Soil effects due to sewage sludge application in agriculture

Field trials show that increased nutrients (mainly P) and heavy metals in soil due to agricultural use of sewage sludge have mainly to be expected when sludge is applied in too high amounts. The biological effects of heavy metals on plants are determined by their solubility which is increased by pH decrease and degradation of organic matter. Normally, it should be expected that the microbial activity in soil would increase with the application of organic matter in sewage sludge. But, also negative effects on the microflora by simultaneous enrichment of organic matter or inorganic and organic pollutants were found. The most important deleterious effects on soil microorganisms are the reduction in size of the total biomass, a reduced nitrogen fixing activity and changes in the composition of microbial populations of the soil. At what stage heavy metal toxicity to soil microorganisms or to microbial processes in soil is likely to become evident is unfortunately still uncertain. Again, the soluble fraction of heavy metals (also of organic pollutants) is a determing factor. To minimize the shown environmental risks an adequate sludge management is proposed.     

Potassium availability with application of sewage sludge,and sludge and manure composts in field experiments

An experiment was conducted to determine the plant availability of K in organic wastes. Four materials: digested sewage sludge (DSS), digested irradiated sludge (DISS), digested, irradiated and composed sludge (DICSS), and composted livestock manure (CLM) were applied to farmland for two years at rates of 10, 20, 30, and 40 mg-solids ha^–1 yr^–1. Potassium fertilizer (KCl) was added to the control treatment (CT), to which no waste was applied, and to the low-rate waste applications, to meet crop K requirement. Equal yields within different treatments were obtained for the test crops lettuce and snap beans through application of available N at the levels balanced for crop economical production. Potassium from the wastes was evaluated based on the assumption that Crop K uptake/Available K applied was equal between the CT and waste treatments. The results indicated that, in general, K applied with wastes (waste K + fertilizer K) was equally available (101±7%) to fertilizer K (KCl), except for low rate application of DISS (10 Mg ha^–1), where the availability of K was low (89±1%).     

Influence of application of sewage sludges, and sludge and manure composts on plant Ca and Mg concentration and soil extractability in field experiments

Application of organic waste influences crop uptake of Ca and Mg and soil extractability, depending on the nature of the crop and the waste. Four organic wastes: (i) digested sewage sludge (DSS), (ii) irradiated sludge (DISS), (iii) composted sludge (DICSS), and (iv) composted livestock manure (CLM) were applied for two years at rates of 10, 20, 30, and 40 Mg solid ha^-1 year^-1. Fertilizers N and K were applied to the control treatment (CT), as well as to the waste treatments to supplement crop growth across all treatments, so that these nutrients were not treatment variables. Calcium and Mg concentrations in the tissue of lettuce, bean pods and petunias in 1990 and two cuts of lettuce in 1991, and the CH₃COONH₄-extractable soil Ca and Mg were determined. Concentration of Ca and Mg in bean pods did not change to the waste application. Calcium concentration in bean pods was less than half of that in other crops. Magnesium concentration in bean pods and petunias was same, but was much lower than in lettuce. Application of DSS, in general, increased Ca concentration in the crops more than did other wastes. The extractable soil Ca was positively correlated with Ca applied with DISS (r=0.453, P<0.05). Although only a limited amount of Ca was supplied with CLM at the rate of 10 Mg solid ha^-1(40 kg Ca ha^-1), Ca concentration in petunias increased significantly, then, decreased with increased Ca application (r=0.453, P<0.05). A similar pattern with CLM was found in the extractable soil Ca. The waste application from all the sources had no influence on crop Mg concentration in 1990, possibly due to low Mg concentration in the wastes. While continuously applied DSS and DISS in 1991 linearly increased Mg concentration in both cuts of lettuce (r=0.867, P<0.01; r=0.670, P<0.01 and r=0.671, P<0.01; r=0.665, P<0.01 for first cut and second cut of lettuce with DSS and DISS application respectively), application of CLM decreased Mg concentration in first cut lettuce. The patterns of extractable soil Mg were opposite to crop Mg concentration, as the extractable soil Mg linearly increased with CLM, and decreased with the high rate of DSS application. The ability of wastes to supply N was an important factor influencing crop cations (K, Ca and Mg) uptake.     

活性污泥数学模型在污水处理中的研究进展

综述了活性污泥数学模型的发展历程以及应用现状,阐释了其在适应复杂多变的水质水量状况、实时展示模拟结果、节省人力物力投入等方面的优势,提出了建立进水组分测定统一标准、不确定性分析评估框架,以及优化模型工艺概化方式是当前主要的应用难点。将为推动活性污泥数学模型在污水处理方向的研究,实现污水处理厂智能化管理的目标提供一定的参考和借鉴意义。     

污水处理厂污泥制备生物炭及应用的研究进展

以污泥为原料制备生物炭是实现污泥资源化利用的途径之一,具有成本低、方法简单等优点。为了推动污泥制备生物炭技术的发展和应用,本文从制备方法、影响因素和应用领域等方面总结和归纳了污水处理厂污泥制备生物炭的研究现状,阐述了污泥生物炭不同制备方法及其优缺点,详细分析了不同影响因素对污泥生物炭产率、比表面积、孔径大小和孔径分布等特点的影响,总结了污泥生物炭在环境和农业领域的应用情况,提出了目前污泥制备生物炭技术存在的生物炭产率低、重金属易析出和生产批次差异等问题,并指出了今后的发展方向。     

污泥土地利用需注意的问题

污泥是城市污水处理厂不可避免的产物。随着工业的发展和城市化进程的加快,城市污泥的产量急剧增加。城市污泥中含有丰富的有机质及氮、磷等营养元素,但同时也含有种类较多含量不等的重金属、微量的有机污染物和病原物。所以将产生量巨大、成分复杂的污泥经过科学处理后,使其减量化、无害化、资源化,已成为我国乃至全世界环境界深为关注的课题之一。目前,国内外主要的污泥处置方法有填埋、焚烧和土地利用等。污泥土地利用是城市污水污泥资源化利用的一个重要技术途径,为了保证污泥土地利用更加安全有效,本文提出了污泥土地利用应注意的问题。     

挤出式污泥脱水装置在大牛地气田含醇含油污泥处理中的应用

在大牛地气田天然气开发过程中,产生大量含有甲醇、凝析油的污泥,为避免污泥污染环境,需使用专门的脱水设备处理污泥,降低污泥含水率,然后将污泥焚烧。经传统板框式脱水机、带式脱水机等脱水设备处理后的泥饼含水率在75%-85%之间,需要进行二次干化处理,而新型的挤出式污泥脱水装置处理后的泥饼含水率最低可降低到65%,无需进行二次干化处理,大大提高了污泥处理效率,同时也取得了较好的安全效益和经济效益。     

Conversion of municipal sewage sludge in supercritical water

The conversion of the organic matter of municipal sewage sludge in water under supercritical conditions (T≤750°C; P≤30 MPa) was studied. According to mass-spectrometric data, CO₂, H₂, CH₄, and NH₃ were predominant among volatile conversion products. The kinetic parameters of conversion were determined. It was found that the rate of the process increased with temperature and mainly depended on the interaction of water molecules with sewage sludge carbon T > 600°C.     

重金属市政污泥固化稳定化技术研究

对某污水处理站产生的污泥进行固化稳定化处理,测定其无侧限抗压强度、水稳定性、重金属浸出毒性、渗透性等指标。实验表明,处理后污泥无侧限抗压强度可达0.2 MPa,水稳定性无明显变化,重金属浸出浓度低于毒性鉴别标准值,渗透性满足填埋指标要求。     

城市污水厂污泥稳定化技术研究进展

基于城市污水厂污泥处理处置的现状,综述了污泥稳定化的作用机理与国内外当前污泥稳定化技术具有代表性的一些研究成果,主要包括:污泥消化技术、污泥堆肥化技术、污泥固化稳定化技术、污泥湿式氧化技术、污泥等离子体处理技术、氯氧化技术。并对污泥稳定化技术的发展前景提出了自己的见解,以期促进污泥稳定化技术发展与工业化应用。     

污泥质活性炭吸附剂的制备和吸附性能研究进展

介绍了目前污泥质活性炭吸附剂制备方法及在治污方面的应用进展。阐述了污泥直接干化法、传统活性炭活化碳化法和微波活化碳化法等制备方法的研究现状,指出向污泥中添加金属氧化物、聚合物以及相应的辅料,可改变污泥碳的结构,提高吸附去污效能。初步探讨了污泥质活性炭吸附剂的除污机制和朗格缪尔及弗兰德利希模型的应用研究。     

我国应用生物技术资源化利用城市剩余污泥的研究进展

对我国近年来应用生物技术对城市剩余污泥进行厌氧发酵产沼气、厌氧发酵产氢气、厌氧发酵产生化产品以及污泥堆肥农用等四个领域的研究现状和进展进行了综述。分析发现,厌氧发酵产沼气和堆肥技术比较成熟,得到了比较广泛的应用,而污泥产氢气还处于试验室和中试研究阶段,污泥产生化产品和微生物燃料电池则刚处于起步阶段,具有很大的发展前景。     

城市污水污泥脱水的最新研究进展

随着"十一五"污水处理厂建设数量的大幅增加,我国污泥产量也随之急剧增长,污泥的处理处置已成为制约社会经济发展的重要问题。综述了近十年国内外有关污水污泥脱水的最新研究进展,提出了存在的问题,并对未来研究方向进行了展望。     

Modelling the effects of imperfect mixing on the performance of anaerobic reactors for sewage sludge treatment

An approach to the modelling of suspended-growth anaerobic digestion systems based on the assumption of an incompletely mixed reactor is presented. The mathematical model developed describes the dynamic behaviour of anaerobic sludge digesters under non-ideal mixing conditions. The microbial kinetic model for the anaerobic digestion of waste-activated sludge distinguishes the processes of death and lysis of activated sludge cells, hydrolysis of particulate material, fermentation of soluble substrates, volatile fatty acids utilisation and methane formation. The interaction of two microbial groups is considered, i.e. acid-formers and methanogens. Their growth is assumed to depend on Monod kinetics for the substrates. Death and lysis, hydrolysis and biomass decay are described by first order reactions. The biokinetic expressions were linked to a simple mixing model which considered the reactor volume split into two sections: the flow-through and the retention regions. The transfer of material between regions was assumed to be limited. Deviations from an ideal completely mixed regime were represented by changing the relative volume of the flow-through region (α) and the turnover time of material in the vessel (τ). The dynamic model described the effects of the retention time and reactants' distribution, resulting from the mixing condition, on process performance. Computer simulations under different conditions showed a considerable decline in methane production and treatment efficiency due to incomplete mixing. The COD removal efficiency increased by extending the retention time and the degree of mixing. The evaluation of the impact of the mixing parameters showed that α has a far more significant effect on the performance of anaerobic digestion than τ does. Nevertheless, both are important and the overall efficiency is a complex function of both parameters. The results obtained confirm and emphasise the importance of considering mixing when simulating anaerobic digestion, calculating process conversion efficiency, and during anaerobic reactor design. © 1998 SCI.     

Extraction and characterisation of extracellular polymers in digested sewage sludge

Five different bacterial extracellular polymer extraction methods were compared on digested sewage sludge. A washing step was necessary to remove and eliminate the slime from the sludge sample, in order to distinguish it from the material more tightly bound to the sludge solids. An ion-exchange resin method was the most effective and least disruptive of all treatments tested, based on the relatively high extracellular polymer yield and the small amount of cell disruption demonstrated by the fractionation and characterisation of the extracted material. The extracellular polymer extracted contained protein and polysaccharide in a ratio of approximately 3:1, and contributed a relatively small proportion of the total solids in digested sludge. This was comparatively less than is extracted in activated sludge. The ion-exchange resin method yielded 1% by weight of polysaccharide and 3% of protein, whereas ethanol-insoluble material accounted for 3.5% of the solids in digested sludge.     

高效咪唑啉污水缓蚀剂的合成及现场应用

以松香、蓖麻油与二乙烯三胺在一定条件下合成咪唑啉类MB缓蚀剂，由于松香型咪唑啉和蓖麻油型咪唑啉，化学结构和相对分子质量各异。两者相互补充，能够在金属表面形成致密的保护膜。近几年来，使用MB缓蚀剂处理胜利东辛采油厂污水，使得腐蚀速率控制在较低水平，通过室内评价与现场应用实验，证明其有高效的缓蚀作用。     

城市污水厂污泥稳定化技术研究进展

基于城市污水厂污泥处理处置的现状,综述了污泥稳定化的作用机理与国内外当前污泥稳定化技术具有代表性的一些研究成果,主要包括:污泥消化技术、污泥堆肥化技术、污泥固化稳定化技术、污泥湿式氧化技术、污泥等离子体处理技术、氯氧化技术。并对污泥稳定化技术的发展前景提出了自己的见解,以期促进污泥稳定化技术发展与工业化应用。     

污水厂污泥中类二噁英类物质污染水平的研究进展

污水厂污泥的农业资源化利用是污泥处置的重要方法之一,但污泥中所含有毒有害的类二噁英类物质会制约污泥的农业利用.本文综述了污水厂污泥中类二口恶英类物质的污染水平和特点,为进一步制定和完善我国农用污泥中类二口恶英类物质控制标准提供科学的依据.     

Application of sewage sludge in the manufacturing of ceramic tile bodies

The substitution of clayey raw materials urban sewage sludge in the production of traditional ceramics could give place to a cost saving due to the utilisation of wastes as secondary raw material. At the same time, it can help to solve the environmental problems associated to such wastes. This research shows the results of the substitution of clay for sewage sludge in different proportions in a ceramic body. The sludge characterisation has been carried out by an analytical protocol. After that, the most suitable products were selected regarding to the chemical composition and the technological characterisation of the resulting ceramic material.     

热解技术资源化处理城市污泥的研究进展

热解技术作为一种新兴热化学处理技术,能将废弃物转化为稳定多用途可利用能源,二次污染小,近年来在污泥处理领域得到国内外的关注。本文介绍了污泥热解技术的基本原理,并按照热解目的产物的形态进行分类,分别从固、液、气相目的产物3个方面对相关污泥热解技术特点和产物特性进行了综述,介绍了国内外理论研究的发展概况,并对目前主要工程应用进展及相关联用工艺和新型工艺发展趋势进行讨论,同时探讨了热解技术在城市污泥处理领域下一步可能的发展方向。