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This paper briefly analyzes COVID-19 cases during Wuhan lockdown and travel restrictions on 23 January 2020 to 23 June 2020, which included total confirmed, in critical condition, deaths, recovered, and suspected cases in China. Results showed that there were 28,942 suspected cases on February 8, 2020, at the peak; then, it almost declined continually to only several cases. Total confirmed cases were more than 80,000 on March 1, 2020, but less than 84,000, and deaths were more than 3000 on March 4, 2020, but less than 4640, totally, thanks for the right public measures for COVID-19 in China, such as the Wuhan City lockdown and travel restrictions for isolation; positive screening and testing; and establishing a Huoshenshan hospital, a Leishenshan hospital, and a number of Fangcang shelter hospitals, traditional Chinese medicine and a combination of Chinese and western medicine, and the launch of the clinical trials of antiviral drugs (Lianhua Qingwen, remdesivir, and chloroquine). In addition, the iRT-ABCDEF program is very useful to control domestic, imported, and asymptomatic cases. Cases in critical condition decrease continually after the peak of 11,977 cases on February 18, 2020, and recovered cases increase continually to over 78,400 cases due to these right public measures and effective treatments. In recent months, there are only 2 deaths and only about ten cases in critical condition. All in all, these public measures in China are confirmed to be very effective and are worth conducting in countries worldwide.

The 8th International Conference on Geochemistry in the Topics & Sub-tropics (GeoTrop 2017): Ecotoxicology of persistent toxic substances in food production was held during 9–12 December 2017 at the Peking University Shenzhen Graduate School in Shenzhen, China. The conference was organized due to the urgent needs to investigate the persistent evidence, environmental behavior and ecotoxicological effects of toxic substances of the food production systems which became a certain issue due to the rapid development of agricultural/aquacultural industries and growing concerns for public food safety. In Southeast Asia and especially South China (including Hong Kong), frequent occurrence of persistent toxic substances (PTSs) and their implication to health risks in humans have been reported in river/marine water and sediments (e.g. freshwater fish ponds and marine fish cages), farm soils (e.g. paddy soils), and garden soils (e.g. horticulture) and adjacent ecosystems (Lam et al. 2016; Liang et al. 2011; Tao et al. 2016; Xiong et al. 2016). The contamination levels of PTSs in these environmental media are crucial to the quality of fishery, aquatic and agricultural products, posing direct influences on food security. Therefore, there has been a special emphasis on environmental and health impacts of PTSs on food production systems in this region. The GeoTrop 2017 was co-organized by Peking -University Shenzhen Graduate School (China), Shenzhen Center for Disease Control and Prevention (China), Zhejiang A&F University (China), Jinan University (China), The Education University of Hong Kong, Hong Kong Polytechnic University, Hong Kong Baptist University and Korea University. The 1st Conference of this series was held in Kingston, Jamaica, 1994. The 2nd and the 3rd Conferences were held in Kula Lumpur, Malaysia and in Hong Kong, 1997 and 1999, with the 4th Conference in Townsville, Australia, 2001. The 5th and 6th Conferences were hosted by the Chinese Academy of Sciences in Haikou and Xiamen (China), 2004 and 2010, respectively. The 7th Conference was held in Bangkok, Thailand, 2012. Herein, the GeoTrop 2017 was co-chaired by Professor Huchun Tao from Peking University Shenzhen Graduate School, Professor Yong Sik Ok from Korea University, Professor Cehui Mo from Jinan University, and Professor Shengchun Wu from Zhejiang A&F University. The honorary chairman Professor Ming-Hung Wong was from The Education University of Hong Kong.

Mealworms from three different regions: Guangzhou, Tai'an and Shenzhen, were fed with three commonly used microplastics of polystyrene (PS), polyvinyl chloride (PVC) and low-density polyethylene (LDPE) for 1 month under favorable conditions, respectively. The survival rate and average weight of mealworms, the mass loss of microplastics and the production of frass were recorded every 4 days. Samples collected were characterized by X-ray diffraction, fourier transform infrared spectroscopy, thermogravimetric analyzer and gel permeation chromatography. The results showed that mealworms from Tai'an and Shenzhen could effectively metabolize the whole microplastics tested, while those from Guangzhou could only metabolize PS and LDPE. Besides, LDPE could be degraded by mealworms from Tai'an and Shenzhen, while those from Guangzhou showed no such capability, indicating that mealworms from different regions present different metabolism effects. Furthermore, PS and LDPE are more likely to be metabolized compared with PVC.

A bioelectrochemical sensor (BES) was constructed for toxicity assessment of copper in contaminated domestic sewage. Electrochemically active bacteria (EAB), whose growth was supported by the bioenergy generated from an in situ metallurgical process, functioned as the sensing elements. The external resistance of metallurgical BES was optimized based on linear sweep voltammetry analysis. The stabilized BES was utilized to monitor the copper toxicity in real wastewater. During the less than 1-h sensing period, copper concentration ranging from 1 to 5 mg L−1 could be detected. A power output of around 100 Wh (kg Cu)−1 and metallic copper resource were obtained simultaneously. This study demonstrated that the highly active EAB species enriched in metallurgical BES could be a promising candidate for rapid and reliable evaluation of copper toxicity in real domestic wastewater.

Omega-3 fatty acids have proven to be very essential for human health due to their multiple health benefits. These essential fatty acids (EFAs) need to be uptaken through diet because they are unable to be produced by the human body. These are important for skin and hair growth as well as for proper visual, neural, and reproductive functions of the body. These fatty acids are proven to be extremely vital for normal tissue development during pregnancy and infancy. Omega-3 fatty acids can be obtained mainly from two dietary sources: marine and plant oils. Eicosapentaenoic acid (EPA; C20:5 n-3) and docosahexaenoic acid (DHA; C22:6 n-3) are the primary marine-derived omega-3 fatty acids. Marine fishes are high in omega-3 fatty acids, yet high consumption of those fishes will cause a shortage of fish stocks existing naturally in the oceans. An alternative source to achieve the recommended daily intake of EFAs is the demand of today. In this review article, an attempt has, therefore, been made to discuss the importance of omega-3 fatty acids and the recent developments in order to produce these fatty acids by the genetic modifications of the plants.

This study evaluated uranium sequestration performance in iron-rich (30 g/kg) sediment via bioreduction followed by reoxidation. Field tests (1383 days) at Oak Ridge, Tennessee demonstrated that uranium contents in sediments increased after bioreduced sediments were re-exposed to nitrate and oxygen in contaminated groundwater. Bioreduction of contaminated sediments (1200 mg/kg U) with ethanol in microcosm reduced aqueous U from 0.37 to 0.023 mg/L. Aliquots of the bioreduced sediment were reoxidized with O2, H2O2, and NaNO3, respectively, over 285 days, resulting in aqueous U of 0.024, 1.58 and 14.4 mg/L at pH 6.30, 6.63 and 7.62, respectively. The source- and the three reoxidized sediments showed different desorption and adsorption behaviors of U, but all fit a Freundlich model. The adsorption capacities increased sharply at pH 4.5 to 5.5, plateaued at pH 5.5 to 7.0, then decreased sharply as pH increased from 7.0 to 8.0. The O2-reoxidized sediment retained a lower desorption efficiency at pH over 6.0. The NO3−-reoxidized sediment exhibited higher adsorption capacity at pH 5.5 to 6.0. The pH-dependent adsorption onto Fe(III) oxides and formation of U coated particles and precipitates resulted in U sequestration, and bioreduction followed by reoxidation can enhance the U sequestration in sediment.

Academics researchers and “citizen scientists” from 22 countries confirmed that yellow mealworms, the larvae of Tenebrio molitor Linnaeus, can survive by eating polystyrene (PS) foam. More detailed assessments of this capability for mealworms were carried out by12 sources: five from the USA, six from China, and one from Northern Ireland. All of these mealworms digested PS foam. PS mass decreased and depolymerization was observed, with appearance of lower molecular weight residuals and functional groups indicative of oxidative transformations in extracts from the frass (insect excrement). An addition of gentamycin (30 mg g−1), a bactericidal antibiotic, inhibited depolymerization, implicating the gut microbiome in the biodegradation process. Microbial community analyses demonstrated significant taxonomic shifts for mealworms fed diets of PS plus bran and PS alone. The results indicate that mealworms from diverse locations eat and metabolize PS and support the hypothesis that this capacity is independent of the geographic origin of the mealworms, and is likely ubiquitous to members of this species.

Acyl-homoserine lactone (AHL)-based quorum sensing (QS) in the anaerobic ammonium oxidizing (anammox) consortia has attracted increasing attention. However, AHL synthase in anammox bacteria and the relationship between AHL synthetic genes and anammox activity are still not clear because anammox bacteria have not been isolated from the consortia. Two novel synthases of AHLs (JqsI-1 and JqsI-2), which are HdtS-type rather than the widely studied LuxI-type, were identified in anammox bacteria Candidatus Jettenia caeni and synthesized four AHLs. There was a correlation between AHL concentration, in situ transcriptional expression of the AHL synthase genes (jqsI-1 and jqsI-2) and genetic marker of anammox activity (hydrazine synthase gene, hzsA). And AHL add-back studies demonstrated that AHL influence the expression of hzsA to regulate anammox bacterial activity. This study provides insight into the QS communication pathway of anammox bacteria for wastewater treatment.

Sewage sludge and bagasse were used as raw materials to produce cheap and efficient adsorbent with great adsorption capacity of Pb(2+). By pyrolysis at 800 °C for 0.5 h, the largest surface area (806.57 m(2)/g) of the adsorbent was obtained, enriched with organic functional groups. The optimal conditions for production of the adsorbent and adsorption of Pb(2+) were investigated. The results of adsorb-ability fitted the Langmuir isotherm and pseudo-second-order model well. The highest Pb(2+) (at pH = 4.0) adsorption capacity was achieved by treating with 60% (v/v) HNO3. This is a promising approach for metal removal from wastewater, as well as recycling sewage sludge and bagasse to ease their disposal pressure.

Algae and mercury (Hg) are ubiquitous in marine environments. In this study, we investigated the effects of a typical marine algae of diatom Skeletonema costatum on Hg methylation by an iron-reducing bacterium of Geobacter sulfurreducens (G. sulfurreducens) PCA. In the absence of Skeletonema costatum, the bacterial MeHg production rate maximized at 104.06 ± 11.7 ng L−1 h−1 with a high Hg level, while the highest methylation efficiency was achieved at a low Hg concentration. The existence of Skeletonema costatum greatly inhibited the capability of G. sulfurreducens PCA to methylate Hg. With the increase in algal biomass, there was a significant mitigation of MeHg formation and Hg0 release, leaving a considerable proportion of immobilized Hg2+ species (up to 47%) associated with algal cell materials. These results suggest that marine algae are crucial in determining the bioavailability of Hg contaminants and the methylating potential of G. sulfurreducens PCA.

Using sodium alginate hydrogel as skeleton, in combination with chitosan and magnetic Fe3O4, a new type of magnetic chitosan/sodium alginate gel bead (MCSB) was prepared. Adsorptive removal of Cu(II) from aqueous solutions was studied by using the MCSB as a promising candidate in environmental application. Different kinetics and isotherm models were employed to investigate the adsorption process. Based on Fourier transform infrared spectroscopy, field-emission scanning electron microscope, CHNS/O elements analysis, vibration magnetometer, and various means of characterization, a comprehensive analysis of the adsorption mechanism was conducted. The MCSB had a good magnetic performance with a saturation magnetization of 12.5 emu/g. Elemental analysis proved that the addition of chitosan introduced a considerable amount of nitrogen-rich groups, contributing significantly to copper adsorption onto gel beads. The contact time necessary for adsorption was optimized at 120 min to achieve equilibrium. Experimental data showed that the adsorption process agreed well with the Langmuir isotherm model and the pseudo-second-order kinetics model. The theoretical maximum adsorption capacity of MCSB for Cu(II) could reach as high as 124.53 mg/g. In conclusion, the MCSB in this study is a novel and promising composite adsorbent, which can be applied for practical applications in due course.

At the Pearl River Estuary of southern China, mercury and its environmental problems have long been a great concern. This study investigated the distribution and speciation of mercury compounds that are significantly influenced by the increasing content of humic acid (HA, a model natural organic matter) in this region. The inorganic mercury and methyl mercury, being adsorbed and converted at different HA levels, were studied in sediments and surface water at both mariculture and their reference sites. In mariculture sediments with higher HA content (up to 4.5%), more mercury were adsorbed at different compound levels, promoting the methylation and accumulation of mercury (P 0.05) at the sediment-water interface. Seasonal shift in environmental temperature might control the HA content, subsequently favouring mercury methylation (maximum 1.75 ± 0.08 mg L

The aim of this work was to study a hybrid bioreactor landfill technology for landfill methane production from municipal solid waste. Two laboratory-scale columns were operated for about ten months to simulate an anaerobic and a hybrid landfill bioreactor, respectively. Leachate was recirculated into each column but aeration was conducted in the hybrid bioreactor during the first stage. Results showed that leachate pH in the anaerobic bioreactor maintained below 6.5, while in the hybrid bioreactor quickly increased from 5.6 to 7.0 due to the aeration. The temporary aeration resulted in lowering COD and BOD5 in the leachate. The volume of methane collected from the hybrid bioreactor was 400 times greater than that of the anaerobic bioreactor. Also, the methane production rate of the hybrid bioreactor was improved within a short period of time. After about 10 months' operation, the total methane production in the hybrid bioreactor was 212 L (16 L/kgwaste).

The occurrence and fate of free and conjugated estrogens were investigated in wastewater and sludge from five sewage treatment plants (STPs) in Guangdong Province, China. Estrone (E1) and 17β-estradiol (E2) were found in all influent samples at concentrations of 69.3-280 ng L(-1) and 1.3-30 ng L(-1), respectively. The concentrations of conjugated estrogens were from ND (not detected) to 7.6 ng L(-1). High concentrations (27.6-235 ng g(-1)) of E1 were found in sludge of some STPs indicating that sorption was an important estrogen removal mechanism. According to the mass flux analyses for estrogens in STP-A, E2 was mainly removed in the anaerobic process and E1 removal was the combined efforts of biodegradation and sorption. Abnormally high concentrations of EE2 (42.6-246 ng L(-1)), detected with gas chromatography-mass spectrometry, were found in all influent samples of the STPs, therefore interlaboratory analysis with liquid chromatography-tandem mass spectrometry was conducted for confirmation, which detected no EE2 at all. In consideration of the rather lower estimated EE2 concentration than the measured value, it was speculated that the presence of interfering substances like tetracosanic acid in the matrix could lead to overestimation of EE2 concentration. Overall, the effluents still pose potential estrogenic effect to the downstream aquatic organisms.

A Pseudomonas putida whole-cell bioreporter for detecting bioavailable copper was constructed by inserting a CueR-regulated sensor element upstream of a promoterless green fluorescent protein (GFP) reporter gene. The constructed bioreporter cells expressed GFP only in response to Cu and Ag when cultivated in different metal salt solutions. M9 supplemented medium provided higher sensitivity compared with LB medium. The optimal test condition was cell suspension with an OD600 of 0.4-0.5 incubated at 30 °C. The detection range of Cu is 1-70 mg/l under optimal test condition in M9 supplemented medium.

Heavy metal contamination has become a worldwide environmental concern due to its toxicity, non-degradability and food-chain bioaccumulation. Conventional physical and chemical treatment methods for heavy metal removal have disadvantages such as cost-intensiveness, incomplete removal, secondary pollution and the lack of metal specificity. Microbial biomass-based biosorption is one of the approaches gaining increasing attention because it is effective, cheap, and environmental friendly and can work well at low concentrations. To enhance the adsorption properties of microbial cells to heavy metal ions, the cell surface display of various metal-binding proteins/peptides have been performed using a cell surface engineering approach. The surface engineering of Gram-negative bacteria, Gram-positive bacteria and yeast towards the adsorption of heavy metals are reviewed in this article. The problems and future perspectives of this technology are discussed.

The metalloprotein, CadR, was redesigned to optimize cadmium and mercury specificity of CadR-based E. coli biosensors. By truncating 10 and 21 amino acids from the C-terminal extension of CadR, CadR-TC10 and CadR-TC21 were obtained, respectively. The genes cadR, cadR-TC10 and cadR-TC21 were used as sensing elements to construct green fluorescent protein based E.coli biosensors. Induction at 30 °C for 4 h in supplemented M9 medium was the optimized condition for the biosensor. Compared with CadR-based biosensor, there was a clear decline in induction coefficient for CadR-TC21-based biosensor (decreased by 86 % in Zn(II), 44 % in Hg(II), and only 37 % in Cd(II)). While in CadR-TC10-based biosensor, the induction coefficient decreased by 95 % in Zn(II), 70 % in Hg(II), and 67 % in Cd(II). Improved performances of CadR mutants based E. coli biosensors indicated that truncating C-terminal extension of CadR could improve the specificity.

In the present study, the Hg contamination in mariculture sites located at the estuary of Pearl River was to investigate with an attempt to analyse associated health risks of dietary exposure to both total mercury (THg) and methyl mercury (MeHg) in cultured fish and shellfish. The highest total mercury concentration (7.037 ± 0.556 ng L-1) of seawater was observed at Zhuhai Estuary. The Hg concentrations of sediment in Guishan Island were significantly higher (p

Great efforts have been made in China to retrofit and upgrade the existing municipal wastewater treatment plants (WWTPs) for enhanced removal of organic substrates and in particular nutrients. However, the removal of trace recalcitrant or hazardous organic chemicals, e.g. steroid estrogens, one group of typical endocrine disrupting chemicals, has long been overlooked. The extensive investigations on estrogen removal rates in global and Chinese WWTPs and the estrogen biodegradation kinetics results in batch laboratory experiments are reviewed in this study. The effects of estrogen initial concentration and nitrifying activated sludge are highlighted. Challenges existing in current estrogen studies are pointed out, which are relevant for researches on fate and behavior of similar down-the-drain chemicals in both Chinese and global WWTPs.

For the growing problem of mine heat hazard in the deep mining, according to the actual condition of the power source, this paper mainly analyzed the heat source of the Fourth Mine in Zhong ping Energy Chemical Group, and unprecedentedly adopted the waste heat from the gas power generation in the cooling of underground environment. The low temperature refrigerant of 5.2 °C is generat ed through a lithium bromide absorption chiller refrigeration system as the first-stage refrigerant, and the temperature of the refrigerant is further reduced to - 3.4 °C by compressed chillers as the second-stage refrigerant. Through the main shaft, the refrigerant is transported to the high- pressure side of the high-low pressure heat exchangers inside the chamber which is located in the −320 m level underground, finally, ethylene glycol solution is sent back to the ground for recycling after cold release. After the heat exchange, the 3 °C low temperature circulating water is transported to the air cooler installed in the machine. Lane of the fully mechanized coal face by the cold water pump, which cools the inlet airflow on the working face to achieve the heat hazard control. The implementation of this cooling system, which has achieved significant economic, social and environmental benefit, have showed bright prospect for extended application.

Bioenergy is renewable energy and offers the promise for reducing dependency on fossil fuels. The main environmental impacts of bioenergy are associated with land use and greenhouse gas emission. This special issue covers multidisciplinary approaches and intensive research orientations for the real challenges in bioenergy and its environmental impacts. For this special issue, we received 35 submissions from all over the world. After an initial screening, 6 submissions were declared “out of scope” and the remaining 29 were sent to reviewers. All manuscripts underwent a very rigorous peer review process. We finally selected 12 full papers and 1 review paper for this special issue. In this issue, bioenergy from algae is highly concerned, including oil production from microalgae, life cycle fossil energy ratio of algal biodiesel, microbial fuel cell (MFC) with photosynthetic algae cathode, and algal biofuel production with wastewater. MFC, a new technology for electricity generation from waste and biomass, is popular in this special issue. The authors reported that the use of nanostructured manganese oxide as cathodic catalyst and the use of carbon nanofiber modified graphite felt as anode can significantly enhance MFC performance. The review paper focused on the state-of-the-art method for assessing the greenhouse gas (GHG) emission reduction by developing energy crops and a new approach combining life cycle analysis (LCA) with biogeochemical process models to assess GHG emission reduction. Although research on bioenergy has increased in recent years, the study of developing and screening the most suitable and economically viable technology needs much further attention.

A new approach that improved the dechlorination and mineralization of 4-chlorophenol (4-CP) was demonstrated in a sequential biocathode-bioanode bioelectrochemical system (BES) with mixed photosynthetic bacteria (PSB). The biocathode with additional PSB inoculation showed higher 4-CP dechlorination efficiency (DE) and maximum current (81.8 ± 2.9%, 0.021 ± 0.002A) than that at abiotic cathode (45.3 ± 3.7%, 0.011 ± 0.002A) (P0.005). Light response in biocathode BES with or without PSB ascertained the important role of PSB played in the dechlorination and current generation. Dechlorination and mineralization of 4-CP was achieved in the sequential biocathode-bioanode BES, which could be further enhanced with PSB inoculation in both cathode chamber and anode chamber. 4-CP DE in the cathode chamber was improved from 55.0 ± 2.0% to 78.8 ± 4.9%, and the phenol degradation in the anode chamber was improved from 65.3 ± 2.1% to 71.3 ± 1.4%. This study directed a new way for improving dechlorination at biocathode and product degradation at bioanode with PSB inoculation in BES.

Pseudomonas sp. WYZ-2 was isolated from a biocathode which accelerating azo dye decolorization. When the electrode was polarized at -0.8 V (vs. SCE), WYZ-2 could exist on electrode, because the current of working electrode stabilized at -0.35 mA from -0.13 mA after inoculation. Moreover, cyclic voltammetry scanned an unidentified redox-active molecule which involved in the electron charge transfer potentially. On azo dye decolorization experiments by WYZ-2 modified electrode, electrochemical tests also indicated that the catalytic ability of WYZ-2 modified electrode was improved because charge transfer resistance decreased to 255 Ω from 720 Ω, azo dye reduction potential was shifted to -0.78 V from -0.89 V, and the maximum decolorization efficiency of azo dye was increased to 93.4% from 53.2%, comparing with unmodified electrode. Although numerous studies on azo dye decolorization employed biological agents, electrochemical activity bacteria accelerate the decolorization process using electrode as sole electron source has seldom been reported.

The feasibility of removing estrogens including 17β-estradiol (E2) and 17α-ethynyl-estradiol (EE2) was studied in a bio-electro-Fenton (BEF) system equipped with a Fe@Fe 2 O 3 /non-catalyzed carbon felt (NCF) composite cathode. E2 and EE2 were removed by reactive oxidants, produced by bio-electro-Fenton system and zero-valent iron/O 2 system, as well as adsorption. Under closed-circuit condition, 81% of E2 and 56% of EE2 were removed within 10 h in the system, in which the highest concentration of total iron ions and H 2 O 2 reached 81 and 1.2 mg/L, respectively. The maximum power density of BEF system equipped with Fe@Fe 2 O 3 /NCF electrode was 4.35 W/m 3 . Two intermediates of E1 and 6-OH-E2 were identified during Fenton oxidation of E2. This study demonstrates the degradation fate of E2 and EE2 in a BEF system equipped with Fe@Fe 2 O 3 /NCF electrodes, which provides a promising and cost-effective solution for the removal of recalcitrant contaminants with simultaneous power generation.

The cathodic reduction of complex-state copper(II) was investigated in a dual chamber microbial fuel cell (MFC). The inner resistance of MFC system could be reduced in the presence of ionizing NH 4 + , however, mass transfer was hindered at higher ammonia concentration. Thermodynamic and electrochemical analyses indicated that the processes of complex dissociation and copper reduction were governed by the ratio of T[Cu]:T[NH 3 ] and the pH of solution. The reduction of Cu ( NH 3 ) 4 2 + could be achieved via two possible pathways: (1) releasing Cu 2+ from Cu ( NH 3 ) 4 2 + , then reducing Cu 2+ to Cu or Cu 2 O and (2) Cu ( NH 3 ) 4 2 + accepting an electron and forming Cu ( NH 3 ) 2 + , and depositing as Cu or Cu 2 O consequently. At initial concentration of 350 mg T[Cu] L −1 , copper removal efficiency of 96% was obtained at pH = 9.0 within 12 h (with △Cu/△COD = 1.24), 84% was obtained at pH = 3.0 within 8 h (with △Cu/△COD = 1.72). Cu ( NH 3 ) 4 2 + was reduced as polyhedral deposits on the cathode.

A novel approach was tested for metallic silver recovery and power generation by using cathodic reduction in bioelectrochemical systems (BESs). In dual-chamber BESs (130 mL volume) with acetate as electron donor on anode, both Ag(+) ions and Ag(I) thiosulfate complex in catholyte were reduced on cathode. The reduction rate of Ag(+) was more rapid than the Ag(I) complex as expected by energetic analysis. X-ray diffraction (XRD) analysis indicated that electrodeposits on cathodes from both catholyte were metallic silver with >91% purity. The feasibility of metallic silver recovery with the BESs was confirmed using simulated photographic wastewater and up to 95% of Ag(I) removal was achieved.

A pilot-scale, membrane-free, bioelectrochemical system (BES) reactor (16 L in volume) installed by five cathodes with different distance to anode was tested for the removal of copper. CuSO4 solution was used as catholyte and anaerobic microorganisms grew as anodic biocatalyst. In the reactor, Cu(II) was reduced and recovered as solid-state copper deposits on cathodes accompanied with power production. When 600 and 2000 mg of Cu2+ were added into the cathode chamber, removal efficiency of 92% over 480 h and 48% over 672 h period with electric quantities of 2724 C and 8703 C, and cathodic efficiencies of 61.92% and 45.60% were achieved, respectively. The reduction reaction rate depended on the initial average Cu2+ concentration. The internal resistance decreased and voltage output increased as the distance of each cathode to anode decreased. The mass of metal Cu crystals and Cu(I) compounds deposited on each cathode was dependent on current intensity.

A membrane-free baffled microbial fuel cell (MFC) was developed to treat synthetic Cu(II) sulfate containing wastewater in cathode chamber and synthetic glucose-containing wastewater fed to anode chamber. Maximum power density of 314 mW/m 3 with columbic efficiency of 5.3% was obtained using initial Cu 2+ concentration of 6400 mg/L. Higher current density favored the cathodic reduction of Cu 2+ , and removal of Cu 2+ by 70% was observed within 144 h using initial concentration of 500 mg/L. Powder X-ray diffraction (XRD) analysis indicated that the Cu 2+ was reduced to Cu 2 O or Cu 2 O plus Cu which deposited on the cathode, and the deficient cathodic reducibility resulted in the formation of Cu 4 (OH) 6 SO 4 at high initial Cu 2+ concentration (500–6400 mg/L). This study suggested a novel low-cost approach to remove and recover Cu(II) from Cu 2+ -containing wastewater using MFC-type reactor.

An up-flow fixed-bed (UFB) bioreactor with patented functional polyurethane foam (FPUF) carriers was used to treat sulfide in hydrocarbon wastewater. Community compositions of autotrophic and heterotrophic bacteria were analyzed by polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE). DGGE results showed that a relatively stable bacterial community composed of heterotrophic and autotrophic bacteria formed in the bioreactor by the end of experiment, which ensured 92-100% sulfide removal efficiencies. Furthermore, autotrophic genera of Thiobacillus and Thiomonas, as well as those of the heterotrophic genus of Acinetobacter survived and exhibited high sulfide oxidation activity under all three operational conditions. Different special genera were also observed under each operational condition, such as the halophilic genus of Nesterenkonia. In addition, a new genus of sulfide oxidation bacteria was found in the bioreactor, which had the ability to synthesize cytoplasm from organic compounds. These genera have wide applications for the treatment of sulfide in hydrocarbon wastewater.

To explore the effects of total flavonoids of Hippophae rhamnoides L. (TFH), quercetin (Que) and isorhamnetin (Isor) on the intracellular free calcium ([Ca(2+)](i)) in vascular smooth muscle cells (VSMC) of spontaneously hypertensive rats (SHR) and Wistar-Kyoto rats (WKY).Fluo 3-acetoxymethylester (Fluo-3/AM) was used to observe the effects of TFH (100 mg/L) and its essential monomers, namely Que (10(-4) mol/L) and Isor (10(-4) mol/L) on changes of [Ca(2+)](i) in cultured SHR and WKY VSMC (abbr. to Ca-SHRCa-WKY) following exposure to high K(+), norepinephrine (NE) and angiotensin II (Ang II), and to compare with the effects of verapamil (Ver).(1) TFH, Que and Isor had inhibitory effects on resting Ca-SHR (P0.05), but had no significant effects on Ca-WKY (P0.05). (2) High K(+) could increase Ca-SHR more significantly than Ca-WKY (P0.05); TFH, Que and Isor could inhibit the elevation of [Ca(2+)](i) induced by high K(+)-depolarization, with the effects similar to that of Ver, and the effect on Ca-SHR was more significant than that on Ca-WKY (P0.05). (3) NE and Ang II could increase Ca-SHR more significantly than Ca-WKY (P0.05), TFH, Que and Isor had remarkably inhibitory effect on the elevation of Ca-SHR and Ca-WKY induced by NE or Ang II. (4) In the absence of extracellular Ca(2+), TFH, Que and Isor also had certain inhibitory effect on Ca-SHR and Ca-WKY induced by NE, and the effect on the former was more significant than that on the latter (P0.05).TFH, Que and Isor might decrease the levels of [Ca(2+)](i) in VSMCs by blocking both voltage-dependent calcium channels (VDC) and receptor-operated calcium channels (ROC) in physiological or pathological state, which may be one of the important mechanisms of their hypotensive and protective effects on target organs in patients with hypertension.

The photodegradation of phenol has been investigated under a high-pressure mercury lamp with a kind of jacket (glass or quartz) depending on used UV light range and a variety of experimental conditions: UV (lambda200 nm) with oxygen or with TiO2 and oxygen or with N2; UV (lambda330 nm) with oxygen or with TiO2 and oxygen or with N2. Photocatalysis and direct photolysis of phenol have different reaction pathways. Direct photolysis of phenol yielded a brown-yellow complex organic polymer in both aerobic and anaerobic environments. The polymer cannot be mineralized in an anaerobic environment. The effects of catalyst amount and oxygen concentration in the reaction atmosphere on the destruction of phenol were studied. The results prove that an appropriate catalyst amount can avoid direct photolysis and increase the mineralization rate of phenol.

The photodegradation and biodegradability have been investigated for four non-biodegradable commercial azo dyes, Reactive YellowKD-3G, Reactive Red 15, Reactive Red 24, Cationic Blue X-GRL, an indicator. Methyl Orange, and one industrial wool textile wastewater, using TiO2 suspensions irradiated with a medium pressure mercury lamp. The color removal of dyes solution and dyeing wastewater reached to above 90% within 20-30min, of photocatalytic treatment. Biochemical oxygen demand (BOD) was found to increase, while chemical oxygen demand (COD), total organic carbon (TOC) decreased, so that the ratio of BOD5/COD of the wastewater increased from original zero up to 0.75. The result implies that photocatalytic oxidation enhanced the biodegradability of the dye-containing wastewater and therefore relationship between decolorization and biodegradability exists. When the color disappeared completely, the wastewater biodegraded normally and could be discharged for further treatment. The experimental results demonstrate that it is possible to combine photocatalysis with conventional biological treatment for the remedy of wastewater containing generally non-biodegradable azo dyes. (C)1999 Elsevier Science Ltd. AII rights reserved.