Performance of a subsurface-flow constructed wetland in southern China

IntroductionTheconstructedwetlandshavebecomeaglobaltechnologyforwaterpollutioncontrolbothindevelopedanddevelopingcountries(Seidal,196 6 ,1976 ;Kickuth ,1977;Cooper,1995 ;IWA ,2 0 0 0 ) .Recentinventoriesindicatedthattherearemorethan 6 0 0 0andmorethan 10 …     

Degradation of phenol in an upflow anaerobic sludge blanket(UASB) reactor at ambient temperatureKE

A synthetic wastewater containing phenol as sole substrate was treated in a 2.8 L upflow anaerobic sludge blanket(UASB) reactor at ambient temperature. The operation conditions and phenol removal efficiency were discussed, microbial population in the UASB sludge was identified based on DNA cloning, and pathway of anaerobic phenol degradation was proposed. Phenol in wastewater was degraded in an UASB reactor at loading rate up to 18 gCOD/(L·d), With a 1:1 recycle ratio, at 26(1℃, pH 7.0-7.5. An UASB reactor was able to remove 99% of phenol up to 1226 mg/L in wastewater with 24 h of hydraulic retention time(HRT). For HRT below 24 h, phenol degradation efficiency decreased with HRT, from 95.4% at 16 h to 93.8% at 12 h. It further deteriorated to 88.5% when HRT reached 8 h. When the concentration of influent phenol of the reactor was 1260 mg/L(corresponding COD 3000 mg/L), with the HRT decreasing(from 40 h to 4 h, corresponding COD loading increasing), the biomass yields tended to increase from 0.265 to 3.08 g/(L·d). While at 12 h of HRT, the biomass yield was lower. When HRT was 12 h, the methane yield was 0.308 L/(gCOD removed), which was the highest. Throughout the study, phenol was the sole organic substrate. The effluent contained only residual phenol without any detectable intermediates, such as benzoate, 4-hydrobenzoate or volatile fatty acids(VFAs). Based on DNA cloning analysis, the sludge was composed of five groups of microorganisms. Desulfotomaculum and Clostridium were likely responsible for the conversion of phenol to benzoate, which was further degraded by Syntrophus to acetate and H2/CO2. Methanogens lastly converted acetate and H2/CO2 to methane. The role of epsilon-Proteobacteria was, however, unsure.     

Preparation and emission characteristics of ethanol-diesel fuel blends

The preparation of ethanol-diesel fuel blends and their emission characteristics were investigated. Results showed the absolute ethanol can dissolve in diesel fuel at an arbitrary ratio and a small quantity of water(0.2% ) addition can lead to the phase separation of blends. An organic additive was synthesized and it can develop the ability of resistance to water and maintain the stability of ethanol-diesel-trace amounts of water system. The emission characteristics of 10%, 20%, and 30% ethanol-diesel fuel blends, with or without additives, were compared with those of diesel fuel in a direct injection(DI) diesel engine. The experimental results indicated that the blend of ethanol with diesel fuel significantly reduced the concentrations of smoke, hydrocarbon(HC), and carbon monoxide(CO) in exhaust gas. Using 20% ethanol-diesel fuel blend with the additive of 2% of the total volume, the optimum mixing ratio was achieved, at which the bench diesel engine testing showed a significant decrease in exhaust gas. Bosch smoke number was reduced by 55%, HC emission by 70%, and CO emission by 45%, at 13 kW/1540 r/min. However, ethanol-diesel fuel blends produced a few ppm acetaldehydes and more ethanol in exhaust gas.     

城市污水再生回用于景观水体水质安全保障技术

研究了再生水回用于景观水体时可能存在的水质安全性问题,并提出了保障再生水安全回用的处理工艺。研究表明,城市污水再生水回用于景观水体时,存在着卫生学安全、毒理学安全、富营养化以及底质二次污染等危害。为了满足景观水体的水质标准,需要重点控制的水质指标有病原性微生物、有毒有害有机物、重金属、氮磷植物性营养物质、悬浮固体。以城市污水厂二级出水作为再生水原水时,推荐采用的工艺有:二级处理混凝沉淀过滤消毒、二级处理过滤活性炭吸附消毒以及二级处理膜处理消毒工艺。     

小型都市工业园环境影响评价的研究——评价要点及技术方法的选择

分析了老工业基地城市小型都市工业园的具体情况;指出了对小型都市工业园进行环境影响评价的特殊目的;阐述了小型都市工业园进行环境影响评价应重视的要点;探索了小型都市工业园环境影响评价相应的技术方法。     

防震减灾与新农村建设

在新农村的建设中．如何将防震减灾工作纳入整个村镇规划、建设与管理中,已成为重要问题之一。     

聚磷酸钙可降解纤维研究

为解决材料在环境中的降解问题,制备了聚磷酸钙纤维．研究表明其结构为无定形玻璃态,抗拉强度为１．９０ＧＰａ,弹性模量为６７．５ＧＰａ,并可发生化学降解,故可作为可降解复合材料的增强纤维     

改进的二相厌氧消化系统的特性研究

研究填充酸化反应器及其与ＵＡＳＢ甲烷化反应器组成的二相厌氧消化系统的运行特性,填充酸化反应器启动方便酸化速率高,抗水力冲击和ｐＨ波动的能力强,ＣＯＤ容积负荷达２００ｋｇ／（ｍ＾３．ｄ）,采用预调碱工艺,二相消化运行正常,可高效地处理酿酒废水,在进为ＣＯＤ浓度１０００－７０００ｍｇ／Ｌ,ＣＯＤ负荷４０ｋｇ／（ｍ＾３．ｄ）时,出料ＣＯＤ浓度小于２００ｍｇ／Ｌ对抗生素生产废水也有较好的处理效果。     

火电厂冷却池热污染治理初探

通过系统的模型试验,以色水为示踪剂模拟热水,探讨排、取水口分列式布置的三维时间连续点源如何采用工程设施转换成无限长二维面源,以利用水面热交换解决火电厂冷却池热污染的治理问题。给出了出流近区流速分布及流量沿程变化的近似计算式。此研究成果对挖掘冷却池散热潜力,增加电厂装机容量具有实用推广价值     

炉内喷钙脱硫技术及其主要影响因素简述

本文介绍国外炉内喷钙脱硫技术的最新发展,综述影响脱硫效率的各种因素.简介芬兰Tampella有限公司开发的LIFAC技术和国外有关利用吸收剂再循环等方式提高脱硫率和钙利用率的研究结果,展望了炉内喷钙脱硫技术的发展前景.