Viable But Nonculturable (VBNC) Bacteria, which represent a unique population of microorganisms in drinking water systems, have become a potential threat to human health. Current studies on VBNC cells usually fail to obtain pure VBNC state bacteria, which may lead to inaccurate results. We therefore introduce a novel method of VBNC cell separation and purification in this paper. PAH-coated magnetic nanoparticles (MNPs) were synthesized and found to be capable of capturing and releasing bacterial cells with high efficiency. With the aid of an additional incubation step, VBNC cells were easily isolated and purified from normal bacteria using functional MNPs. Our method represents a new technique that can be utilized in studies of VBNCs.
Nitrogen (N) and phosphorus (P) released from the sediment to the surface water is a major source of water quality impairment. Therefore, inhibiting sediment nutrient release seems necessary. In this study, red soil (RS) was employed to control the nutrients released from a black-odorous river sediment under flow conditions. The N and P that were released were effectively controlled by RS capping. Continuous-flow incubations showed that the reduction efficiencies of total N (TN), ammonium (NH4+-N), total P (TP) and soluble reactive P (SRP) of the overlying water by RS capping were 77%, 63%, 77% and 92%, respectively, and nitrification and denitrification occurred concurrently in the RS system. An increase in the water velocity coincided with a decrease in the nutrient release rate as a result of intensive water aeration.
Microwave irradiation has been used to prepare Al, Fe-pillared clays from a natural Tunisian smectite from the El Hicha deposit (province of Gabes). Chemical analysis, XRD spectra and surface properties evidenced the success of pillaring process. The obtained solids present higher surface area and pore volume than conventionally prepared Al-Fe pillared clays. The main advantages of the microwave methodology are the considerable reduction of the synthesis time and the consumption of water. The microwave-derived Al-Fe pillared clays have been tested for catalytic wet air oxidation (CWAO) of phenol in a stirred tank at 160°C and 20 bar of pure oxygen pressure. These materials are efficient for CWAO of phenol and are highly stable despite the severe operating conditions (acidic media, high pressure, high temperature). The catalyst deactivation was also significantly hindered when compared to conventionally prepared clays. Al-Fe pillared clays prepared by microwave methodology are promising as catalysts for CWAO industrial water treatment.
Treating water contaminants via heterogeneously catalyzed reduction reaction is a subject of growing interest due to its good activity and superior selectivity compared to conventional technology, yielding products that are non-toxic or substantially less toxic. This article reviews the application of catalytic reduction as a progressive approach to treat different types of contaminants in water, which covers hydrodehalogenation for wastewater treatment and hydrogenation of nitrate/nitrite for groundwater remediation. For hydrodehalogenation, an overview of the existing treatment technologies is provided with an assessment of the advantages of catalytic reduction over the conventional methodologies. Catalyst design for feasible catalytic reactions is considered with a critical analysis of the pertinent literature. For hydrogenation, hydrogenation of nitrate/nitrite contaminants in water is mainly focused. Several important nitrate reduction catalysts are discussed relating to their preparation method and catalytic performance. In addition, novel approach of catalytic reduction using in situ synthesized H2 evolved from water splitting reaction is illustrated. Finally, the challenges and perspective for the extensive application of catalytic reduction technology in water treatment are discussed. This review provides key information to our community to apply catalytic reduction approach for water treatment.
In recent years, many industrial enterprises located in the urban centers of China have been relocated owing to the rapid increase in urban development. At the sites abandoned by these enterprises, volatile organic compounds have frequently been detected, sometimes at high concentrations, particularly at sites abandoned by chemical manufacturing enterprises. With the redevelopment of sites and changes in land-use type associated with these sites, substantial amounts of contaminated soils now require remediation. Since China is a developing country, soil remediation warrants the usage of techniques that are suitable for addressing the unique challenges faced in this country. Land shortage is a common problem in China; the large numbers of contaminated sites, tight development schedules, and limited financial resources necessitate the development of cost-effective methods for land reclamation. Mechanical soil aeration is a simple, effective, and low-cost soil remediation technique that is particularly suitable for the remediation of large volatile organic compound-contaminated sites. Its effectiveness has been confirmed by conducting laboratory studies, pilot tests, and full-scale projects. This study reviews current engineering practice and developmental trends of mechanical soil aeration and analyzes the advantages and disadvantages of this technology for application in China as an emerging soil remediation market. The findings of this study might aid technology development in China, as well as assist other developing countries in the assessment and implementation of costeffective hazardous waste site soil remediation programs.
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.
Pharmaceutically active compounds in wastewater released from human consumption have received considerable attention because of their possible risks for aquatic environments. In this study, the occurrence and removal of 10 pharmaceuticals in three municipal wastewater treatment plants in southern China were investigated and the environmental risks they posed were assessed. Nifedipine, atenolol, metoprolol, valsartan and pravastatin were detected in the influent wastewater. The highest average concentration in the influents was observed for metoprolol (164.6 ng/L), followed by valsartan (120.3 ng/L) in August, while median concentrations were higher in November than in August. The total average daily mass loadings of the pharmaceuticals in the three plants were 289.52 mg/d/person, 430.46 mg/d/person and 368.67 mg/d/person, respectively. Elimination in the treatment plants studied was incomplete, with metoprolol levels increasing during biological treatment. Biological treatment was the most effective step for PhACs removal in all of the plants studied. Moreover, the removal of PhACs was observed with higher efficiencies in August than in November. The WWTP equipped with an Unitank process exhibited similar removals of most PhACs as other WWTPs equipped with an anoxic/oxic (A/O) process or various anaerobic-anoxic-oxic (A2/O) process. The environmental risk assessment concluded that all of the single PhAC in the effluents displayed a low risk (RQ<0.1) to the aquatic environments.
The feasibility of using Phragmites australis-JS45 system in removing nitrobenzene from sediments was conducted. However, it was observed that nitrobenzene degraded rapidly and was removed completely within 20 days in native sediments, raising the possibility that indigenous microorganisms may play important roles in nitrobenzene degradation. Consequently, this study aimed to verify this possibility and investigate the potential nitrobenzene degraders among indigenous microorganisms in sediments. The abundance of inoculated strain JS45 and indigenous bacteria in sediments was quantified using real-time polymerase chain reaction. Furthermore, community structure of the indigenous bacteria was analyzed through high throughput sequencing based on Illumina MiSeq platform. The results showed that indigenous bacteria in native sediments were abundant, approximately 1014 CFU/g dry weight, which is about six orders of magnitude higher than that in fertile soils. In addition, the levels of indigenous Proteobacteria (Acinetobacter, Comamonadaceae_ uncultured, Pseudomonas, and Thauera) and Firmicutes (Clostridium, Sporacetigenium, Fusibacter, Youngiibacter, and Trichococcus) increased significantly during nitrobenzene removal. Their quantities sharply decreased after nitrobenzene was removed completely, except for Pseudomonas and Thauera. Based on the results, it can be concluded that indigenous microorganisms including Proteobacteria and Firmicutes can have great potential for removing nitrobenzene from sediments. Although P. australis - JS45 system was set up in an attempt to eliminate nitrobenzene from sediments, and the system did not meet the expectation. The findings still provide valuable information on enhancing nitrobenzene removal by optimizing the sediment conditions for better growth of indigenous Proteobacteria and Firmicutes.
The Environmental Burden of Disease (EBD) approach for outdoor air pollution has been used to calculate premature deaths and average potential years of life lost attributable to air pollution in China over the past 10 years with differences between the North and the South of the country being analyzed. The results indicate that: (1) Between 2004 and 2013, annual premature deaths attributable to outdoor air pollution in China ranged from 350000 to 520000. In 2013, deaths resulting from air pollution in China represented 9.9% of the country’s total deaths. (2) In 2004, the average life expectancy of the Chinese population and the number of potential years of life lost (PYLL) attributable to air pollution was 69.6 and 1.85 years respectively as compared to 74.4 and 0.67 years respectively in 2013. (3) The number of the PYLL attributable to air pollution in the northern regions of China is found to be larger than that of the southern regions. The PYLL figures of the northern and southern regions in 2004 were 2.3 and 1.8 years, respectively, with a difference of 0.5 years, as compared to 1.4 and 0.7 years respectively with a difference of 0.7 years in 2013.
Since the concept of the osmotic microbial fuel cell (OsMFC) was introduced in 2011, it has attracted growing interests for its potential applications in wastewater treatment and energy recovery. However, forward osmosis (FO) membrane fouling resulting in a severe water flux decline remains a main obstacle. Until now, the fouling mechanisms of FO membrane especially the development of biofouling layer in the OsMFC are not yet clear. Here, the fouling behavior of FO membrane in OsMFCs was systematically investigated. The results indicated that a thick fouling layer including biofouling and inorganic fouling was existed on the FO membrane surface. Compared to the inorganic fouling, the biofouling played a more important role in the development of the fouling layer. Further analyses by the confocal laser scanning microscopy (CLSM) implied that the growth of biofouling layer on the FO membrane surface in the OsMFC could be divided into three stages. Initially, microorganisms associated with ß-D-glucopyranose polysaccharides were deposited on the FO membrane surface. After that, the microorganisms grew into a biofilm caused a quick decrease of water flux. Subsequently, some of microorganisms were dead due to lack of nutrient source, in the meantime, polysaccharide and proteins in the biofouling layer were decomposed as nutrient source, thus leading to a slow development of the biofouling layer. Moreover, the microorganisms played a significant role in the formation and development of the biofouling layer, and further studies are needed to mitigate the deposition of microorganisms on FO membrane surfaces in OsMFCs.
Direct individual analysis using Scanning Electron Microscopy combined with online observation was conducted to examine the S-rich particles in PM2.5 of two typical polluted haze episodes in summer and winter from 2014 to 2015 in Beijing. Four major types of S-rich particles, including secondary CaSO4 particles (mainly observed in summer), S-rich mineral particles (SRM), S-rich water droplets (SRW) and (C, O, S)-rich particles (COS) were identified.We found the different typical morphologies and element distributions of S-rich particles and considered that (C, O, S)-rich particles had two major mixing states in different seasons. On the basis of the S-rich particles’ relative abundances, S concentrations and their relationships with PM2.5 as well as the seasonal comparison, we revealed that the S-participated formation degrees of SRM and SRW would enhance with increasing PM2.5 concentration. Moreover, C-rich matter and sulfate had seasonally different but significant impacts on the formation of COS.
Low-impact development (LID) technologies, such as bioretention areas, rooftop rainwater harvesting, and xeriscaping can control stormwater runoff, supply non-potable water, and landscape open space. This study examines a hybrid system (HS) that combines LID technologies with a centralized water system to lessen the burden on a conventional system (CS). CS is defined as the stormwater collection and water supply infrastructure, and the conventional landscaping choices in the City of Atlanta. The study scope is limited to five single-family residential zones (SFZs), classified R-1 through R-5, and four multi-family residential zones (MFZs), classified RG-2 through RG-5. Population density increases from 0.4 (R-1) to 62.2 (RG-5) persons per 1,000 m2. We performed a life cycle assessment (LCA) comparison of CS and HS using TRACI 2.1 to simulate impacts on the ecosystem, human health, and natural resources.We quantified the impact of freshwater consumption using the freshwater ecosystem impact (FEI) indicator. Test results indicate that HS has a higher LCA single score than CS in zones with a low population density; however, the difference becomes negligible as population density increases. Incorporating LID in SFZs and MFZs can reduce potable water use by an average of 50% and 25%, respectively; however, water savings are negligible in zones with high population density (i.e., RG-5) due to the diminished surface area per capita available for LID technologies. The results demonstrate that LID technologies effectively reduce outdoor water demand and therefore would be a good choice to decrease the water consumption impact in the City of Atlanta.
Wet air oxidation (WAO) and catalytic wet air oxidation (CWAO) are efficient processes to degrade organic pollutants in water. In this paper, we especially reviewed the WAO and CWAO processes for phenolic compounds degradation. It provides a comprehensive introduction to the CWAO processes that could be beneficial to the scientists entering this field of research. The influence of different reaction parameters, such as temperature, oxygen pressure, pH, stirring speed are analyzed in detail; Homogenous catalysts and heterogeneous catalysts including carbon materials, transitional metal oxides and noble metals are extensively discussed, among which Cu based catalysts and Ru catalysts were shown to be the most active. Three different kinds of the reactor implemented for the CWAO (autoclave, packed bed and membrane reactors) are illustrated and compared. To enhance the degradation efficiency and reduce the cost of the CWAO process, biological degradation can be combined to develop an integrated technology.
In this research, supercritical carbon dioxide extraction (SFE) showed better extraction effect when compared with Solid- liquid extraction (SLE), Soxhlet extraction (SE) and Ultrasonic extraction (UE), not only in the rate but also the time. The comparison among these three extraction modifiers, including acetone, ethanol and methanol demonstrated that ethanol was preferred to SFE due to its high extraction effect and low toxicology. In addition, parameter of SFE, influence of temperature and pressure were investigated, and the best extraction effect was achieved at the optima conditions, temperature of 40°C and the pressure of 35 MPa. Thus, SFE is a highly effective method for flavonols extraction, requiring minimum energy and producing non-toxic byproduct. SFE-GC system is applied for the evaluation on flavonols that plays a key role in plant resistance to heavy metal, with its content and synthetase gene expression significantly increasing in plant when threatened by heavy metal. Besides, results indicated that flavonols can improve plant resistance to oxidative stress by quenching the redundant ROS in matrix.
Flow cytometry (FCM) has been widely used in multi-parametric assessment of cells in various research fields, especially in environmental sciences. This study detected the metabolic activity of Escherichia coli and Staphylococcus aureus by using an FCM method based on 5-cyano-2,3-ditolyltetrazolium chloride (CTC); the accuracy of this method was enhanced by adding SYTO 9 and 10%R2A broth. The disinfection effects of chlorine, chloramine, and UV were subsequently evaluated by FCM methods. Chlorine demonstrated stronger and faster destructive effects on cytomembrane than chloramine, and nucleic acids decomposed afterwards. The metabolic activity of the bacteria persisted after the cytomembranewas damaged as detected using CTC. Low-pressure (LP) UV or medium-pressure (MP) UV treatments exerted no significant effects on membrane permeability. The metabolic activity of the bacteria decreased with increasing UV dosage, and MP-UV was a stronger inhibitor of metabolic activity than LP-UV. Furthermore, the membrane of Gram-positive S. aureus was more resistant to chlorine/chloramine than that of Gram-negative E. coli. In addition, S. aureus showed higher resistance to UV irradiation than E. coli.
Methane fermentation process can be restricted and even destroyed by the accumulation of propionate because it is the most difficult to be anaerobically oxidized among the volatile fatty acids produced by acetogenesis. To enhance anaerobic wastewater treatment process for methane production and COD removal, a syntrophic propionate-oxidizing microflora B83 was obtained from an anaerobic activated sludge by enrichment with propionate. The inoculation of microflora B83, with a 1:9 ratio of bacteria number to that of the activated sludge, could enhance the methane production from glucose by 2.5 times. With the same inoculation dosage of the microflora B83, COD removal in organic wastewater treatment process was improved from 75.6% to 86.6%, while the specific methane production by COD removal was increased by 2.7 times. Hydrogen-producing acetogenesis appeared to be a rate-limiting step in methane fermentation, and the enhancement of hydrogen-producing acetogens in the anaerobic wastewater treatment process had improved not only the hydrogen-producing acetogenesis but also the acidogenesis and methanogenesis.
Ibuprofen (IBU) is widely used in the world as anti-inflammatory drug, which posed health risk to the environment. A bacterium capable of degrading IBU was isolated from activated sludge in a sewage treatment plant. According to its morphological, physiologic, and biochemical characteristics, as well as 16S rRNA sequence analysis, the strain was identified as Serratia marcescens BL1 (BL1). Degradation of IBU required the presence of primary substrate. After a five-day cultivation with yeast powder at 30°C and pH 7, the highest degradation (93.47%±2.37%) was achieved. The process of BL1 degrading IBU followed first-order reaction kinetics. The BL1 strain was applied to a small biological aerated filter (BAF) device to form a biofilm with activated sludge. IBU removal by the BAF was consistent with the results of static tests. The removal of IBU was 32.01% to 44.04% higher than for a BAF without BL1. The indigenous bacterial community was able to effectively remove CODMn (permanganate index) and ammonia nitrogen in the presence of BL1.
To reveal the distribution characteristics of phytoplankton and the main influence factors under different conditions in the urban rivers, the investigations were conducted during autumn and winter 2014 in Changzhou City, East China. 178 taxa of phytoplankton belonging to 28 functional assemblages were identified. In autumn, the phytoplankton community compositions have high similarity for enhanced hydrological connectivity. The chlorophytes and diatoms (prevailing functional groups C, F, J, P), together with euglenoids (W1), showed high proportions of biomass in the main rivers and connected rivers. It was related to the well mixed eutrophic conditions. The phytoplankton community exhibited spatiotemporal heterogeneity in winter. Affected by the low water level and temperature, the free-living phytoflagellates (X2) replaced groups F and J in the main rivers. Phytoplankton productivity was the highest in the Tongji River. Chlorophytes Dictyosphaerium ehrenbergianum and Chlamydobotrys stellata had an overwhelming superiority during the winter bloom. They were significantly correlated with ammonium, total phosphorus and biochemical oxygen demand. Affected by tail water supply, the diatoms (MP) and euglenoids (W1) dominated in a beheaded river. The multivariate analyses based on the phytoplankton functional groups helped to evaluate the relationships and variations between the urban rivers. The redundancy analysis (RDA) results showed that nitrate nitrogen, water temperature, total nitrogen and total suspended solids were the main influence factors on the phytoplankton community. Except MP, the prevailing groups all showed significant negative correlations with nitrate nitrogen. Availability and utilization of dissolved inorganic nitrogen and hydrodynamic conditions affected the phytoplankton distribution.
Time series of nanoparticle number concentration during new particle formation (NPF) events in the urban environment of Brisbane, Australia, showed that the formation of charged particles often occurred before that of neutral particles. We monitored 241 days during the calendar year 2012 over which NPF events were observed on 108 days. We studied the times at which the charged and neutral particle concentrations in the size range 1.8–3.2 nm reached their peak values and found that they were clearly different in 50 events with the peak neutral particle concentration lagging behind the charged particle concentration during 42 of these events with a mean time lag of 24±12 min. While the charged particles were more likely to form before the neutral particles, once formed, the growth rate of the particles did not depend on their charge. While ion-induced nucleation is not the dominant mechanism of NPF in the atmosphere, our observations suggest that the presence of ions in the atmosphere plays a role that cannot be ignored.
Sulfamethoxazole (SMX) and trimethoprim (TMP) are two critical sulfonamide antibiotics with enhanced persistency that are commonly found in wastewater treatment plants. Recently, more scholars have showed interests in how SMX and TMP antibiotics are biodegraded, which is seldom reported previously. Novel artificial composite soil treatment systems were designed to allow biodegradation to effectively remove adsorbed SMX and TMP from the surface of clay ceramsites. A synergy between sorption and biodegradation improves the removal of SMX and TMP. One highly efficient SMX and TMP degrading bacteria strain, Bacillus subtilis, was isolated from column reactors. In the removal process, this bacteria degrade SMX and TMP to NH4+, and then further convert NH4+ to NO3– in a continuous process. Microbial adaptation time was longer for SMX degradation than for TMP, and SMX was also able to be degraded in aerobic conditions. Importantly, the artificial composite soil treatment system is suitable for application in practical engineering.
