641-6656; https://doi.org/10.3390/ijerph120606641 - 10 Jun 2015

Cited by 16 | Viewed by 6303

Abstract

In this paper, a stochastic finite element method (SFEM) is employed to investigate the probability of failure of cementitious buried sewer pipes subjected to combined effect of corrosion and stresses. A non-linear time-dependant model is used to determine the extent of concrete corrosion. [...] Read more.

In this paper, a stochastic finite element method (SFEM) is employed to investigate the probability of failure of cementitious buried sewer pipes subjected to combined effect of corrosion and stresses. A non-linear time-dependant model is used to determine the extent of concrete corrosion. Using the SFEM, the effects of different random variables, including loads, pipe material, and corrosion on the remaining safe life of the cementitious sewer pipes are explored. A numerical example is presented to demonstrate the merit of the proposed SFEM in evaluating the effects of the contributing parameters upon the probability of failure of cementitious sewer pipes. The developed SFEM offers many advantages over traditional probabilistic techniques since it does not use any empirical equations in order to determine failure of pipes. The results of the SFEM can help the concerning industry (e.g., water companies) to better plan their resources by providing accurate prediction for the remaining safe life of cementitious sewer pipes. Full article

(This article belongs to the Special Issue Environmental Systems Engineering)

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Bioaugmentation: An Emerging Strategy of Industrial Wastewater Treatment for Reuse and Discharge

by Alexis Nzila, Shaikh Abdur Razzak and Jesse Zhu

Int. J. Environ. Res. Public Health 2016, 13(9), 846; https://doi.org/10.3390/ijerph13090846 - 25 Aug 2016

Cited by 162 | Viewed by 14765

Abstract

A promising long-term and sustainable solution to the growing scarcity of water worldwide is to recycle and reuse wastewater. In wastewater treatment plants, the biodegradation of contaminants or pollutants by harnessing microorganisms present in activated sludge is one of the most important strategies [...] Read more.

A promising long-term and sustainable solution to the growing scarcity of water worldwide is to recycle and reuse wastewater. In wastewater treatment plants, the biodegradation of contaminants or pollutants by harnessing microorganisms present in activated sludge is one of the most important strategies to remove organic contaminants from wastewater. However, this approach has limitations because many pollutants are not efficiently eliminated. To counterbalance the limitations, bioaugmentation has been developed and consists of adding specific and efficient pollutant-biodegrading microorganisms into a microbial community in an effort to enhance the ability of this microbial community to biodegrade contaminants. This approach has been tested for wastewater cleaning with encouraging results, but failure has also been reported, especially during scale-up. In this review, work on the bioaugmentation in the context of removal of important pollutants from industrial wastewater is summarized, with an emphasis on recalcitrant compounds, and strategies that can be used to improve the efficiency of bioaugmentation are also discussed. This review also initiates a discussion regarding new research areas, such as nanotechnology and quorum sensing, that should be investigated to improve the efficiency of wastewater bioaugmentation. Full article

(This article belongs to the Special Issue Environmental Systems Engineering)

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A Review of the Water and Energy Sectors and the Use of a Nexus Approach in Abu Dhabi

by Parneet Paul, Ameena Kulaib Al Tenaiji and Nuhu Braimah

Int. J. Environ. Res. Public Health 2016, 13(4), 364; https://doi.org/10.3390/ijerph13040364 - 25 Mar 2016

Cited by 37 | Viewed by 7993

Abstract

Rapid population increase coupled with urbanization and industrialization has resulted in shortages of water in the Middle East. This situation is further exacerbated by global climate change due to greenhouse gas emissions. Recent research advocates that solutions to the global water security and [...] Read more.

Rapid population increase coupled with urbanization and industrialization has resulted in shortages of water in the Middle East. This situation is further exacerbated by global climate change due to greenhouse gas emissions. Recent research advocates that solutions to the global water security and scarcity crisis must involve water–energy nexus approaches. This means adopting policies and strategies that harmonize these inter-related sectors to minimize environmental impact while maximizing human benefit. In the case of Abu Dhabi, when designing and locating oil/gas refineries and associated power generation facilities, previous relevant decisions were based on simple economic and geographical grounds, such as nearness to oil rigs, pipelines, existing industries and port facilities, etc. The subsequent design and location of water abstraction and treatment works operated by the waste heat from these refining and/or power generation processes was catered for as an afterthought, meaning that there is now a mismatch between the water and energy supplies and demands. This review study was carried out to show how Abu Dhabi is trying now to integrate its water–energy sectors using a nexus approach so that future water/power infrastructure is designed optimally and operated in harmony, especially in regard to future demand. Based upon this review work, some recommendations are made for designers and policy makers alike to bolster the nexus approach that Abu Dhabi is pursuing. Full article

(This article belongs to the Special Issue Environmental Systems Engineering)

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