Ökonomisch-organisatorische Betrachtung der Klärschlammverwertung: Kosten — Nutzen — Ausstiegsszenarien

Goal and Scope

The controversial issue of disposing municipal sewage sludge on arable farmland and growing demand on derived fuels could result in a total or partial abandoning of sludge recycling as fertiliser. Alternative disposal strategies like incineration will cause complex changes. A material flow management framework is used to determine the economic-organisational consequences for public authorities, farmers, rural contractors, disposal firms, and population in Schleswig-Holstein.

Methods and Focus

The study is based upon network analysis, analysis of agricultural and wastewater statistics and interviews. After structuring the disposal process, transaction are used to derive costs of different disposal strategies. The purification technique of sewage plant and application of metal salts for precipitation affect the fertilising quality of sludge. Therefore, all plants are classified into 4 different technical groups with decreasing fertilising effect. Now, the amount of sludge and corresponding fertilising benefit is calculated both state wide and for typical farms. Finally costs of different disposal strategies are derived.

Results

Referring to sewage plants sludge disposal in Schleswig-Holstein is characterised by a local structure since less than 10% of all 841 sewage plants produce almost the entire sludge where as many small plants especially in rural areas produce only little amounts. Usually enriched with lime, dewatered sludge fulfilling legal limits is used as organic fertilizer. The number of transactions indicates the costs.

Discussion

To reduce transaction costs, disposal firms try to offer high quantities of sludge to a limited number of farmers. Due to purification technique, the fertilising effect of half the amount of total sludge is reduced. Compared to the total demand on phosphorous, sludge can only substitute up to 4% of phosphorous. Farmers can substitute up to 50% of mineral fertiliser and increase marginal income per hektare. Although changing disposal strategy to incineration would double economic costs, fee for wastewater would remain almost constant.

Conclusions

Small wastewater plants, farmers and rural contractors would be particularly affected by ceasing sludge disposal. Small wastewater plants would have to invest in dewatering equipment, rural contractors would lose an important market segment and farmers (only a small percentage of all farmers uses sludge) would lose additional income. Changing waste management from sludge disposal with many involved parties to e.g. incineration would considerably reduce transaction costs for authorities. In case of partly changing waste management strategy, whereas sludge of small plants could be recycled, the authorities would still have to plan and control the disposal process even for small quantities of sludge. Transaction costs do not decrease proportionally to the decreasing amount of sewage sludge.

Perspectives

Quality management systems initiated by disposal firms should increase the acceptance and prevent a ban of sludge recycling. Nevertheless, the waste market develops from material to energetic use of waste. Significant resources will be lost without a phosphorous recovering from sludge as well as from other organic waste.     

城市污水处理厂污泥处理处置的政策分析

简要介绍了城市污水处理厂污泥处理处置技术，提出污泥产业发展政策的建议，指出土地利用是符合我国国情的污泥处置的方向之一：污泥处理技术主要有减量化、浓缩、脱水、消化、堆肥等；污泥处置技术主要有焚烧、填埋、土地利用、建材利用等。污泥处理处置应按照减量化、稳定化、无害化原则，鼓励污泥资源化综合利用。合理确定污水处理厂污泥处理处置设施的布局和设计规模；鼓励对污泥处理处置给与税、费优惠政策，明确将污泥处理处置的运营费用列入污水排污收费范围，建立科学的价格补偿机制；政府在污泥产业发展中起着较为重要的作用，主要体现为服务与监督，包括承诺、保障和协调三个方面。     

城市污泥不同处理处置方式的成本和效益分析--以北京市为例

以北京市为例,估算不同电价及运输距离下填埋、焚烧及堆肥等方式的城市污泥处理处置成本,在此基础上讨论各种处理处置方案的前景,展望北京市污泥处理处置出路。污泥填埋在一定时期内还将是主要处理处置方式,但所占比例将逐渐下降;堆肥是经济上较为可行的处理处置方式,适合大力推广;随着经济实力与技术水平提高,焚烧法可以适用于个别特殊地点。同时,分析了政府补贴对污泥处理处置效益的影响。     

新型调理剂CTB-2污泥堆肥的氧气时空变化特征研究

采用新型CTB-2调理剂与城市污泥进行堆肥,研究了堆肥过程中氧气、温度的时空变化特征。结果表明,m（CTB-2调理剂）：m（污泥）=1：2能够有效降低污泥容重,改善堆体结构;堆体能够快速升温至高温期并持续7d以上,最终完成无害化;采用该比例的调理剂能够保证堆体的通风供氧,使堆体各层通风后的氧气体积分数都恢复至19％以上,最低氧气体积分数维持在数17％以上;堆肥过程中堆体的氧气体积分数、耗氧速率和温度都具有明显的层次效应,堆体耗氧速率呈先升高后降低的趋势,堆体通风后的氧气和最低氧气体积分数均随着堆肥的进行而增加。     

可控湿法氧化聚沉工艺对城市污泥中重金属的稳定化影响

采集了长沙市污水厂的剩余污泥（S1）和湿法氧化聚沉工艺处理的深度脱水污泥（S2）,对比分析了处理前后污泥的形貌变化及重金属Zn、Cu、Pb、Cd、Hg和As的形态分布,初步探讨了重金属稳定化机理,对脱水污泥中重金属Zn、Cu、Pb、Cd、Hg和As进行了稳定性评估.结果表明,脱水污泥中重金属的总量均低于我国污泥农用标准中的酸性限值,符合B级污泥泥质要求.处理后,污泥中Zn、Cu、Pb、Cd、Hg和As主要以硫化物有机结合态和残渣态（稳定态）存在,不稳定态在不同程度上向稳定态发生了转变,Cu、Hg的增幅最大,达21.1%.S2中重金属的生物可利用性较S1都有显著的降低,平均降幅达73.1%,S2中重金属的生物可利用性顺序为：Zn〉Pb〉Cu〉Cd〉As〉Hg.污泥经过湿法氧化聚沉工艺处理后,污泥中重金属Zn、Cu、Pb、Cd、Hg和As得到了明显的稳定化,为污泥后续资源化、安全化提供了科学依据.     

Co-pyrolysis of sewage sludge and biomass for stabilizing heavy metals and reducing biochar toxicity: A review

The huge amounts of sewage sludge produced by municipal wastewater treatment plants induce major environmental and economical issues, calling for advanced disposal methods. Traditional methods for sewage sludge disposal increase greenhouse gas emissions and pollution. Moreover, biochar created from sewage sludge often cannot be used directly in soil applications due to elevated levels of heavy metals and other toxic compounds, which alter soil biota and earthworms. This has limited the application of sewage sludge-derived biochar as a fertilizer. Here, we review biomass and sewage sludge co-pyrolysis with a focus on the stabilization of heavy metals and toxicity reduction of the sludge-derived biochar. We observed that co-pyrolyzing sewage sludge with biomass materials reduced heavy metal concentrations and decreased the environmental risk of sludge-derived biochar by up to 93%. Biochar produced from sewage sludge and biomass co-pyrolysis could enhance the reproduction stimulation of soil biota by 20‒98%. Heavy metals immobilization and transformation are controlled by the co-feed material mixing ratio, pyrolysis temperature, and pyrolysis atmosphere.

     

Implikationen der landwirtschaftlichen Klärschlammverwertung Status quo und Perspektiven

Goal and Scope

At all times animal as well as human excrements have been used as organic fertilizers. Disposing of municipal sewage sludge on arable farmland means saving mineral fertilizer to conserve the exhaustible resource phosphorus; one can consider this kind of recycling management as a contribution to a sustainable regional development. However, the use of sludge implies a significant release of pollutants. Hence, in Germany as well as internationally, this is a controversial issue and therefore it needs to be re-evaluated under consideration of regional circumstances.

Methods

A material flow management framework is used to first analyse toxic, fertilizing and legal aspects of the ‘sludge metabolism’ in Schleswig-Holstein, including involved participants. Then, the treatment of waste water as well as potential and actual recycling of domestic sewage sludge are regionally compared. The study is based on a survey of the municipal waste water treatment plants which serve more than 10.000 people including population equivalence; these plants cover about 94% of the sewage sludge in Schleswig-Holstein.

Results and Conclusions

After taking the phosphorus of manure into account, the modelled potentials of recycling on the scale of districts do not correspond with the actual use of sludge in agriculture. The disposal firms recycle the sludge where they can get the highest profit. By minimizing transaction costs, lager recycling distances can be compensated. The potential of phosphorus recycling is limited. The calculated state-wide amount is not more than 10% of the total phosphorus demand of the arable land, so the benefit is less important for the national economy. On the other hand, there is a significant discharge of pollutants mainly into the soil, where apart from copper and cadmium, the charge through sewage sludge is higher than through mineral fertilizer and manure. In addition, the risk of pollutants with endocrine disrupters is difficult to estimate.

Outlook

In respect of the net ecological effects, thermal utilization of sewage sludge, e.g. in clinker works, coal-fired power stations or waste incineration plants, combined with previous or additional phosphorus recovery from cinder, meets the criteria of sustainable material flows more than its use on arable land. Even though these disposal options are still more expensive, law induced adjustment of the waste market and more strict land application regulations will reduce their price differences. This will make a middle-term change from the agricultural use to a thermal recycling of sewage sludge possible to avoid soil impacts and fulfil the requirements of a sustainable development.     

Inactivation and risk control of pathogenic microorganisms in municipal sludge treatment: A review

• Diversity and detection methods of pathogenic microorganisms in sludge. • Control performance of sludge treatment processes on pathogenic microorganisms. • Risk of pathogen exposure in sludge treatment and land application. The rapid global spread of coronavirus disease 2019 (COVID-19) has promoted concern over human pathogens and their significant threats to public health security. The monitoring and control of human pathogens in public sanitation and health facilities are of great importance. Excessive sludge is an inevitable byproduct of sewage that contains human and animal feces in wastewater treatment plants (WWTPs). It is an important sink of different pollutants and pathogens, and the proper treatment and disposal of sludge are important to minimize potential risks to the environment and public health. However, there is a lack of comprehensive analysis of the diversity, exposure risks, assessment methods and inactivation techniques of pathogenic microorganisms in sludge. Based on this consideration, this review summarizes the control performance of pathogenic microorganisms such as enterovirus, Salmonella spp., and Escherichia coli by different sludge treatment technologies, including composting, anaerobic digestion, aerobic digestion, and microwave irradiation, and the mechanisms of pathogenic microorganism inactivation in sludge treatment processes are discussed. Additionally, this study reviews the diversity, detection methods, and exposure risks of pathogenic microorganisms in sludge. This review advances the quantitative assessment of pathogenic microorganism risks involved in sludge reuse and is practically valuable to optimize the treatment and disposal of sludge for pathogenic microorganism control.     

污水厂污泥制轻质陶粒研究现状及应用前景

作为污水处理厂的副产物，污泥必须进行适当的处理。在介绍了国内外污水厂污泥制轻质陶粒的研究现状的基础上，从陶粒制备工艺、技术可行性、经济效益和环境效益等方面探讨了污水厂污泥制轻质陶粒的应用前景。     

生化-物化-生态组合工艺用于离散型住宅小区污水处理与中水回用

以武汉市东西湖区园艺花城小区(3期)污水深度处理和中水回用系统建设为例,介绍和推广一套具有较强实用性的生活污水生化—物化—生态组合处理工艺。该项工艺特别适用于氮含量偏高情况下的离散型住宅小区生活污水深度处理与回用,具有占地省,处理效果稳定,易与周边环境协调等诸多优势。采用组合工艺,可使小区污水经处理后实现达标排放,中水处理系统的出水水质满足《城市污水再生利用(城市杂用水和景观环境用水)水质标准》;系统运行能耗低,污水处理和中水制水的总成本仅为0．69元/m~3。     

青岛城市污水厂污泥有机质、养分及重金属含量

对青岛市4个典型城市污水厂脱水污泥中有机质、养分及重金属指标进行了调查研究,结果表明,所调查的青岛市4个典型城市污水厂污泥中的有机质平均含量为48.58%,总氮、总磷、总钾平均含量分别为36 437.76 mg/kg、12 590.13 mg/kg2、791.55 mg/kg;青岛市4个典型城市污水厂脱水污泥中的重金属...     

Thermische Schlammkonditionierung nach dem Porteous-Verfahren

In Nuremberg (Germany), each year about 25,000 tons (dry matter) of sewage sludge are obtained as by-product of waste water treatment. The digested sludge consists of 96% water. Until 1992 it was thermally stabilized using the Porteous procedure: the sludge was heated in an autoclave up to a temperature of 180–200 °C at a pressure of 28 bar. After pressure reduction and moving to a thickener, a substantial part of the liquid could be removed. After running through a chamber filter, the sludge contained only about 50% dry matter. This treatment does not only remove water; organic matter is also degraded or evaporated. Between November 1991 and May 1992, the sludge was analyzed four times before and after the drying process and examined for heavy metals (Pb, Cd, Cr, Cu, Ni, Hg, Zn), polychlorinated biphenyls (PCB) and PCDD/F. The concentration of heavy metals and PCB (related to dry matter) increased by a faktor of 1.3 after the drying process. This effect may be explained by the decrease of organic matter during drying. In the case of PCDD/F, the ITQ increased by a factor of 3.2, for some congeners even by a factor of 8. The only explanation can be that during thermal conditioning PCDD/F is formed by precursors as chlorophenols. This formation is probably catalyzed by metals as copper or nickel and sped up by the higher temperatures.     

Effect of lime on speciation of heavy metals during composting of water hyacinth

Composting is attractive and inexpensive method for treatment and biomass disposal of water hyacinth. However, the major disadvantage of water hyacinth composting is the high content of heavy metals in the final compost. Addition of lime sludge significantly reduced most bioavailable fractions (exchangeable and carbonate) of heavy metals. Studies were carried on composting of water hyacinth (Eichhornia crassipes) with cattle manure and sawdust (6:3:1 ratio) and effects of addition of lime (1%, 2% and 3%) on heavy metal speciation were evaluated during 30 days of composting period. The Tessier sequential extraction method was employed to investigate the changes in speciation of heavy metals such as Zinc (Zn), Copper (Cu), Manganese (Mn), Iron (Fe), Lead (Pb), Nickel (Ni), Cadmium (Cd) and Chromium (Cr) during water hyacinth composting. Effects of physicochemical parameters such as temperature, pH and organic matter on speciation of heavy metals were also studied during the process. Results showed that, the total metal content was increased during the composting process. The higher reduction in bioavailability factor (BF) of Cu, Fe, Ni, Cd and Cr was observed in lime 2 treatment about 62.1%, 64.4%, 71.9%, 62.1% and 58.9% respectively; however higher reduction in BF of Zn and Pb was observed in lime 1 treatment during the composting process. Reducible and oxidizable fractions of Ni, Pb and Cd were not observed during the process. Addition of lime was very effective for reduction of bioavailability of heavy metals during composting of water hyacinth with cattle manure and sawdust.     

制革废水处理系统各级出水的生态毒性评价

采用生态毒理学常用的大型溞（Daphnia magna）和活性污泥（activated sludge）作为试验系统,对制革废水处理系统各个环节出水进行毒性试验,以评价其处理效果。按照OECD标准试验方法,选取本实验室繁殖的大型溞（溞龄小于24 h）,和采自以处理生活污水为主的污水处理厂活性污泥,分别使用重铬酸钾和3,5-二氯酚作为参比物验证大型溞和活性污泥的毒性敏感性。以大型溞活动抑制和活性污泥呼吸抑制作为毒性终点,利用48 h静态试验和3 h曝气试验分别评价水样对于大型溞活动和活性污泥呼吸作用的急性毒性效应。统计各试验组大型溞的活动情况和活性污泥的呼吸速率,分别将其与空白对照组进行比较,计算大型溞的活动抑制率和活性污泥的呼吸抑制率,采用Bliss法统计制革废水处理系统各个环节出水对大型溞和活性污泥的半数抑制浓度（EC50）。结果表明：制革废水依次经过厌氧脱硫反应器、脱色厌氧反应器、微曝气反应器和厌氧氨氧化反应器的生物处理系统处理,其出水对大型溞和活性污泥的急性毒性已大为降低。进水、厌氧脱硫反应器出水、脱色厌氧反应器出水、微曝气反应器出水和厌氧氨氧化反应器出水对大型溞活动抑制试验的48 h-EC50分别为41.3%、32.2%、48.0%、91.2%和无抑制作用;活性污泥呼吸抑制试验3 h-EC50则分别为178.2%、101.5%、689.7%、184.6%和无抑制作用。总体上毒性呈现逐渐降低的趋势,而且大型溞比活性污泥更为灵敏。大型溞和活性污泥的生态毒性结果与化学分析的结果相互补充,可为制革废水处理提供预警和效果评价提供科学依据。     

污泥处理热干燥工艺的研究进展

介绍了国外污泥热干燥工艺的现状和干燥设备的类型,阐述了热干燥方法,包括对撞流干燥、过热蒸汽干燥、燃气红外辐射干燥、间壁式热干燥和流化干燥等,及其在污泥干燥中的应用原理和发展。并分析了污泥干燥处理技术综合利用的几种途径和发展趋势,认为污泥热干燥技术拓展了污泥的处置手段,为污泥的安全、可靠利用与处理提供了保障。     

A road-map for energy-neutral wastewater treatment plants of the future based on compact technologies (including MBBR)

In the paper concepts for wastewater treatment of the future are discussed by the use of a) one flow diagram based on established, compact, proven technologies (i.e. nitrification/denitrification for N-removal in the mainstream) and b) one flow diagram based on emerging, compact technologies (i.e. de-ammonification in the main stream).The latter (b) will give an energy-neutral wastewater treatment plant, while this cannot be guaranteed for the first one (a). The example flow diagrams show plant concepts that a) minimize energy consumption by using compact biological and physical/chemical processes combined in an optimal way, for instance by using moving bed biofilm reactor (MBBR) processes for biodegradation and high-rate particle separation processes, and de-ammonification processes for N-removal and b)maximize energy (biogas) production through digestion by using wastewater treatment processes that minimize biodegradation of the sludge (prior to digestion) and pretreatment of the sludge prior to digestion by thermal hydrolysis. The treatment plant of the future should produce a water quality (for instance bathing water quality) that is sufficient for reuse of some kind (toilet flushing, urban use, irrigation etc.). The paper outlines compact water reclamation processes based on ozonation in combination with coagulation as pretreatment before ceramic membrane filtration. In the paper concepts for domestic wastewater treatment plants of the future are discussed by the use of a) one flow diagram based on established, compact, proven technologies (i.e. nitrification/denitrification for N-removal in the mainstream) and b) one flow diagram based on emerging, compact technologies (i.e. de-ammonification in the main stream).The latter (b) will give an energy-neutral wastewater treatment plant, while this cannot be guaranteed for the first one (a). The example flow diagrams show plant concepts that a) minimize energy consumption by using compact biological and physical/chemical processes combined in an optimal way, for instance by using moving bed biofilm reactor (MBBR) processes for biodegradation and high-rate particle separation processes, and de-ammonification processes for N-removal and b)maximize energy (biogas) production through digestion by using wastewater treatment processes that minimize biodegradation of the sludge (prior to digestion) and pretreatment of the sludge prior to digestion by thermal hydrolysis. The treatment plant of the future should produce a water quality (for instance bathing water quality) that is sufficient for reuse of some kind (toilet flushing, urban use, irrigation etc.). The paper outlines compact water reclamation processes based on ozonation in combination with coagulation as pretreatment before ceramic membrane filtration.     

德国的污泥利用和处置（Ⅰ）

文章论述了德国的污泥利用和处置情况,首先概述了德国的废物立法及其发展。然后比较了欧共体和德国污泥农用法规中的基本要点。随着分析了过去几十年德国的污泥产星的发展和组成,这和比较了德国汛泥和利用和处置的工艺。     

Thermal pollution abatement with simultaneous wastewater treatment plants performance improvement

The beneficial effect of high wastewater temperature on treatment plant performance and effluent quality is shown, on the basis of full scale activated sludge plant data. The wastewater temperature may be regulated by cooling water reuse. The required cooling water flowrate is analytically and graphically determined. The disposal of the reused warm water into rivers and canals may cause density stratification. From the study of the stratified stream, analytical expressions and graphic presentations of the arrested thermal wedge dimensionless length and shape are given. The graphs are presented in appropriate form for practical applications.     

污泥施用对林地土壤基本性质及酶活性的影响

以无锡卢村污水处理厂厌氧消化的脱水污泥为有机肥源,采用土培盆栽试验的方法,研究了不同用量污泥施用后土壤基本性质的变化及对土壤酶活性的影响。试验设计5种处理,污泥施用量和占土质量的比例分别为0（不施污泥的对照处理,CK）,30（3%）,60（6%）,120（12%）和240（24%）g·kg^-1。结果表明,污泥使用提高了土壤中养分元素和有机质的含量;黄棕壤中过氧化氢酶的活性平均比潮土中的高5.2%,随污泥用量的增加潮土中过氧化氢酶活性提高,而黄棕壤中的无明显变化;与对照相比,土壤脲酶活性在两种土壤上分别增加55.6%～122%（黄棕壤）和46.2%～67.5%（潮土）,且与土壤全氮、全磷、水解氮、速效磷和有机质（黄棕壤）和土壤全氮、水解氮和有机质（潮土）呈正相关;结果还显示污泥使用增加了土壤蔗糖酶活性,但不同污泥用量之间无明显差异。     

城市生活垃圾处理技术现状与管理对策

近年来,我国城市生活垃圾产生量每年以约10%的速度迅猛增长,而城市生活垃圾处理能力发展相对滞后。客观评述城市生活垃圾常用的填埋、焚烧、堆肥3种处理技术的优缺点和在国内的应用现状,并针对城市生活垃圾在收运、处理以及管理等环节中存在的突出问题,提出了明确的建议与措施：首先,完善相关法规政策,实施分类收集,加强源头控制;其次,创新管理体制,推行市场化运作机制,政府加强政策引导和监督;再次,按照＂谁污染,谁付费＂的原则,建立健全垃圾收费体系;最后,充分利用各种媒介,加大宣传力度,提高公众环保意识。同时,还探讨了城市生活垃圾处理技术发展的趋势。焚烧处理将是今后一段时期我国最有发展潜力的技术,气化熔融焚烧技术是一种高效资源化、污染物接近零排放的新型焚烧技术;生物反应器填埋技术可减少渗滤液处理量、降低垃圾处理成本,具有广阔的发展前景;堆肥技术可作为焚烧或填埋之前的预处理手段;城市生活垃圾综合处理集多种处理技术的优点于一体,在节约处理成本,提高经济效益的同时,实现了垃圾的减量化、资源化、无害化,是未来我国生活垃圾处理的优先发展方向。