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Abstract: In view of the existing technical problems about treatment of heavy metal pollution, a new organic heavy metal chelator—dipropyl dithiophosphate has been developed. This paper focuses on the mechanism about the laboratory synthesis of dipropyl dithiophosphate and chelate heavy metal, discusses the effects of pH value, added quantity of chelator, reactive time and coexistence of several heavy metal ions on the treatment effectiveness, and compares the stability of chelate complex with conventional neutral precipitation method. The results of the experiment show that, within the scope of pH 3–6, for the wastewater with the concentration of lead, cadmium, copper and mercury being 200mg/L, dipropyl dithiophosphate enjoys a removal rate about these elements up to over 99.9%, and the concentrations of the lead, cadmium, copper and mercury in the wastewater after treatment are less than 1, 0.1, 0.5 and 0.05mg/L, respectively, which meet the limit value of concentration stipulated in the Integrated Wastewater Discharge Standard (GB8978-1996). And the treatment effectiveness are not affected by pH value and coexistent heavy metal ions, which makes up the deficiency that neutral precipitation must be used under the condition of high alkalinity. The optimum quantity of dipropyl dithiophosphate chelator added is 1.2 times as much as stoichiometric amount and the optimum reactive time is 20min for lead, cadmium and copper, and 30min for mercury. Within the scope of pH 3–9, each heavy metal ion release of chelate complex will decrease along with increased pH value. But under any pH conditions, the release of heavy metal ions in hydroxide is far higher than that in chelate complex, therefore reducing the risk of polluting the environment again. [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: A competitive enzyme-linked immunosorbent assay (ELISA) was developed to determine vitellogenin (Vtg) in rare minnow (Gobiocypris rarus) based on the separation and purification of rare minnow Vtg (r-Vtg) as well as the production of polyclonal antibody against r-Vtg in rabbits. Three different ELISAs for measuring r-Vtg were then compared: (1) indirect ELISA with the antibody against carp (Cyprinus carpio) Vtg (c-Vtg) (IC-ELISA); (2) competitive ELISA with the antibody against c-Vtg, and using r-Vtg for coating the plates and preparing standard curve (CC-ELISA); (3) competitive ELISA with the antibody against r-Vtg, and using r-Vtg for coating the plates and preparing standard curve (CR-ELISA). The result showed that the homologous CR-ELISA was the most sensitive among the three assays for quantifying r-Vtg. The sensitivities to 17α-ethinylestradiol (EE2) of rare minnow and zebrafish (Danio rerio) were compared upon the establishment of homologous competitive ELISA. The lowest observed effect concentrations (LOECs) to induce Vtg were found to be 0.8 ng EE2 l−1 for rare minnow and 4 ng EE2 l−1 for zebrafish respectively. Afterwards, CR-ELISA was applied to measure Vtg concentration in whole body homogenate (WBH) of juvenile rare minnow fed by three diets (tubifex from wastewater treatment plant, Artemia nauplii and commercial pellet food), and the agreements between bioassay and GC–MS analysis demonstrated that rare minnow was a sensitive fish model for assessing estrogenic effects of endocrine disrupting compounds in aquatic environment. [Copyright &y& Elsevier]