剩余污泥减量化工艺条件优化研究

运用超声处理连续流活性污泥系统中不同种类的污泥,并将其回流至原系统中,研究其剩余污泥减量化效果。按正交实验设计并进行试验,确定最优工艺条件。结果表明:当声能密度为0.6 W/mL,作用时间为5 min,超声污泥为混合污泥,回流比为7∶120时,减量效果最佳。且在该条件下经一周期的运行,污泥减量效果达到96.24%,COD由进水的830 mg/L降至44 mg/L,NH4+-N和TN分别由进水的62.43 mg/L和103.19 mg/L,降解到2.31 mg/L和6.52 mg/L,达到《城镇污水处理厂污染物排放标准》(GB18918-2002)一级排放标准。     

北京和上海典型复合包装废物处置环境影响比较

采用生命周期评价法研究比较了北京和上海两地纸塑铝复合包装处置阶段的环境影响。通过现场和资料调研的方式获得此阶段的能量物质的输入输出和环境外排数据。结果表明:北京和上海两地纸塑铝复合包装处置阶段的环境影响潜值分别为-0.428 Pt和9.776 Pt,其主要集中在气候变化、土地占用和无机物对健康的损害三方面;每提高10%的回收率,其环境影响潜值北京和上海可分别降低5.446 Pt和5.799 Pt;上海地区纸塑铝复合包装处置阶段对环境的影响在任何同回收率的情况都要高于北京地区,其主要原因是上海地区填埋产生的温室气体释放量过大和再生企业距离打包点较远。     

危险废物处理技术进展及若干建议

较系统地论述了国内固体废物的目前状况、产量,分析了一些典型危险废物处理过程中存在的主要问题和解决方法,提出了深人开展危险废物处理与资源化研究的方向,并给出了环保部门应对危险废物进行处理的建议。     

中国农村经济制度变迁与农业周期性增长分析

农业增长除受到基本投入要素的影响,还受制度因素的影响。对于制度因素对农业增长的影响的研究,大多文献是从定性的角度分析。本文运用计量经济学和统计方法,通过对1978-2007年总体和不同阶段农业增长与农村土地制度、价格制度、财政制度和税费制度进行理论和实证分析,探讨制度变迁对农业生产总值增长的推动作用。文章通过分析发现,我国农业在要素投入并没有周期性变化的情况下,农业总产值增长率却呈现一定的周期性。为了探究农业周期性增长的原因,本文结合我国农村经济制度变迁的路径和农业总产值指数变化的特点,将改革开放以来我国农业增长分为三个阶段进行分析,同时根据Griliches生产函数构造计量分析模型。通过分析发现,正是由于不同阶段农村土地制度、价格制度、财政制度和税费制度的变迁,导致农业生产总值增长率周期性起伏。因此,制度变迁是改革开放后中国农业经济增长的内在决定性因素。     

农业化学品投入状况及其对环境的影响

农业生产中,农业化学品的大量使用产生了明显的负外部性影响,尤其是农业的面源污染问题随化肥、农药投入的增加而不断加剧。通过统计分析方法,对农业化学品投入数量及区域分布特征、农业化学品投入存在的问题及其所造成的面源污染问题进行分析。结果表明:化肥和农药总投入不断增加,其中河南、山东、江苏、安徽、湖北和湖南6省投入总额接近全国的一半;农业化学品使用存在过量投入、投入结构失衡和施肥施药技术落后等问题;农业化学投入品的过量使用造成的环境污染问题正不断加剧,农业面源污染排放对污染总量的贡献率不断上升。最后提出了相关政策建议,包括加强农业面源污染控制的政策框架和配套制度建设、推广成熟的化肥农药施用技术和加强农业环保教育。     

我国农产品贸易中的虚拟耕地交易分析

虚拟耕地是指隐含在农产品贸易中,生产这些农产品过程中所必需占用的土地资源,有意识的在国际农产品贸易中实施虚拟耕地战略,对于平衡国内耕地赤字、保障粮食安全,发挥我国农产品在国际市场上的竞争优势具有重要的理论指导意义。首先介绍了虚拟耕地的定义及其量化方法,接着分析计算了我国谷物、油籽、棉花等几类主要农产品单位重量的虚拟耕地含量,在此基础上,对当前农产品进出口贸易中虚拟耕地的交易现状及未来发展趋势作了分析和预测。结果显示：近10 a来虚拟耕地净进口量出现持续增长,2006年,通过农产品国际贸易净进口虚拟耕地16602903.1 hm²,约占当年全国耕地总面积的12.77%。同时,虚拟耕地净进口量在今后若干年仍将保持增长态势。     

Deposition of aerially sprayed mexacarbate on balsam fir canopy and the forest floor: Relevance to ULV applications

Abstract

Spray deposit patterns were measured on aluminum coils and live balsam fir needles at different canopy heights, following aerial application of mexacarbate (4‐dimethylamino‐3,5‐xylyl N‐methylcarbamate) over a conifer forest in New Brunswick. Droplet size spectra of the spray cloud were determined on cylindrical Kromekote® cards placed at the corresponding crown heights. Ground deposits were collected on cylindrical Kromekote cards, aluminum coils and natural balsam fir foliage placed In forest clearings and under different types of vegetation.

Canopy deposits decreased progressively from the top to the bottom level of the tree crown. This trend was observed on aluminum coils, live fir foliage, and Kromekote cards. Droplet size spectra were similar at all sampling heights of the tree crown, and were comparable to those obtained on the ground cards placed in the forest clearings. Deposits of mexacarbate obtained on ground samplers on the open forest floor were markedly lower than those found at the top canopy but were similar to those at the mid or bottom canopy level. Droplet size spectra and mexacarbate deposits obtained on samplers placed under different types of forest vegetation indicated a selective filtration of the large droplets present in the spray cloud by plant canopies.     

Biodegradation of α and β Endosulfan in Soil as Influenced by Application of Different Organic Materials

Abstract

A laboratory pot experiment was conducted to study the effect of amending soil with four different sources of organic matter on the degradation rate of α and β endosulfan isomers. Poultry by-product meal, poultry manure, dairy manure, and municipal solid waste compost were cured, dried, ground (<1 mm) and thoroughly mixed with a calcareous soil at a rate of 2% and placed in plastic pots. Endosulfan was added at the rate of 20 mg kg^?1. The moisture level was kept near field capacity and the pots were kept at room temperature. Soil sub-samples, 100 g each, were collected from every pot at days 1, 8, 15, 22, 29, 43, and 57 for the measurement of endosulfan isomers. Endosulfan residues were extracted from the soil samples with acetone. The supernatant was filtered through anhydrous sodium sulphate, 5 mL aliquot was diluted to 25 mL with hexane, mixed well, and then two sub-samples from the filtrates were analyzed for α and β endosulfan isomers by gas chromatography. The results indicated that the half-life (T _½) of α-endosulfan in the poultry by-product meal treatment was 15 days compared to about 22 days in the other treatments. The T _½ of β-endosulfan was 22 days in the poultry by-product meal treatment and followed a bi-phasic pattern, 57 days in the municipal solid waste compost treatment and the extrapolated T _½ was about 115 days for the other three treatments.     

Persistence,degradation and leaching of coumaphos in soil

Abstract

Dissipation, degradation and leaching of fresh ¹⁴C coumaphos, alkylated ¹⁴C coumaphos and aged residues of ¹⁴C coumaphos from vats were studied in alkaline sandy loam soil in soil columns in the field under subtropical conditions in Delhi for a year. Dissipation, degradation and bound residue formation was more in case of alkali treated coumaphos than fresh coumaphos. After 365 days total residues of fresh coumaphos accounted for 33.25% while that of alkali treated coumaphos was 19.12%. Bound residue formation was almost double in case of alkali treated coumaphos (18.95%) than fresh coumaphos (9.53%) after 150 days followed by release of bound residue in both the cases. The proportion of metabolites 4 ‐ methylumbelliferone, chlorferon and potasan collectively was 86.05% in fresh coumaphos extractable residues while the same was 91.74% in alkali treated coumaphos after 365 days. Aged residues from vats containing copper sulphate and buffer were found to be more persistent in soil as total residues remained were 95.58% in comparison with 83.09% total residues of aged residues from vats containing only buffer after 150 days of treatment. Copper sulphate seems to inhibit the degradatiion of coumaphos in soil by microorganisms. Chlorferon was the major metabolite in generally all the samples. Coumaphos did not leach below 10 cm in all the cases.     

废LCD面板有机材料水热资源化产乙酸

LCD面板主要由附着偏光片及液晶等有机材料的玻璃面板构成。有机材料的去除及资源化利用是废LCD面板处理的第一步。在水热条件下对废LCD面板进行了降解产酸研究。研究考察了反应温度、反应时间、氧化剂用量、水用量及pH值等对水热产乙酸产率及选择性的影响。通过正交实验确定了水热产乙酸的最佳操作条件：反应温度325℃,反应时间5min,氧化剂（30％H2O2）0．6mL,用水量2mL,近中性环境（pH6-6．5去离子水）。此条件下,乙酸产率及选择性分别为68．83％及70．56％。结果表明,以废LCD面板有机材料为原料,采用水热技术进行产乙酸反应,可实现其资源化再利用。