Simulation of substrate degradation in composting of sewage sludge

To simulate the substrate degradation kinetics of the composting process, this paper develops a mathematical model with a first-order reaction assumption and heat/mass balance equations. A pilot-scale composting test with a mixture of sewage sludge and wheat straw was conducted in an insulated reactor. The BVS (biodegradable volatile solids) degradation process, matrix mass, MC (moisture content), DM (dry matter) and VS (volatile solid) were simulated numerically by the model and experimental data. The numerical simulation offered a method for simulating k (the first-order rate constant) and estimating k₂₀ (the first-order rate constant at 20 °C). After comparison with experimental values, the relative error of the simulation value of the mass of the compost at maturity was 0.22%, MC 2.9%, DM 4.9% and VS 5.2%, which mean that the simulation is a good fit. The k of sewage sludge was simulated, and k₂₀, k_20s (first-order rate coefficient of slow fraction of BVS at 20 °C) of the sewage sludge were estimated as 0.082 and 0.015 d^?1, respectively.     

两种曝气设备的清水曝气充氧实验研究

根据清水充氧实验计算,比较了微孔雾化软管曝气和射流曝气的充氧动力效率和氧利用率.以及后续实验的结果,最终得出微孔曝气软管曝气是高效节能的河流整治方法.     

固定化包埋亚硝酸菌短程脱氮与同步除磷工艺研究

为实现常温下低碳源城市生活污水的低能耗脱氮除磷,采用固定化技术和厌氧/好氧/缺氧(AOA)工艺耦合与游离组进行了对比实验研究。在温度为25±1℃、pH为8.0±1、DO为1±0.5 mg/L和HRT为9 h的条件下,两组运行结果表明,固定组具有较高的硝化效率和较强的适应能力,亚硝氮的积累率可以稳定维持在70%以上,对NH4+-N、COD和TP的去除率分别为92.2%、87.2%和81.3%,明显优于游离组。     

成层土中考虑衰变作用的污染物迁移规律分析

针对一些有机污染物溶质具有衰变的性质以及土质衬里和地基土等存在着成层性的特点,建立了成层土中考虑衰变作用的污染物迁移计算模型,采用分离变量法获得了解析解,编制了相应的程序。通过对典型算例的计算,并与经典的GAEA Pollute软件的计算结果进行了对比分析,两者结果基本一致,证明了所提方法的正确性和可靠性。所提分析方法可供污染物填坑衬里初步设计参考。     

浅析思想政治教育的生态价值

胡锦涛总书记在十七大报告中指出,“建设生态文明,基本形成节约能源资源和保护生态环境的产业结构、增长方式、消费模式”。这一战略思想对中国的发展具有非常重要的意义。没有生态文明,一切文明就没有了享受的前提。思想政治教育不仅对经济政治文化建设有着重要的作用,而且在生态文明的建设过程中依然有重要的作用。加强思想政治教育生态价值的研究,对于缓解我国人口、环境、资源和能源等方面的压力以及我国生态文明建设,落实科学发展观有十分重大的意义。     

Use of oyster, Crassostrea gigas, and ambient water to assess metal pollution status of the charting coastal area, Taiwan, after the 1986 green oyster incident

Most of the oyster mariculture beds in Taiwan are in areas located along the west of the island. One of these areas is the Charting coast, where green oysters were found in 1986. During this incident, which became internationally notorious, mass mortality occurred in the Charting oyster beds. After this discovery, measures were taken by the authorities to counter pollution which lead to the problem. The effectiveness of these pollution control actions was evaluated in this study. Two water column indicators, particulate and sediment, and oysters were sampled and analyzed for metals (Cu, Zn, Pb, Ni) in Charting and its neighboring areas, Kuen-Shen Lake and Shin-Da Harbor, and the control area/station, Dah-Pen Wan. The current study shows that copper and zinc concentrations in both oysters and particulates significantly decreased in the Charting area, compared with concentrations found during the period of the green oyster incident. Six years after the incident, the copper concentration in oysters had fallen from a high of 4400 μg/g dry weight to an average of 300±69 μg/g dry weight, figures similar to the copper concentration in 1982. The pollution control actions taken after the incident are believed to be the cause of this recovery of the coastal environment. Nevertheless, Charting still produced oysters with the highest copper and zinc concentrations among the areas investigated. Further measures currently being taken by the government, including removing the sediment of some portions of Erhjin Chi, should be able to bring the oyster copper concentrations down to the levels similar to those observed in the neighboring area, (average concentration below 200 μg/g dry weight or all time maximum concentration below 500 μg/g dry weight).     

Combined treatment of phenolic wastewater by wet air oxidation and activated sludge

Wet air oxidation (WAO) is employed in this work for treating high concentration chemical wastewater containing phenol and/or phenolic compounds. Experimental results indicate that over 90% removal of phenol or phenolic compounds can be efficiently achieved in the WAO process. Despite of the high treatment efficiency of the WAO process, the treated wastewater, however, still retains relatively high chemical oxygen demand (COD) concentration and does not meet the safe discharge standard. Hence further treatment of the WAO treated wastewater by an aerobic biological treatment using acclimatized activated sludge is necessary. It is found in the present studies that the combined process, if appropriately operated, is capable of drastically reducing the COD concentration of the high concentration chemical wastewater to meet the safe discharge requirement. The operating conditions of the combined process are investigated to determine their respective effects on the overall treatment efficiency. The experimental data also indicate that the oxidation reaction can be represented by a first order kinetics in terms of the component or COD concentration. For both single component and multicomponent wastewaters, the WAO process was found to have different activation energy for oxidation below and above 200°C, suggesting possibly different reaction mechanisms between these temperature ranges. The experimental results provided in the present work can provide significant and practical information for optimizing the combined treatment method.     

Assessment of mutagenic potency of source water treated by ozone and adsorption processes

This research utilized the Ames test to determine the mutagenicity of water treated by advanced processes, including ozonation and granular activated carbon (GAC). Raw water samples for this research included those obtained from the Pan Hsin waterworks as well as samples containing humic acids. Treated samples were collected from the pilot‐scale advanced treatment plant. The Ames test was used to measure the mutagenicity of the water after each treatment process. For the Pan Hsin raw water samples treated with ozone or GAC, it was indicated that, regardless of whether samples were preozonated or not, they all showed a mutagenic potency less than 2 once the S9 enzyme was added. This level of mutagenicity is insignificant. The prepared humic acid samples, on the other hand, demonstrated a significant reduction in mutagenicity after the pre‐ozonation process, indicating that preozonation can lower the degree of mutagenicity. Furthermore, the mutagenicity of the prepared humic acid samples gradually decreased after the advanced treatment process. However, when chlorine was added later to these samples, the mutagenicity increased again. This research shows that the use of O3/GAC processes to treat water can successfully lower mutagenicity, indicating a great potential for applications in the treatment of drinking water.     

Species of Trace Metals,Organic Residues and Humic Substances in Sediments From the Taiwan Erhjin River and Coastal Areas

Abstract

Total organic carbon, humic substances, and the species of trace metals (including Cu, Zn, Pb, Cd, Cr, Mn and Fe) in six and seven phases, such as bioexchangeable (P1), skeletal (carbonates, P2), easily reducible (Fe and Mn oxides, P3), moderately reducible (crystalline Mn oxides, P4), organic matters with sulphides (P5), and detritus with minerals (P6) as well as organic with humic substances (PB4) and organic residues (PB6), were analyzed in sediments from the Taiwan Erhjin coastal (including river and estuarine) area, where places we found the copper pollution. Results indicate that higher percentages of P1 and P2 for copper, zinc, lead, cadmium and manganese in samples collected in March and September of 1990 were much higher than those in P3-P6. High percentages of chromium and iron in samples respectively collected in March and September of 1990 were found in P6. for the seven phase analysis, higher percentages of copper species in PB4 and PB6 as well as iron species in PB7 were observed. On the other hand, purified humic acid with the high contents of manganese and iron in humic acid as well as purified fulvic acids were generally found at the upstream stations; and low values at coastal stations. However, extremely high copper (as high as 1750μg g^?1, dry weight in fulvic acid and 820μg g^?1 in humic acid) and lead (821μg g^?1 in humic acid) concentrations with relatively high manganese and iron concentrations were observed in humic substances from the station near the copper recycling area. Comparing the results obtained from the Antarctic Ocean sediments with those from the Taiwan Erhjin Chi coastal sediments, the human impacts on the latter are evaluated.     

Forward

Abstract

Three collectives of substances - plastics, plant nutrients, biotoxins - are candidates for monitoring programmes that could keep track of the quality of ocean waters for vital life processes. All three are not subject to systematic surveillance at present. They are each characterized by long residence times in the marine environment, by increasing influx, and by growing evidence of their deleterious impacts on living systems.