南方,中水回用的空间

从2000年《中共中央关于制定国民经济和社会发展第十个五年计划的建议》，首次提出了建设“节水型社会”构想，到“十一五”规划时期建设节水型社会的实施与发展，建设节水型社会逐渐被公众所广泛接受。建设节水型社会的核心是提高用水效率。在创建节水型社会的今天，各种节水措施都应该被广泛应用，最终形成合力，把一个节水型社会建没起来。其中，中水回用也应作为一个有益的、不可忽视的节水方式。     

烟酰胺降解菌的筛选及其降解特性

采用HPLC对某烟酰胺生产废水的主要成分进行分析,并模拟废水中的主要成分烟酰胺(nicotinamide)的浓度,对以烟酰胺为唯一碳源配制的培养基进行降解实验,获得有较佳降解率和生长能力的菌株YSI-1和YSI-2.结果表明,YSI菌株的混合菌降解效果优于单株菌,混合菌在初始OD600值为0.4,pH为7.0时,对浓度为2000 mg/L的烟酰胺降解2 d的降解率可达32.8%.延长处理时间或提高菌种的初始OD600值,烟酰胺的去除率均有较大的增加.     

Treatment of atrazine by integrating photocatalytic and biological processes

This research examines the degradation of atrazine by photocatalytic oxidation (PCO) under different experimental conditions. Deisopropylatrazine, deethylatrazine and deethyldeisopropylatrazine were formed as major intermediates based on gas chromatography-mass spectrometry. The reaction mixture was found to be toxic towards two bioassays, i.e. the Microtox and amphipods survival tests even when atrazine was completely degraded by PCO within 2 h under optimized conditions. The results indicate that adding H2O2 could significantly enhance the degradation of atrazine by PCO. Ammeline, ammelide and cyanuric acid (CA) became the major intermediates/products as detected by high performance liquid chromatography from 6th to the 40th h of PCO treatment. After 72 h PCO treatment, only CA was detectable in the reaction mixture. Further degradation of CA was carried out by a newly isolated CA-degrading bacterium, Sphingomonas capsulata. The photochemical pretreatment integrated with microbial degradation lead to the complete degradation and detoxification of atrazine.     

Physiological aspects of vetiver grass for rehabilitation in abandoned metalliferous mine wastes

Physiological aspects of why vetiver grass (Vetiveria zizanioides L.) can be tolerant to heavy metals and be used as an alternative method for rehabilitation of abandoned metalliferous mine wastelands have been investigated. The results showed that high proportions of lead and zinc (Pb/Zn) tailing greatly inhibited the leaf growth, dry matter accumulation, and photosynthesis of leaves, but stimulated the accumulation of proline and abscisic acid (ABA), and enhanced the activities of superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT), implying that different mechanisms to detoxify active oxygen species (AOS) existed in different parts of plants. Physiological responses to heavy metal treatments differed greatly between roots and shoots. Nitrogen fertilizer application could greatly alleviate the adverse effects of high proportions of Pb/Zn tailing on vetiver grass growth.     

Effects of leachate recirculation on biogas production from landfill co-disposal of municipal solid waste,sewage sludge and marine sediment

Leachate recirculation is an emerging technology associated with the management of landfill. The impact of leachate recirculation on the co-disposal of three major wastes (municipal solid waste, sewage sludge and sediment dredgings) was investigated using a laboratory column study. Chemical parameters (pH, COD, ammoniacal-N, total-P) and gas production (total gas volume, production rates and concentrations of CH4 and CO2) were monitored for 11 weeks. Leachate recirculation reduced waste-stabilization time and was effective in enhancing gas production and improving leachate quality, especially in terms of COD. The results also indicated that leachate recirculation could maximize the efficiency and waste volume reduction rate of landfill sites.     

Modeling the reaction kinetics of Fenton's process on the removal of atrazine

The degradation of pesticide, atrazine (ATZ), 2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine, by Fenton's reagent (FR) was investigated as a function of reagents' concentrations and ratios in a batch reactor. The degradation of ATZ was effectively achieved by hydroxyl radicals, which were generated in the FR process. The decay rates of ATZ and the oxidation capacities of FR were found to depend on the concentrations of hydrogen peroxide and ferrous ion. The removal kinetics of ATZ are initiated by a rapid decay and then followed by a much slower one. After an extended reaction time (5-10 min), the reactions ceased because the Fe(II) and H(2)O(2) were consumed and would be deactivated in the process. A mathematical model was successfully developed to describe the two-stage reaction kinetics by using two simple but critical parameters: the initial ATZ decay rate and the final oxidation capacity of Fenton's process. In general, higher [Fe(II)] or H(2)O(2) concentrations result in faster initial decay rate and higher oxidation capacity. However, the oxidation capacity is more sensitive to the initial [Fe(II)] due to the presence of side reactions as discussed in the paper.     

Nitrous oxide flux from landfill leachate-sawdust nitrogenous compost

Composted nitrogenous waste has the potential to produce excessive amounts of nitrous oxide (N2O), a potent greenhouse gas that also contributes to stratospheric ozone depletion. In this laboratory study, sawdust was irrigated with varying amounts of landfill leachate with high NH4+-N content (3950 mg l(-1)). Physicochemical properties, including the amount of N2O produced, were monitored during the composting process over 28 days. A rapid decline in NH4+-N in the first 4 days and increasing NO3--N for 11 days was followed by lower but stabilized levels of available-N, even with repeated leachate irrigation. Less than 0.03% of the leachate-applied N was lost as N2O. Higher leachate applications as much as tripled N2O production, but this represented a lesser proportion overall of the total nitrogen. Addition of glucose to the composting process had no significant effect on N2O production. The derived sawdust-leachate compost supported healthy growth of Sesbania rostrata. It is concluded that compost can be produced from sawdust irrigated with landfill leachate without substantial emission of N2O, although excessive flux of N2O remains about high application rates over longer time periods.     

An unconventional approach to studying the reaction kinetics of the Fenton's oxidation of 2,4-dichlorophenoxyacetic acid

The Fenton's oxidation kinetics of herbicide 2,4-D at various [Fe(II)] and [H(2)O(2)] combinations was investigated and modelled through an unconventional approach. The reaction kinetics of 2,4-D degradation demonstrated a two-stage pattern of decay, where a very fast reactive stage was followed by a retardation stage due to the depletion of oxidants and to the competitive side-reactions of the intermediates (including 2,4-dichlorophenol, chlorohydroquinone and 2,6-dichlororesorcinol). A model characterized by two newly established constants, the initial decay rate and the maximum oxidative capacity, was proposed and proven capable of describing the two-stage process, which cannot easily be described by conventional first- or second-order kinetics approaches.