城市生活垃圾和污泥混合堆肥中氮素变化规律研究

进行了不同比例的垃圾和污泥混合的高温好氧静态堆肥小试试验,主要研究了堆肥过程中全氮、氨氮、硝态氮、水溶性氮以及有机碳等的变化.结果表明,堆肥过程中有机碳、全氮和碳氮比呈下降趋势;堆肥产品中全氮与其初始浓度成正比,初始浓度越高,结束时全氮越高;碳氮比在整个堆肥过程中变化不大;氨氮的变化显著,堆肥23 d,3种比例的混合样品(垃圾和污泥体积比分别为9∶1、5∶1和3∶1)中的氨氮分别由堆肥前的11.1、10.9、10.5 g/kg下降到1.1、2.1、3.1 g/kg;水溶性全氮和水溶性氨氮的下降趋势明显,水溶性氨氮是构成水溶性全氮的主要成分,堆肥前期温度的上升引起水溶性全氮和水溶性氨氮的迅速下降;硝态氮和水溶性硝态氮的浓度低,变化小;氮素损失主要在第3～10天的堆肥高温期,污泥量越大,氮素损失越严重,氮素损失率最高达45%.     

Solidification of tannery wastes

The high chromium concentrations in tannery-wastewater treatment-plant sludges, render them unsuitable for direct disposal. Therefore, one aims to fix the chromium of the tannery waste by adding different additive materials to cause solidification. The properties of the raw sludge were determined and subsequently, the sludge was mixed with cement and additives and left to solidify for 28 days. During the study, 28 different mixtures were prepared and their compressive strengths were determined. Standard elutriation tests were carried out with each solidified sample. Compressive strengths were obtained below the desired concrete strengths. Most of the pollutant parameters in eluate were under the required values.     

堆肥腐熟度的研究进展

评价腐熟度是有关堆肥土地安全利用最重要的问题之一。腐熟度指标可分为三类：物理学指标、化学指标及生物学指标。物理学指标易于检测,常用于描述堆肥过程所处的状态;化学指标得到了广泛研究和应用;堆肥过程是一个生物过程,腐熟度与未腐熟堆肥中植物毒性物质有关,可采用生物学方法进行评价。现在还没有一种公认的堆肥腐熟度指标。采用化学和生物指标综合评价腐熟度是目前最为常用的评价方法。     

堆肥技术及进展

堆肥技术是有机固体废弃物处理和资源化利用的一种有效手段。堆肥系统可分为条垛式、强制通风静态垛式和反应器式三大类。影响堆肥系统运行的主要操作因素有：水分、Ｃ／Ｎ比、调理剂、氧含量、温度和ｐＨ值     

Water resources issues of small island developing states

The water resources of most small island developing states (SIDS) are often very limited and require special consideration to ensure that they are developed and managed in a sustainable manner. Many small islands, typically located in the humid tropics, have no surface water resources and rely on limited groundwater resources in the form of thin freshwater lenses. The exposed location of small islands makes them particularly vulnerable to natural disasters such as cyclones, floods and droughts. Pollution from population centres and from agricultural and other activities is an increasing problem. This article provides an overview of the water resources of small islands, and the main problems and issues related to water resources. Some suggested solutions, based on practical experiences, are offered for water resource assessment and monitoring programmes, and water resource development. Water resource policy, planning and management issues are also addressed, and suggested approaches for resolving some of the major water resource problems presented.     

亚临界水技术处理厨余垃圾的比较研究

在亚临界实验条件下,以淀粉、纤维素类物质为模型化合物,H₂O₂为氧化剂,研究了厨余垃圾（大米、白菜）在亚临界水中部分氧化获取小分子有机酸的过程中处理时间、处理温度、加氧量对有机酸（甲酸、乙酸）生成的影响。以碳转化率为评价指标,确定反应最佳条件。实验结果表明：淀粉和纤维素分别在处理时间1～1.5 min,加氧量70%～100%,温度280℃;处理时间1～2 min,加氧量70%～100%,温度280～300℃条件下,生成有机酸浓度最大,达到最佳工艺条件。     

餐厨垃圾与铬污染土壤混合堆肥中铬形态的转化

进行了不同比例铬污染土壤与餐厨垃圾混合堆肥实验,分析了堆肥过程铬形态的变化、浸出液毒性以及种子发芽指数.结果表明,堆肥实验后,堆肥物料中可交换态和碳酸盐结合态的铬含量逐渐减少,最多可分别减少82.6%和72.69%,有机结合态的铬含量明显增加,最大增幅为106.58%;堆肥物料浸出液铬的浓度低于国家危险废物鉴别标准,浸...     

中国城市生活垃圾处理现状及发展建议

通过对不同发达国家城市生活垃圾处理方式的研究,发现并不是所有发达国家城市生活垃圾处理都是以焚烧方式为主,垃圾焚烧处理的比例与国家的发达程度并没有完全的对应关系,而是与国家或地区的土地资源的紧缺程度关系较大。土地资源的紧缺程度以人口密度表示,定量研究了发达国家垃圾处理方式与人口密度的关系,结合中国各省份(除特别行政区和台湾地区外)的人口密度、垃圾处理现状,对各地区的垃圾处理方式提出建议,应因地制宜地调整城市生活垃圾处理方式的应用比例,以利于更好地解决中国城市生活垃圾的处理难题。     

石灰投加与搅拌对生态厕所的灭菌效果

以发展中国家农村地区的卫生条件改善为目的,开展了简易生态厕所的粪便堆肥处理实验。在投加石灰作为抑菌剂的条件下,研究了搅拌混合对杀灭致病微生物的影响,以及使堆肥终产物达到可接受风险值所需的最佳搅拌条件。实验确定了石灰的投加量,并应用Beta-Possion模型对堆肥处置过程中致病微生物对暴露人群的健康风险进行评价,从而从健康风险控制的角度确定了最佳的搅拌次数。研究结果表明,石灰投加量约占堆肥干重1.5%,手动搅拌50次,经搅拌后放置12 h能达到可接受的风险值(3.2×10-5)。     

Physicochemical characterization of industrial effluents and their effect on fish survival

Abstract

Water samples taken from selected industrial drainages and receiving streams in and around Islamabad, Pakistan, during the summers of 1987 to 1990 showed disturbances in pH and low oxygen levels. Selected metals (Fe, Pb, Zn, Cd, Cu, Ni, Hg) were higher in all effluents than in receiving waters. Static bioassays of the undiluted industrial effluents from three sites caused 100% mortality in carp during the first 24 hrs. Fishes also suffered 30 to 60% mortality when exposed to other undiluted industrial effluents and some mortality when industrial effluents were diluted by 50%.