Frontiers of Environmental Science & Engineering

ISSN 2095-2201

ISSN 2095-221X(Online)

CN 10-1013/X

Postal Subscription Code 80-973

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Oxidant or catalyst for oxidation? The role of manganese oxides in the activation of peroxymonosulfate (PMS)
Jianzhi Huang, Huichun Zhang
Front. Environ. Sci. Eng.    2019, 13 (5): 65-null.
Abstract   HTML   PDF (371KB)

Manganese oxides (MnOx) have been demonstrated to be effective materials to activate Oxone (i.e., PMS) to degrade various contaminants. However, the contribution of direct oxidation by MnOx to the total contaminant degradation under acidic conditions was often neglected in the published work, which has resulted in different and even conflicting interpretations of the reaction mechanisms. Here, the role of MnOx (as both oxidants and catalysts) in the activation of Oxone was briefly discussed. The findings offered new insights into the reaction mechanisms in PMS-MnOx and provided a more accurate approach to examine contaminant degradation for water/wastewater treatment.

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Combined Fenton process and sulfide precipitation for removal of heavy metals from industrial wastewater: Bench and pilot scale studies focusing on in-depth thallium removal
Huosheng Li, Hongguo Zhang, Jianyou Long, Ping Zhang, Yongheng Chen
Front. Environ. Sci. Eng.    2019, 13 (4): 49-.
Abstract   HTML   PDF (2023KB)

Addition of alkali to pH 10 is effective for precipitation of precipitable metals.

Fenton treatment is effective for substantial removal of Tl, Cd, Cu, Pb, and Zn.

Sulfide precipitation is a final step for removal of trace Tl, Cd, Cu, Pb, and Zn.

Bench and pilot studies demonstrated the effectiveness of this combined technique.

Thallium (Tl) in industrial wastewater is a public health concern due to its extremely high toxicity. However, there has been limited research regarding Tl removal techniques and engineering practices to date. In this investigation, bench and pilot studies on advanced treatment of industrial wastewater to remove Tl to a trace level were conducted. The treatment process involved a combination of hydroxide precipitation, Fenton oxidation, and sulfide precipitation. While hydroxide precipitation was ineffective for Tl+ removal, it enabled the recovery of approximately 70%–80% of Zn as Zn hydroxide in alkaline conditions. The Fenton process provided good Tl removal (>95%) through oxidation and precipitation. Tl was then removed to trace levels (<1.0 µg/L) via sulfide precipitation. Effective removal of other heavy metals was also achieved, with Cd<13.4 µg/L, Cu<39.6 µg/L, Pb<5.32 µg/L, and Zn<357 µg/L detected in the effluent. X-ray photoelectron spectroscopy indicated that Tl2S precipitate formed due to sulfide precipitation. Other heavy metals were removed via the formation of metal hydroxides during hydroxide precipitation and Fenton treatment, as well as via the formation of metal sulfides during sulfide precipitation. This combined process provides a scalable approach for the in-depth removal of Tl and other heavy metals from industrial wastewater.

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Cited: Crossref(6) WebOfScience(5)
Influence of hydraulic retention time on behavior of antibiotics and antibiotic resistance genes in aerobic granular reactor treating biogas slurry
Jie Liao, Chaoxiang Liu, Lin Liu, Jie Li, Hongyong Fan, Jiaqi Ye, Zhichao Zeng
Front. Environ. Sci. Eng.    2019, 13 (3): 31-.
Abstract   HTML   PDF (1385KB)

Longer HRT can enhance degradation rate of sulfamethoxazole in granular reactor.

Longer HRT can reduce accumulated concentrations of TCs and QNs in sludge.

Longer HRT may have increased relative abundances of ARGs in aerobic granules.

The behavior of antibiotics and the corresponding resistance genes in aerobic granular reactors for treating biogas slurry under different hydraulic retention times (10.7 h, R1; 8 h, R2) was investigated in this study. The results indicated that the hydraulic retention time could affect the effluent concentrations and removal efficiencies of sulfonamides. The average removal rates of tetracyclines, fluoroquinolones, and sulfonamides were 63%, 46%, and 90% in R1, and 62%, 46%, and 86% in R2, respectively. Although the removal efficiencies of tetracyclines and fluoroquinolones were similar in both reactors, the respective accumulated concentrations of tetracyclines and fluoroquinolones in R1 were 7.00 and 11.15 µg/g SS, which were lower than those in R2 (8.92 and 13.37 µg/g SS, respectively). The difference in the relative abundance of target antibiotic resistance genes between both reactors was not significant, yet the average relative abundances of all target resistance genes in R1 were higher than those in R2 after 45 days of operation. The results of this study suggested that a longer hydraulic retention time could enhance the antibiotic removal ability of aerobic granular sludge, yet it may also increase the risk of surplus sludge utilization from a resistance genes point of view.

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Effective removal of Cd2+ and Pb2+ pollutants from wastewater by dielectrophoresis-assisted adsorption
Qinghao Jin, Chenyang Cui, Huiying Chen, Jing Wu, Jing Hu, Xuan Xing, Junfeng Geng, Yanhong Wu
Front. Environ. Sci. Eng.    2019, 13 (2): 16-.
Abstract   HTML   PDF (353KB)

Dielectrophoresis (DEP) process could enhance the removal the Cd2+ and Pb2+ with less absorbent.

The removal rates of both Cd2+ and Pb2+ increased with the increase of voltage.

The overall removal rate of Cd2+ and Pb2+ in the binary system is higher than that of Cd2+ or Pb2+ in the single system.

DEP could cause considerable changes of the bentonite particles in both surface morphology and microstructure.

Dielectrophoresis (DEP) was combined with adsorption (ADS) to simultaneously and effectively remove Cd2+ and Pb2+ species from aqueous solution. To implement the process, bentonite particles of submicro-meter size were used to first adsorb the heavy metal ions. These particles were subsequently trapped and removed by DEP. The effects of the adsorbent dosage, DEP cell voltage and the capture pool numbers on the removal rate were investigated in batch processes, which allowed us to determine the optimal experimental conditions. The high removal efficiency, 97.3% and 99.9% for Cd2+ and Pb2+, respectively, were achieved when the ions are coexisting in the system. The microstructure of bentonite particles before and after ADS/DEP was examined by scanning electron microscopy. Our results suggest that the dielectrophoresis-assisted adsorption method has a high capability to remove the heavy metals from wastewater.

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Effect of chemical dose on phosphorus removal and membrane fouling control in a UCT-MBR
Guangrong Sun, Chuanyi Zhang, Wei Li, Limei Yuan, Shilong He, Liping Wang
Front. Environ. Sci. Eng.    2019, 13 (1): 1-.
Abstract   HTML   PDF (1281KB)

Phosphorus removal was enhanced effectively by dosing aluminum sulfate and effluent phosphorus concentration was lower than 0.5 mg/L.

Sludge activity was not inhibited but improved slightly with addition of aluminum sulfate.

EPS concentrations both in mixed liquid and on membrane surface were decreased, contributing to the effective mitigation of membrane fouling.

To enhance phosphorus removal and make the effluent meet the strict discharge level of total phosphorus (TP, 0.5 mg/L), flocculant dosing is frequently applied. In this study, the performance of aluminum sulfate dosing in a University of Cape Town Membrane Bioreactor (UCT-MBR) was investigated, in terms of the nutrients removal performance, sludge characteristics and membrane fouling. The results indicated that the addition of aluminum sulfate into the aerobic reactor continuously had significantly enhanced phosphorus removal. Moreover, COD, NH4+-N and TN removal were not affected and effluent all met the first level A criteria of GB18918-2002. In addition, the addition of aluminum sulfate had improved the sludge activity slightly and reduced trans-membrane pressure (TMP) increase rate from 1.13 KPa/d to 0.57 KPa/d effectively. The membrane fouling was alleviated attributed to the increased average particle sizes and the decreased accumulation of the small sludge particles on membrane surface. Furthermore, the decline of extracellular polymeric substance (EPS) concentration in mixed sludge liquid decreased its accumulation on membrane surface, resulting in the mitigation of membrane fouling directly.

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Potential sources of unintentionally produced PCB, HCB, and PeCBz in China: A preliminary overview
Xiaotu Liu, Heidelore Fiedler, Wenwen Gong, Bin Wang, Gang Yu
Front. Environ. Sci. Eng.    2018, 12 (6): 1-.
Abstract   HTML   PDF (361KB)

A preliminary analysis of potential sources for unintentionally produced PCB, HCB and PeCBz in China.

Activity rates of sources for reference years from 2000 to 2015 provided.

Emissions from a number of sources summarized and compared.

Implications for future research and regulation discussed.

Under the Stockholm Convention on Persistent Organic Pollutants (POPs), China is required not only to reduce polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/PCDF) but also unintentionally produced polychlorinated biphenyls (PCB), hexachlorobenzene (HCB) and pentachlorobenzene (PeCBz). A baseline of the sources in China that generate these unintentional POPs is needed for both research and regulation purposes. In this paper, we have compiled production data of potential sources in China and assessed them in five-year intervals from 2000 to 2015. Most of these activities experienced changes from rapid growth to slow growth. Measured data for PCB, HCB and PeCBz in samples collected from potential sources in China were reviewed. Most information was associated to thermal processes with high potential of emission, including waste incineration and ferrous and non-ferrous metal production. In addition, high levels of PCB, HCB and PeCBz were found as impurities in a few chlorinated products or as by-products in solvent production, which suggested organochlorine industry might be important sources. Finally, based on the studies reviewed, recommendations for future actions in research and policy as well as a few regulatory issues in China are discussed.

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Cited: Crossref(9) WebOfScience(5)
Detection of oxidative stress and DNA damage in freshwater snail Lymnea leuteola exposed to profenofos
Daoud Ali, Huma Ali, Saud Alifiri, Saad Alkahtani, Abdullah A Alkahtane, Shaik Althaf Huasain
Front. Environ. Sci. Eng.    2018, 12 (5): 1-.
Abstract   HTML   PDF (802KB)

Freshwater snail (Lymnea luteola L.) is good bio indicator of water pollution.

Profenofos is tested for its molluscicidal activity against Lymnea luteola L. snail.

Deleterious effects on some oxidative stress were detected.

Profenofos has a genotoxic effect on Lymnea luteola L. snails.

Extensive production and use of organophosphate pesticide in agriculture, has risen concerned about its ecotoxicity and risk assessment of insecticides, which are more important. Therefore, the present investigation was aimed to study the induction of oxidative stress and DNA damage by organophosphate insecticide profenofos (PFF) in freshwater snail Lymnea luteola (L. luteola). The median lethal value (96 h LC50) of PFF was estimated as 1.26 mg/L for L. luteola in a semi-static system and on the basis of LC50 value three concentrations viz., 0.126 (1/10 of LC50, Sublethal I), 0.63 (1/2 of LC50, Sublethal II) and 0.84 mg/L (2/3 of LC50, Sublethal III) were determined. Snails were exposed to above-mentioned concentrations of PFF along with solvent control (acetone) and negative control for 96 h. The haemolymph was collected at 24 and 96 h of after treatment. In heamolymph of PFF exposed snail, lipid peroxide, glutathione reduced glutathione S transferase and superoxide dismutase activities at the tested concentrations significantly differ from those in the control. The genotoxicity induced in hemocytes of treated snails was measured by alkaline single cell gel electrophoresis assay. The data of this experiment demonstrated significantly enhancement of oxidative stress and DNA damage in the treated snails as compared to controls. Also, we observed statistically significant correlations of ROS with DNA damage (% tail DNA) (R2 = 0.9708) for 24 h and DNA damage (R2 = 0.9665) for 96 h.

Results of the current experiment can be useful in risk assessment of PFF among aquatic organisms. The study confirmed the use of comet assay for in vivo laboratory experiments using freshwater snail for selecting the toxic potential of industrial chemicals and environmental contaminants.



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Sonication and grinding pre-treatments on Gelidium amansii seaweed for the extraction and characterization of Agarose
Kit Wayne Chew, Pau Loke Show, Yee Jiun Yap, Joon Ching Juan, Siew Moi Phang, Tau Chuan Ling, Jo-Shu Chang
Front. Environ. Sci. Eng.    2018, 12 (4): 2-.
Abstract   HTML   PDF (281KB)

Effects of sonication and grinding pretreatment on agarose quality were observed.

Successful agarose extraction with direct PEG method without the need to dry agar.

FTIR spectra and the characteristics peaks in agarose are explained.

Improvements in gel strength and sulfate content properties in agarose samples.

Various pretreatments methods including sonication and grinding were performed on red seaweed Gelidium amansii for the subsequent extraction of agarose. The agarose products are usually extracted from agar powder products from seaweeds. In this study, the agarose was extracted using a direct polyethylene glycol (PEG) method without the need to first process the agar from seaweed. The agar extract was frozen then thawed and mixed directly with PEG solution to precipitate the agarose. The quality of agarose obtained was evaluated through physico-chemical properties analysis which includes spectral technique (FTIR), melting and boiling point, gel strength and sulfate content. These properties were compared with a non-pretreated sample and it was found that the addition of pretreatment steps improved the quality of agarose but gave a slightly lower yield. The gel strength of pretreated samples was much higher and the sulfate content was lower compared to non-pretreated samples. The best pretreatment method was sonication which gave gel strength of 742 g cm2 and sulfate content of 0.63%. The extraction of agarose can be further improved with the use of different neutralizing agents. Pretreating the seaweed shows potential in improving the quality of agarose from seaweed and can be applied for future extraction of the agarose.

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Cited: Crossref(3) WebOfScience(2)
Energy reduction of a submerged membrane bioreactor using a polytetrafluoroethylene (PTFE) hollow-fiber membrane
Taro Miyoshi, Thanh Phong Nguyen, Terumi Tsumuraya, Hiromu Tanaka, Toru Morita, Hiroki Itokawa, Toshikazu Hashimoto
Front. Environ. Sci. Eng.    2018, 12 (3): 1-.
Abstract   HTML   PDF (958KB)

The fiber length and packing density of the PTFE membrane element were increased.

The MBR was stably operated under an SADm of 0.13 m3·m-2·hr-1.

Specific energy consumption was estimated to be less than 0.4 kWh·m-3.

In this study, we modified a polytetrafluoroethylene (PTFE) hollow-fiber membrane element used for submerged membrane bioreactors (MBRs) to reduce the energy consumption during MBR processes. The high mechanical strength of the PTFE membrane made it possible to increase the effective length of the membrane fiber from 2 to 3 m. In addition, the packing density was increased by 20% by optimizing the membrane element configuration. These modifications improve the efficiency of membrane cleaning associated with aeration. The target of specific energy consumption was less than 0.4 kWh·m-3 in this study. The continuous operation of a pilot MBR treating real municipal wastewater revealed that the MBR utilizing the modified membrane element can be stably operated under a specific air demand per membrane surface area (SADm) of 0.13 m3·m-2·hr-1 when the daily-averaged membrane fluxes for the constant flow rate and flow rate fluctuating modes of operation were set to 0.6 and 0.5 m3·m-2·d-1, respectively. The specific energy consumption under these operating conditions was estimated to be less than 0.37 kWh·m-3. These results strongly suggest that operating an MBR equipped with the modified membrane element with a specific energy consumption of less than 0.4 kWh·m-3 is highly possible.

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End-of-life batteries management and material flow analysis in South Korea
Hyunhee Kim, Yong-Chul Jang, Yeonjung Hwang, Youngjae Ko, Hyunmyeong Yun
Front. Environ. Sci. Eng.    2018, 12 (3): 3-.
Abstract   HTML   PDF (660KB)

Analysis of collection and recycling system of end-of-life batteries was examined.

Relatively limited fractions of portable batteries were collected by EPR system.

More effective and diverse collection pathways should be developed.

Consumers increasingly have worn-out batteries as electrical and electronic equipment with new technical developments are introduced into the market and quickly replace older models. As a result, large amounts of end-of-life (EOL) or waste batteries are generated. Such batteries may contain a variety of materials that includes valuable resources as well as toxic elements. Thus, the proper recycling and management of batteries is very important from the perspective of resource conservation and environmental effect. The collection and recycling of EOL batteries is relatively low in South Korea compared to other countries, although an extended producer responsibility (EPR) policy was adopted for battery recycling in 2003. In this study, the management and material flow of EOL batteries is presented to determine potential problems and quantitative flow, based on literature review, site visits to battery recycling facilities, and interviews with experts in the Korea Battery Recycling Association (KBRA), manufacturers, and regulators in government. The results show that approximately 558 tons of manganese-alkaline batteries, the largest fraction among recycling target items, was disposed in landfills or incinerators in 2015, while approximately 2,000 tons of batteries were recovered at a recycling facility by simple sorting and crushing processes. By raising environmental awareness, more diverse and effective collection systems could be established for consumers to easily dispose of EOL batteries in many places. Producers, retailers and distributors in South Korea should also play an important role in the collection of EOL batteries from consumers. Lithium-ion batteries from many electronic devices must be included in the EPR system for resource recovery.

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