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Graphical abstract Highlights • Se doping MWCNTs-graphene hybrids are prepared and used for supporting substrate. • Y-shaped DNA-aided target recycling signal amplification and hemin/G-quadruplex is used for signal amplification. • The biosensor used for PDGF-BB detection shows linear range of 0.1 pM-10 nM and detection limit of 27 fM. Abstract A highly sensitive electrochemical biosensor for detection of platelet-derived growth factor-BB (PDGF-BB) is developed by using Se-doped multi-walled carbon nanotubes (MWCNTs)-graphene hybrids as electrode supporting substrate, hemin/G-quadruplex as trace labels and Y-shaped DNA-aided target recycling as signal magnifier. The aptamer-containing hairpin probes were first immobilized on the electrode. When target PDGF-BB was added, the aptamer binded PDGF-BB to trigger catalytic assembly of two other hairpins to form many G-quadruplex Y-junction DNA structures, which released PDGF-BB to again bind the intact aptamer to initiate another assembly cycle. G-quadruplex/hemin complexes were produced when hemin was added to generate substantially amplified current output. The developed assay showed a linear range toward PDGF-BB from 0.1 pM to 10 nM with a detection limit of 27 fM (S/N = 3). The method showed excellent specificity and repeatability, and could be expediently applied for sensitive detection of other molecules by simply changing the aptamers. [ABSTRACT FROM AUTHOR]

In this work, a sandwich-type electrochemical biosensing platform is developed based on carbon sphere-MoS 2 (CS-MoS 2 ) and target recycling amplification of catalyzed hairpin assembly (CHA) strategy for ultrasensitive determination of microRNA (miRNA). The CS-MoS 2 is prepared and used as sensing substrate, which shows high specific surface area, enhanced stability and good dispersibility. The capture probe is first modified on Au nanoparticles/CS-MoS 2 modified glassy carbon electrode through Au-S band, and hairpin DNA1 (H1) then reacts with it and unfolds its loop domain by hybridizing with target miRNA-21. The opened H1 subsequently assembles with biotin labeled hairpin DNA 2 (H2) to displace the target. The liberated miRNA-21 is free and backs to the original solution to proceed next circulation, resulting in the generation of large amounts of H1–H2 duplex. Massive signal indicators horseradish peroxidase are then immobilized on electrode, and catalyze hydrogenperoxide + hydroquinone (H 2 O 2  + HQ) system to produce a strong electrochemical response. The proposed assay benefits from advantages of sandwich-type structure, favorable electrochemical properties of CS-MoS 2 and CHA target recycling amplification strategy. Therefore, it exhibits a wide linear relation between 1 × 10 −16 and 1 × 10 −10  M with a low detection limit of 1.6 × 10 −17  M for miRNA-21 detection. [ABSTRACT FROM AUTHOR]

Abstract: Higher contents of and SS in wastewater hamper the anaerobic digestion; necessitating its pretreatment to reduce them. This study reveals optimization of struvite/MAP precipitation protocol followed by anaerobic digestion of pretreated swine wastewater for pollutants removal. Levels of different treatments: stirring speeds, 400 and 160rpm; pH values, 9.0, 9.5, 10.0, 10.5, 11.0 and 11.5; and P:Mg:N ratios, 1:1:1.2, 1:1:1.7, 1:1:2.2, 1:1:2.7, 1:1:4.0 and 1:1:5.0 were evaluated for MAP crystallization. Among various combinations, protocol comprising of initial 10min stirring at 400rpm followed by 160rpm for 30min, pH 10.0, and P:Mg:N ratio 1:1:1.2 rendered the best removal efficiency for , , COD, TC and TOC. Subsequent anaerobic biodegradation revealed superiority of MAP supernatant over raw swine wastewater for methane yield and , , COD, TC and TOC removals. It suggests that struvite precipitation as pretreatment to anaerobic digestion is highly effective and advantageous in wastewater treatment. [Copyright &y& Elsevier]

Abstract: The current trend of global warming is expected to stimulate the expansion of harmful cyanobacteria blooms. Previously, the occidental type of barley straw has been used to control blooms in Europe and America, but very little is known about the antialgal abilities of its oriental relative. We tested the use of Tibetan hulless barley straw – the progenitor of oriental barley – to inhibit the growth of cyanobacterium Microcystis aeruginosa. Flow cytometry allowed assessment at single-cell level, with morphologic parameters (cell volume, cell membrane integrity) and physiological parameters (in vivo Chlorophyll a fluorescence, metabolic activity) used as endpoints. The reduction of cell densities together with integrated cell membranes suggests that Tibetan barley may act as an algistatic agent. Doses from 2.0 to 8.0gL−1 of Tibetan barley straw efficiently inhibited the alga, but these doses were much higher than those of occidental barley. Such a large dosage introduced additional nutrients, which stimulated the intracellular metabolic activity and induced two physiological subpopulations in the acute term. After mid and long-term exposure, the growth inhibition effect exceeded the stimulation effect, so that the cells’ metabolic activity and Chlorophyll a fluorescence decayed, simultaneously with shrinkage in the algal cell volume. [ABSTRACT FROM AUTHOR]

Abstract: Composting is an effective methodology for the treatment of organic waste like pig manure (PM) before land application. However, nitrogen loss through NH3 volatilization during the thermophilic phase is one of the major disadvantages of composting. The presence of Cu and Zn in compost arising from pig feed additives is also an issue. In this study the effects of bamboo charcoal (BC) and bamboo vinegar (BV) added to composting piles on nitrogen conservation and immobility of Cu and Zn during PM composting was investigated. Total Kjeldahl nitrogen (TKN) loss and mobility of Cu and Zn decreased with increased BC addition. TKN loss and mobility of Cu and Zn in the treatment with 9% BC at the end of composting significantly decreased by 65%, 35% and 39% respectively, as compared to the control. Addition of BV further decreased TKN loss. After composting, TKN loss in the treatment with 3% BC+0.4% BV was 23% lower than that in the treatment with 9% BC. The final results indicated that by adding BC or BC+BV into PM composting is an effective method to reduce TKN loss and control the mobility of Cu and Zn. [Copyright &y& Elsevier]

Objective: To investigate the struvite precipitation under constant and non-constant pH conditions and to test a stainless steel device under different operating regimes to maximize the recovery of struvite. Methods: The molar ratio of NH4 +: Mg2+: PO4 3− was adjusted to 1: 1.2: 1.2 and pH was elevated to 9.0. The absorbance measurement was used to trace the process of struvite crystallization. Wastewater and precipitate analysis was done by standard analytical methods. Results: The pH constant experiment reported a significantly higher struvite precipitation (24.6±0.86 g) than the non-constant pH experiment (19.8±1.86 g). The SAR ranged from 5.6 to 8.2 g m−2 h−1 to 3.6-4.8 g m−2 h−1 in pH constant and non-constant experiments, respectively. The highest struvite deposit on the device was found in regime 3 followed by in regimes 2 and 4. The highest PO4 3- (97.2%) and NH4 + (71%) removal was reported in the R1 regime. None of the influent Cu2+ or Zn2+ was precipitated on the device. Conclusion: A higher struvite yield is evident in pH constant experiments. Moreover, the stainless steel device facilitates the isolation of heavy metal free pure (around 96%) struvite from swine waste biogas digester effluent contaminated with cu2+ and Zn2+ and the highest yield is attainable with the device operating at 50 rpm with agitation by a magnetic stirrer. [Copyright &y& Elsevier]

Objective: To investigate the heavy metals (HMs) and polycyclic aromatic hydrocarbons (PAHs) in sludge of twelve wastewater treatment plants (WWTPs) in Zhejiang province of China, and to assess their potential for land application. Methods: Sludge was collected from 12 WWTPs within the province. gc-ms and aas were used to measure PAHs and HMs contents in sludge. Results: Concentrations of HMs in most of the sludge samples were below the regulatory limits for the sludge to be used in agriculture in China with the exception of Zn in 2 sludge samples and Cd in 1 sample. All 16 PAHs, targeted by the usepa agency, were found in the sludge from the twelve plants with a total concentration ranging from 33.73 mg kg-1 to 82.58 mg kg-1 (dry weight, d.w.). The levels of Σ9 PAHs varied from 13.87 mg kg-1 to 61.86 mg kg-1 (d.w.) in the sludge, far exceeding the limitation value recommended by the Europe Union. The concentration and composition of PAHs in sewage sludge varied and depended mainly on the quantity and type of industrial wastewater accepted by the WWTPs. a significant relationship between the proportion of industrial wastewater received by WWTPs and the total content of 16 PAHs in the sludge was observed. Conclusion: PAHs have become one of the primary pollutants in sludge of Zhejiang WWTPs instead of HMs. It is, therefore, essential to reduce the contents of PAHs before the sludge can be used in agriculture through proper treatment. [Copyright &y& Elsevier]

Abstract: A field experiment located in Taihu Lake Basin of China was conducted, by application of urea or a mixture of urea with manure, to elucidate the interception of nitrogen (N) export in a typical rice field through “zero-drainage water management” combined with sound irrigation, rainfall forecasting and field drying. N concentrations in floodwater rapidly declined before the first event of field drying after three split fertilizations, and subsequently tended to return to the background level. Before the first field drying, total particulate nitrogen (TPN) was the predominant N form in floodwater of plots with no N input, dissolved inorganic nitrogen (DIN) on plots that received urea only, and dissolved organic nitrogen (DON) on plots treated with the mixture of urea and manure. Thereafter TPN became the major form. No N export was found from the rice field, but total nitrogen (TN) of 15.8 kg/hm2 was remained, mainly due to soil N sorption. The results recommended the zero-drainage water management for full-scale areas for minimizing N export. [Copyright &y& Elsevier]

The application of nitrogen fertilizers leads to various ecological problems such as nitrate leaching. The use of nitrification inhibitors as nitrate leaching retardants is a proposal that has been suggested for inclusion in regulations in many countries. In this study, using a multi-layer soil column device, the influence of new nitrification inhibitor DMPP (3,4-dimethyl pyrazole phosphate) was studied for understanding the nitrogen vertical transformation and lowering the nitrate leaching at different soil profile depths. The results indicated that, within 60 d of experiment, the regular urea added 1.0% DMPP can effectively inhibit the ammonium oxidation in the soil, and improve the ammonium concentration in soil solution over the 20cm depths of soil profile, while decline the concentrations of nitrate and nitrite. No obvious difference was found on ammonium concentrations in soil solution collected from deep profile under 20cm depths between regular urea and the urea added 1.0% DMPP. There was also no significant difference for the nitrate, ammonium and nitrite concentrations in the soil solution under 40cm depths of soil profile with the increasing nitrogen application level, among the treatments of urea added 1.0% DMPP within 60 d. It is proposed that DMPP could be used as an effective nitrification inhibitor in some region to control ammonium oxidation and decline the ion-nitrogen leaching, minimizing the shallow groundwater pollution risk and being beneficial for the ecological environment. [Copyright &y& Elsevier]

Abstract: The role of rhizosphere bacteria in facilitating the solubility of copper (Cu) in contaminated soil and Cu accumulation in plant were studied. The bacteria strains were isolated from the rhizosphere of Elsholtzia splendens, a Cu accumulator growing on Tonglu Mountain copper mines. After the sandy soils containing 237 mg kg−1 were incubated with the bacteria strains, it was indicated that rhizosphere microbes played an important role in influencing the availability of water-soluble Cu in soils. Soils had greater concentrations of water-extractable Cu compared with axenic soils inoculated with different bacterial strains. Further evidence for bacterial facilitation of increased solubility of Cu in the soil was obtained using the antibiotic ampicillin (0.1 mg g− 1). There were 36% decreases in Cu concentration in the presence of bacterial strain MS12 and ampicillin together compared with bacterial inoculation alone. Different bacterial strains had different abilities on soil water-soluble Cu. To achieve the highest rates of plant Cu accumulation, it was necessary for bacteria to be present in the rhizosphere of E. splendens. Inoculated plants supplied with 20 μmol L− 1 CuSO4 had significantly greater concentrations of Cu in shoots and roots than uninoculated plants and bacterial strain MS2 was the most effective strain in promoting plant Cu uptake. There were 2.2-fold and 2.5-fold increases in Cu accumulation in the shoots and roots of plants inoculated with strain MS2 compared to axenic controls. Furthermore, when ampicillin and the bacterial strains were added together to the nutrient solution, the Cu concentrations in roots and shoots of ampicillin-treated plants were lower than those in inoculated plants. When ampicillin was added to the nutrient solution, Cu accumulation was inhibited by about 24–44% in shoots and 20–44% in roots. The above results provided a new insight into the phytoremediation of Cu-contaminated soil. [Copyright &y& Elsevier]

Abstract: Biological removal of ammonia was investigated using two types of packing materials, compost and sludge in laboratory-scale biofilters (8l reactor volume). The aim of this study is to investigate the potential of unit systems packed with these supports in terms of ammonia emissions treatment. Experimental tests and measurements included analysis of removal efficiency, metabolic products, and results of long-term operation. The inlet concentration of ammonia applied was 20–200mgm−3. The ammonia loading rates of 24.9–566gNH3m−3d−1 to compost biofilter (BF3) and 24.9–472gNH3m−3d−1 to sludge biofilter (BF4) were applied for 210 days, respectively. Removal efficiencies of the compost and sludge biofilters were in the range of 97–99% and 95–99%, respectively when the inlet concentration of ammonia was below 110mgm−3, and the maximum elimination capacities were 288 and 243gNH3m−3d−1, respectively. However, removal efficiency and elimination capacity of both biofilters significantly decreased as the inlet concentration increased to above 110mgm−3. By using kinetic analysis, the maximum removal rate of ammonia, Vm, and the saturation constant, Ks, were determined for both packing materials and the value of Vm for compost was found to be larger. Periodic analysis of the biofilter packing materials showed the accumulation of the nitrification product in the operation. During the experiment, the pressure drops measured were very low. The use of both packing materials requires neither nutritive aqueous solution nor buffer solution. [Copyright &y& Elsevier]

The start-up and performance of the anaerobic attached film expanded bed (AAFEB) reactor with pre-aeration of carrier were investigated. The carriers of the reactors had been aerated for 10 days before they were put into the AAFEB reactors. The results indicated that the reactors advance the start-up by 15 days, and maintain higher efficiency when they were subjected to organic and hydraulic loading shock, but during steady-state operation, the reactors did not show better performance than the control reactors without pre-aeration of carrier. The thicker biofilm and higher biomass concentration of the reactors with pre-aeration were observed during the start-up period, but the difference between two types of reactors tapered with the time course, and at the steady-state operation, the difference between two types of reactors on these two parameters was not obvious. Maximum specific methane or acids production rates, dehydrogenase activity and coenzyme F420 content were continuously higher than those of the control reactors. After running 30 days, filamentous bacteria dominated in the reactors with pre-aeration, whereas the cocci were predominant species in the control reactors. It was suggested that the action of the biofilm is strongly dependent on the biofilm thickness or the biomass concentration in normal circumstances, but under adverse circumstances, such as organic or hydraulic loading shock, the characteristics and activity of the anaerobic granular sludge play key roles on the reactor performance. These results clearly indicated that pre-aeration of carrier favor to enhance the start-up and performance of AAFEB reactor. [Copyright &y& Elsevier]

To gain information on organic pollutants in water–sediment systems, a compartment model was applied to study the sorption course of phenanthrene and pentachlorophenol (PCP) in sediments. The model described the time-dependent interaction of phenanthrene and PCP with operationally defined reversible and irreversible (or slowly reversible) sediment fractions. The interactions between these fractions were described using first order differential equations. By fitting the models to the experimental data, apparent rate constants were obtained using numerical optimization software. The model optimizations showed that the amount of reversible phase increased rapidly in the first 10 d with the sorption time, then decreased after 10 d, while the amount of irreversible phase increased in the total sorption course. That suggested the mass transport between reversible phase and irreversible phase. The extraction efficiency with hot methanol ranged from 36% to 103% for phenanthrene and from 65% to 101% for PCP, with the trend of decreasing with sorption time. [Copyright &y& Elsevier]

A novel tri-primer polymerase chain reaction method (TP-PCR) was developed for the construction of a fused fpg gene, in which no endonuclease and ligase were used. Instead, two templates and three specifically designed primers were applied. Results showed that pheB and gfp genes, which encodes the catechol 2, 3-dioxygenase and the green fluorescent protein (GFP), respectively, were successfully fused into an fpg gene through the rapid TP-PCR system, indicating that TP-PCR method could be a useful tool for DNA fragment fusion in which no proper endonuclease sites were available. [Copyright &y& Elsevier]

The partitioning behavior of pentachlorophenol (PCP) in five sediments was studied using equilibrium sorption experiments and multiple cycles of sorption and desorption experiments. The results of the equilibrium sorption experiments showed that the isotherms of PCP on five sediments were linear and the partitioning coefficients (Kd) were proportional to the organic carbon content of the sediments. The average organic carbon content normalized partitioning coefficient (logKoc) of five sediments was 2.83±1.48. In multiple cycles of sorption and desorption experiments, the five sediments were found to exhibit statistically significant sorption–desorption hysteresis, and the hysteresis indices (HI) varied over a wide range (0.72–11.82). Correlations between the HI value and the percentage of lipid in the total organic matter in the sediment indicated that lipid was the main fraction to affect the hysteresis phenomenon, i.e., the higher the lipid percentage the greater the HI value. The hysteresis phenomenon was mostly caused by irreversible sorption of PCP on lipids, including entrapment by lipids, which induced the slow desorption rate from the sediment. Because of hysteresis in the sorption and desorption, the PCP ecological toxicity would be lower than expected. [Copyright &y& Elsevier]

In this paper, downward movement of phosphorus and copper as dredged sediment applied on sandy loam soil was studied by column leaching experiments. Three sediment application rate, (i.e., 1, 2 and 5-cm depth of sediments) were applied to the top of the soil columns. Two and a half months leaching experiments were conducted, which include a 15-day un-watered period. Concentrations of phosphorus and copper in the leachate and the vertical distribution of Olsen-P and diethylenetriaminepentaacetic acid (DTPA) extractable Cu in the soil columns were determined. The results showed that, un-watered period could increase the downward movements of phosphorus and copper. Sediment application significantly increased Olsen-P concentration in the top 15 cm of the soil columns, but has not significantly affected that in the deeper soil layer. The 1-cm depth sediment treatment did not increase the DTPA extractable Cu concentration in the whole soil column. The 5-cm depth sediment treatment, however, significant increased the DTPA extractable Cu in the deeper soil layers. This study suggested that the application of dredged sediment laden with P and Cu on sandy loam soil might cause the significant downward movement of phosphorus and copper. [Copyright &y& Elsevier]

Sensitive detection of ochratoxin A (OTA) plays an important role in the field of food safety control. In this study, we are reporting for the first time an electrochemical biosensor which employs the integration of MoSe 2 nanoflowers, Au nanoparticles (AuNPs), aptamer and the guanine-rich complementary DNA sequence for the sensitive detection of OTA. MoSe 2 nanoflowers are prepared by a simple hydrothermal method and used as a promising sensing platform based on its large surface area. The methylene blue is used as a tracer and a guanine-rich complementary DNA sequence is designed to bind with the unbound OTA aptamer for signal amplification. The aptamer is immobilized on the AuNPs/MoSe 2 modified electrode surface through Au–S interaction. Since OTA can competitively bind with the aptamer due to their high affinity, the presence of OTA will induce the decrease of guanine-rich DNA on the electrode surface, in turn reduces the signal of methylene blue which can specifically adsorb to the guanine units of DNA. The proposed assay shows a good linear relationship within the range of 0.0001–1 nM with a detection limit of 0.08 pM for OTA. The developed biosensor has been applied to determine OTA concentration in wine samples. [ABSTRACT FROM AUTHOR]

Abstract: A rapid toxicity test based on inhibition of esterase activity in the harmful freshwater microalgae –Microcystis aeruginosa was developed using flow cytometry. The hydrolysis rate of fluorescein diacetate (FDA) by intracellular esterase to fluorescein was used to indicate the metabolic activity of algae. Uptake of FDA was optimized at different concentrations and incubation times. Propidium iodide (PI) was utilized to assess cell membrane integrity. The optimized FDA/PI staining dosages were 10mg/L and 10μM, respectively, lower than the reported concentrations. Correspondingly, the proper incubation time was 14–21min at the optimal FDA dosage determined in this study. A new procedure based on optimized FDA/PI condition, called “whole algal culture flow cytometry with fluorescence triggering”, was developed for short-term bioassays. This new procedure, taking account of working conditions such as pH and impure cultures, is able to avoid algal cell damages in sample preparation and separate algal cells from non-algal particles by fluorescence triggering. This newly-developed procedure was then used to assess the toxicity of copper on M. aeruginosa in a short-term exposure (36h). As copper concentrations increased, it was found that the esterase activity decreased in a concentration-dependent manner with increased membrane fragments. Moreover, esterase activity was a good indicator of copper toxicity in M. aeruginosa. The EC50 value based on mean fluorescence intensity (MFI) was 123.3μg/L (95% confidence limits 101.5–146.2μg/L). Therefore, the new-developed procedure could be used for sublethal endpoints detection, and has the potential to be a rapid and cost-effective bioassay for selecting M. aeruginosa control methods or exploring the M. aeruginosa activity inhibition mechanism. [Copyright &y& Elsevier]

Abstract: Three Upflow Anaerobic Sludge Blanket (UASB) reactors were compared for Anammox enrichment using synthetic wastewater with Spherical Plastic (SP) and Bamboo Charcoal (BC) addition, and without carrier (CK). After four months of operation, the Anammox activity occurred in all reactors allowing continuous removal of ammonium and nitrite. Ammonium and nitrite removal efficiencies were all higher than 98% in steady phase with the effluent concentrations below 1mgL−1. The start-up time could be shortened from 117 to 97d in CK and SP reactor to 85d in BC amendment reactor. Quantitative PCR (q-PCR) analyses indicated a significant increase in the number of Anammox bacteria in BC amended reactor as compared with CK and SP during the entire start-up periods. The copy numbers of Anammox of 16SrRNA gene in the reactor with BC amendment could reach up to 6×109 copiesg−1 Volatile Suspended Solids, around 22.5times and 12.3times greater than that in CK and SP reactor, respectively. BC addition could accelerate the start-up of Anammox and significantly increase the Anammox bacteria number. [Copyright &y& Elsevier]

Abstract: Ex situ nitrification followed by denitrification inside the landfill has been recommended to remove ammonia from leachate. The effects of increasing nitrate load and decreasing organic carbon content in the injected leachate on the denitrifying capacity of municipal solid waste (MSW) were investigated. Results showed that MSW possesses a high denitrification capacity. Nitrate reduction could be initiated within 48h after the first addition of nitrate. Nitrate reduction rate increased with the increasing nitrate loading concentration. When the nitrate loading concentration was increased to 850mgL−1, nitrate reduction rate reached up to 35mgL−1 h−1. Nitrite accumulation could be found after the addition of nitrate in each test. However, the maximum nitrite accumulation efficiency declined with increased nitrate load. Organic carbon played an important role in the reduction of nitrate, and both endogenous and exogenous organic materials could act as electron donors. [Copyright &y& Elsevier]

Abstract: A pilot program concerning source separation of household waste was launched in Hangzhou, capital city of Zhejiang province, China. Detailed investigations on the composition and properties of household waste in the experimental communities revealed that high water content and high percentage of food waste are the main limiting factors in the recovery of recyclables, especially paper from household waste, and the main contributors to the high cost and low efficiency of waste disposal. On the basis of the investigation, a novel source separation method, according to which household waste was classified as food waste, dry waste and harmful waste, was proposed and performed in four selected communities. In addition, a corresponding household waste management system that involves all stakeholders, a recovery system and a mechanical dehydration system for food waste were constituted to promote source separation activity. Performances and the questionnaire survey results showed that the active support and investment of a real estate company and a community residential committee play important roles in enhancing public participation and awareness of the importance of waste source separation. In comparison with the conventional mixed collection and transportation system of household waste, the established source separation and management system is cost-effective. It could be extended to the entire city and used by other cities in China as a source of reference. [Copyright &y& Elsevier]

Municipal solid waste (MSW) source-classified collection represents a change in MSW management in China and other developing countries. Comparative experiments were performed to evaluate the effect of a newly established MSW source-classified collection system on the emission of PCDDs/Fs (polychlorinated dibenzo-p-dioxins and dibenzofurans) and heavy metals (HMs) from a full-scale incinerator in China. As a result of presorting and dewatering, the chlorine level, heavy metal and water content were lower, but heat value was higher in the source-classified MSW (classified MSW) as compared with the conventionally mixed collected MSW (mixed MSW). The generation of PCDDs/Fs in flue gas from the classified MSW incineration was 9.28ng I-TEQ/Nm3, only 69.4% of that from the mixed MSW incineration, and the final emission of PCDDs/Fs was only 0.12ng I-TEQ/Nm3, although activated carbon injection was reduced by 20%. The level of PCDDs/Fs in fly ash from the bag filter was 0.27ng I-TEQ/g. These results indicated that the source-classified collection with pretreatment could improve the characteristics of MSW for incineration, and significantly decrease formation of PCDDs/Fs in MSW incineration. Furthermore, distributions of HMs such as Cd, Pb, Cu, Zn, Cr, As, Ni, Hg in bottom ash and fly ash were investigated to assess the need for treatment of residual ash. [Copyright &y& Elsevier]

Abstract: Municipal solid waste (MSW) decomposition under oversaturated condition in comparison with leachate recirculation was investigated in two simulated reactors (A and B). Reactor B was operated with leachate recirculation while in reactor A, an oversaturated condition was maintained without leachate recirculation. Results showed that MSW decomposition in reactor A was much faster than that in reactor B. The final CODcr concentration and pH value of leachates in reactor A were around 1000mgL−1 and 7.0, respectively, in comparison to 18,000mgL−1 and below 6.5 in reactor B after 420 days of incubation. Biogas production was positively related to ambient temperature. The total biogas and methane yields were 2800L and 1330L in reactor A while only 1470L and 600L in reactor B. These results indicated that the relative retardation of MSW degradation in reactor B was primarily resulted from the increased resistance of mass transfer and the accumulation of biogas caused by leachate recirculation and the resultant acid inhibition. Bioreactor landfill operated under liquid oversaturated and MSW loose condition could be a promising approach for accelerating municipal solid waste degradation. [Copyright &y& Elsevier]

Abstract: All the regulations that define a maximum concentration of metals in the receiving soil are based on total soil metal concentration. However, the potential toxicity of a heavy metal in the soil depends on its speciation and availability. We studied the effects of heavy metal speciation and availability on soil microorganism activities along a Cu/Zn contamination gradient. Microbial biomass and enzyme activity of soil contaminated with both Cu and Zn were investigated. The results showed that microbial biomass was negatively affected by the elevated metal levels. The microbial biomass-C (Cmic)/organic C (Corg) ratio was closely correlated to heavy metal stress. There were negative correlations between soil microbial biomass, phosphatase activity and NH4NO3 extractable heavy metals. The soil microorganism activity could be predicted using empirical models with the availability of Cu and Zn. We observed that 72% of the variation in phosphatase activity could be explained by the NH4NO3-extractable and total heavy metal concentration. By considering different monitoring approaches and different viewpoints, this set of methods applied in this study seemed sensitive to site differences and contributed to a better understanding of the effects of heavy metals on the size and activity of microorganisms in soils. The data presented demonstrate the relationship between heavy metals availability and heavy metal toxicity to soil microorganism along a contamination gradient. [Copyright &y& Elsevier]

Bioremoval of trimethylamine (TMA) in two three-stage biofilters packed with compost (A) and sludge (B), respectively, was investigated. Both biofilters were operated with an influent TMA concentration of 19.2–57.2mgm−3 for 67 days. Results showed that all of the inlet TMA could be removed by both biofilters. However, removal efficiency and transformation of TMA in each section of both biofilters was different. In the Introduction section, TMA removal efficiency and maximum elimination capacity of the compost medium were greater than those of sludge medium under higher inlet TMA concentration. In comparison with biofilter A, considerably higher NH3 concentrations in effluent of all three sections in biofilter B were observed after day 19. Although, NO2 −-N concentration in each section of biofilter A was relatively lower, NO3 −-N content in each section of biofilter A increased after day 26, especially in the Materials and method section which increased remarkably due to a lesser amount of TMA and higher ammonia oxidation and nitrification in compost medium. In contrast, neither NO2 −-N nor NO3 −-N were detected in either section of biofilter B at any time throughout the course of the experiment. The cumulative results indicated that compost is more favorable for the growth of TMA-degrading and nitrifying bacteria as compared to the sludge and could be a highly suitable packing material for biodegradation and transformation of TMA. [Copyright &y& Elsevier]