In this study, a novel and integrated hydrometallurgical process for the production of zinc powder from electric arc furnace (EAF) dust in alkaline medium is reported. The dust is firstly hydrolysed in water, and then fused in caustic soda at 350 C for 1 h, followed by leaching in alkaline solution in which both zinc and lead are effectively extracted. Zinc powder is then produced by electrowinning from the leach solution after the lead is selectively removed by precipitation using sodium sulphide as precipitant. The EAF dust tested contained 25% Zn, 1.8% Pb and 33% Fe. It was found that 38% of zinc and 68% of lead could be extracted from the dust when leached directly in caustic soda solution. Leaching of zinc increased to 80% when dust was directly fused with caustic soda followed by alkaline leaching. However, the leaching further increased to 95% when the dust was hydrolysed first with water before fusion. Zinc powder with a purity of 99.95% was then produced by electrowinning from the lead depleted solution. Stainless electrodes were used as both anode and cathode.

In this work, the impact of moisture on the volatility of heavy metals present in municipal solid wastes (MSW) in a laboratory scale simulated incinerator was studied, using synthetic waste consisting of 5.4 g of wood powder, 2.6 g lava, 1.9 polythene, 0.19g polyvinyl chloride, and a given quantity of water and heavy metals represented by lead, zinc and copper in forms of metallic, chlorides and oxides. It is found that the presence of high moisture in MSW will greatly reduce the volatilization of heavy metals in MSW in the incineration process. The volatilization behavior of chlorides, oxides and the metallic species with respect to the effect of moistures is quite dierent. For copper, the presence of moisture in MSW depresses the volatilization of oxides, and increases that of chloride and the metallic species, while in contrast, the volatilization of both lead and zinc is always depressed by the presence of moisture in MSW, regardless of the chemical forms used. The chemical mechanisms, which govern the volatilization behaviors of dierent chemical forms in the incineration process, are proposed. Hydrolysis, dewatering of hydrolyzed species, sublimation, chemical transformation of less volatiles to more volatiles or reverse, may participate in and aect the volatilization of heavy metals in MSW.

A mixed bacterial population was isolated using enrichment in a basal medium containing increasing amounts of fenoxaprop-p-ethyl as a sole carbon source from sludge that had been exposed to fenoxaprop-p-ethyl production wastewater for about 2 years. Eight kinds of isolates could utilize fenoxaprop-p-ethyl, but only one was identified belonging to genus Alcaligenes, named Alcaligenes sp. H. In pure culture, there was 45.8, 66.0 and 69.5% loss of fenoxaprop-p-ethyl (initial concentration: 100, 50, 25 ppm, respectively) as the sole carbon source with biodegradation by Alcaligenes sp. H and fenoxaprop-p-ethyl degradation kinetics obeyed the first-order kinetics, the same as the fenoxaprop-p-ethyl biodegradation kinetics in soil. At least five degradation products of fenoxaprop-p-ethyl biodegradation by Alcaligenes sp. H and two degradation products of fenoxaprop-p-ethyl biodegradation by Huv separated by HPTLC. It is possible that the fenoxaprop-p-ethyl biodegradation by Alcaligenes sp. H includes the same pathway as that by Huv comparing with the Rf.

Zinc and lead are usually concomitantly present in Zn-Pb ores and solid wastes, such as electric arc furnace (EAF) dusts. One of the treatment methods is to extract zinc and lead from the ores and wastes by an alkaline leaching process if applicable. The selective and quantitative separation of lead from zinc is an important step in these processes. In this work, the separation of lead from zinc in alkaline zinc solution, in leaching solutions of EAF dusts, and in oxidized zinc ores by sodium sulfide precipitation was studied. When the weight ratio of sodium sulfide (average molecular weight 222) added to the lead present in alkaline solution was over 1.8-2.0 (molar ratio approximately 1.5-1.7), lead could be separated selectively and quantitatively, while the zinc remained in the solution without concomitant loss. The residues from the precipitation step were identified as mixtures of PbS and Na2Pb (OH)2S, with PbS being the predominant compound.

全面综述了垃圾组成、垃圾水分含量、垃圾坝处理与填埋操作方式、填埋场地水文气象条件，渗滤液pH值与氧化还原电位及微生物种群等填埋场稳定化的影响因素。

Refuse in landfills becomes stabilized or aged, as organic matter in the refuse gradually degrades and as the soluble inorganic substances dissolve during its long-term stabilization process. Within this paper, this process is referred to as mineralization and the resultant stabilized or essentially stabilized refuse is referred to as "aged refuse."The aged refuse contains a wide spectrum and large quantity of microorganisms, which have a strong decomposition capability for refractory organic matter present in some wastewaters, such as leachate. In this study, aged refuse excavated from two to ten year old closed landfill compartments in Shanghai Refuse Landfill (SRL) was characterized in terms of particulate distribution by screening, and a biofilter consisting of ten year old aged refuse was then used for biofiltration of leachate sampled from the landfill. Typically, 400 kg of screened aged refuse with limiting diameter less than 15 mm was used as biofiltration materials in a round shaped biofilter with 80 cm inner diameter and 80 cm height. Leachate with initial chemical oxygen demand (COD), biological oxygen demand (BOD), and NH3-N concentrations of 3,000-7,000, 540-1,500, and 500-800 mg/L, respectively, was passed through the biofilter. As a result, the corresponding concentrations in the effluent were reduced to lower than 100-350, 10-200, and 10-25 mg/L, respectively, 90-99% removal for these parameters at a hydraulic load of 80-200 L/m3 refuse/day. The color of the effluent became slightly gray, in comparison with the heavy brownish color of the influent. The treatment efficiencies heavily depend on hydraulic load, BOD/COD ratios in the leachate, and preliminary treatment of the aged refuse. A variety of leachates with various BOD/COD ratios was tested. It was found that the effluent deteriorated when BOD/COD ratios were lower than 0.1-0.2. Increase of hydraulic load resulted in a decrease of removal efficiencies. Removal of stone, plastics, and glass, etc., from the aged refuse improved the treatment. A pilot test was conducted at SRL and the experimental results obtained at laboratory scale were verified.

对分类收集的城市生活有机垃圾采用专门设计的兼氧沤解预液化一常温厌氧消化的工艺技术进行处理。试验结果显示，兼氧抠解对生活有机垃圾的预液具有较好的效果，液化率达80%以上，可以满足反应器对生活有机垃圾预处理的要求。

In this work, a production process for Zn powder by alkaline treatment of an oxidized Zn ore, smithsonite ZnCO, was studied. It was found that over 85% of both Zn and Pb, and less than 3 10% of Al can be leached from the ore when the leaching operation is conducted at over 958C using 5 M NaOH solution as leaching agent. The dissolution of impurities such as Fe, Ca, etc., was negligible. Leaching of Pb can be improved remarkably with addition of NaCl to the leaching systems. Typical composition of the leach solution is 22-25 grL Zn, 2.96-3.05 grL Pb and 0.5-0.7 grL Al. Zn and Pb contents in the leaching residue were found to be lower than 2.4% and 0.05-0.2%, respectively. Pb present in the leach solution is separated with the addition of sodium sulfide. The Pb-free solution is then used for the electrolysis of metallic Zn using stainless steel electrodes. Zn metal powder with purity higher than 99.5% is obtained. The specific energy for the Zn electrolysis in alkaline leach solution is around 2.4-2.6 kWhrkg Zn, which is lower than the energy consumption of 3.3 kWhrkg Zn required in the conventional process of Zn electrolysis in acidic sulfate electrolytes. The process developed is considered to be cost-effective, simple and easy to be operated and managed, and the flowsheet for the production of Zn from ores is presented. It is proposed that ores be broken into particles smaller than 0.1-0.5 mm. Then, w leached with 5 M NaOH solution at a 90-958C temperature for 1.5 h at a phase ratio NaOH. x solution added ml to the ore leached g of 6-7. After filtration, the leach solution is subjected to electrolysis for the production of metallic Zn after Pb is separated by sodium sulfide. The NaOH solution is recycled to the next leaching operation after most of the Zn is electrowon. To save energy and keep heat loss minimal, all operations can be conducted in an adiabatic environment, including leaching, filtration and electrolysis. Loss of NaOH was estimated to be less than 50 g for the production of 1 kg of Zn, assuming that most NaOH left in the leaching residues and precipitates of lead sulfide could be recovered by washing with dilute NaOH solution and water. However, loss of NaOH is dependent on the type and composition of the ores. The presence and leaching of silicates, carbonates and phosphates in ores would increase the loss of NaOH and deteriorate filtration of leach residues in the alkaline solutions. Therefore, most of the operational cost for this process comprises the consumption of electricity for electrolysis, NaOH, and energy required for heating.

Selective removal of SO2, H2S andNOx from gas streams (air or towngas) was investigated using aqueous solutions of 12-molybdophosphoric acid and its reduced molybdenum blue species. The experimental results showed that H2S and SO2 in the gas streams can be removed quantitatively by yellow solution of 12molybdophosphoric acid. The H2S was oxidized into recoverable elemental sulfur and SO2 into H2SO4, while the yellow solution was reduced into blue species (reduced molybdenum blue). The obtained reduced molybdenum blue solution was then used for the quantitative removal of NOx, which was reduced into N2 and the blue solution was then oxidized back into yellow species. It is possible that the regenration of scrubbing solution is not required and no chemical is consumed during absorption, when NOx, SO2 and/or H2S coexisted in wastegases and the molar ratios of NO2/(SO2+H2S) is just equal to 1/2, although, in most cases, the ratio in real practical wastegases is not always equal to the value. The absorption mechanism was studied in detail. It was found that only one olybdenum atom in 12molybdophosphoric acid was reduced from Mo (Ⅵ) to Mo (Ⅴ) by H2S or H2SO3 and the Mo (Ⅴ) was oxidized back into Mo (Ⅵ) in the case of Nox absorption. 12-molybdophsophoric acid used in this work is inexpensive, commercially available, easily regeneratable, relatively nontoxic, and gives no secondary pollutant in the process.

In this work, the relationship between heavy metal content of fly ash and that of the solid wastes incinerated was correlated and compared. It is found that the former is a function of the latter. Hence, it is important to prevent heavy metal-rich wastes from being incinerated in order to reduce the content of toxic metals in the fly ash. The leachability of fly ash from incineration was usually beyond the scope of toxicity standard and must be properly treated before discharge. Secondly, chemical stabilization for the heavy metals in fly ash was explored. Among the chemicals used, it was found that sodium hydroxide was not suitable for the adequate extraction of the heavy metals from the fly ash. Ethylenediaminetetraacetic acid disodium salt (EDTA) was also tested and seems to be effective for the leaching of toxic metals from the fly ash. On the other hand, sodium sulfide and thiourea are one of excellent chemicals for the effective treatment of fly ashes, since they convert soluble and leachable toxic metals into non-leachable and insoluble forms such as lead and zinc sulfide or their similar forms of thiourea. These chemical species are supposed to be stable in nature. A comparison between chemical stabilization noted above and cement or asphalt solidification methods is made. Chemical stabilization processes, especially using sodium sulfide as the chemical agent, are strongly recommended for the practical uses, in terms of the volume expansion and environmental safety of the stabilized products and cost balances, in comparison with the traditional cement or asphalt solidification methods.