污泥深度脱水干化/焚烧技术分析及其经济性评估

全面分析了我国污泥的产生现状,对比分析了目前主要的污泥干化处理处置技术。污泥干化处理技术能够有效对污泥进行深度脱水,并且不改变污泥热值,是一种具有前景的污泥处理工艺。详细介绍了该技术的收集、预处理、深度干化及返混、焚烧发电等步骤,分析了其主要污染物及控制技术。借助示范工程实例中污泥深度脱水干化/焚烧一体化技术工艺的运行状况,对污泥深度脱水干化/焚烧技术进行经济性评估。     

城市污泥太阳能光热干化技术研究进展

污泥干化是城市污泥无害化处置和资源化利用的前提和关键工序,需要消耗大量能源。将太阳能应用于城市污泥干化,可大幅度减少污泥干化过程对常规能源的依赖,经济高效地实现污泥的稳定化、减量化及资源化。对国内外城市污泥的处理处置和太阳能污泥干化技术的研究现状进行综述。     

专利文摘

一种焚烧及污泥干化工艺该专利涉及一种焚烧及污泥干化工艺。包括以下步骤:1)将固体可燃废料送入热解焚烧装置,通过干馏、燃烧形成高温烟气;2)将得到的高温烟气送至装有湿污泥的回转窑内提供热源,使湿污泥在回转窑内充分干化、热解和燃烧,得到干污泥和热解后的废气;3)将热解后的废气送至燃烧室进一步提温灼烧后,送至尾气处理装置处理后     

污泥炭调理剂用于污泥脱水实验的探究

污泥的处理是"世界难题",污泥处理处置现状与我国污水处理差距甚大,远远落后发达国家,与我国的大国地位及生态文明建设不相符。污泥处理主要是进行减量化、稳定化、无害化和资源化。无论怎么处理,污泥脱水都是必须的处理过程。污泥中的水分主要以孔隙水和毛细水两种形态存在,主要为间隙水、毛细管结合水,表面吸附水和内部水。污泥填埋场的污泥经过多年的沉积,污泥干化严重,含水率低,流动性差,不能直接进行板框压滤,需要添加污泥渗滤液增加污泥的含水率和流动性,通过添加污泥炭调理剂,污泥炭调理剂能够作为骨架支撑,提高了污泥的透水性,影响污泥比阻。污泥炭充分研磨后,比表面积增大、质轻,具有较强的吸附能力,能与吸附质的化学键或离子发生结合,从而产生吸附作用。     

一套负压移动式污泥干化处理设备

该专利公开了一套负压移动式污泥干化处理设备。该处理设备包括安装在移动式方舱上后部的污泥抽取单元、清洗箱、脱水单元、输送单元、加药单元、密封包装单元及安装在移动式方舱上前部的发电机及其电控柜一和电控柜二。移动式方舱上的后部为密闭舱，密闭舱内还置有净化通风单元、控制显示单元和消毒单元。净化通风单元可将移动式方舱内的空气过滤后排出并保持移动式方舱内为负压，控制显示单元检测移动式方舱内的负压值并进行报警，消毒单元可杀灭移动式方舱内的病毒。该发明在切断了污泥处理过程中所产生的各种病毒向外传播与蔓延渠道的同时，也可避免系统在移动过程中系统空间的污染空气及所带病毒向外界泄漏传播。     

城镇污泥脱水综合处置方法

利用生物沥浸浓缩技术处理污泥改变其特性,导致污泥的pH值下降3-6,菌剂不含有害物质推广隔膜滤板压榨工艺提高污泥的水解效率和挥发性有机酸的生成率,实现污泥内含物的快速释放隔膜滤板压榨压力设置为3．5MPa,压榨后的泥饼含水率降为50％以下。污水的规范处置可灌溉农田和再循环利用,泥饼干化可储存为有机肥料,可以焚烧发电转化为能源利用,为社会带来极大效益的同时,对治理环境具有重要的意义,     

高含水含油污泥水热处理技术研究进展

高含水含油污泥含有大量的自由水、结合水和乳化水，其脱水干化是后续处理处置的瓶颈。近年来水热处理技术被引入石油石化工业用于高含水含油污泥的脱水干化和回收油。本文介绍了高含水含油污泥的来源、成分、分类、特点和处理难点，概述了高含水含油污泥调质脱稳技术现状，总结了高含水含油污泥水热处理技术取得的主要进展，分析了水热处理技术的处理机理、技术特点、优点和缺点，并展望了该技术的发展方向。     

日本污泥脱水凝聚剂发展概况

活性污泥法处理工业废水,将生成大量的剩余污泥,其量约为废水处理量的1—2%,且含水率相当高,约为99%以上。如果剩余污泥任意堆放或者处理不妥,就会产生臭味污染大气以及随水流失而污染水体,造成二次公害。在我国剩余污泥处理工作,如污泥脱水、焚烧、脱臭、除尘以及污泥的利用与处置等刚刚开展。活性污泥脱水是去除污泥中大量水     

焚烧温度对电镀污泥后续处理影响研究

在传统的电镀污泥回收有价金属工艺基础上,提出了焚烧预处理新技术,成功降低了电镀污泥的含水率,使其体积及重量都大幅度的减少,并同时提高了焚烧渣的重金属含量.当焚烧温度适宜时,焚烧对电镀污泥的酸浸过程的影响很小,重金属的浸出率仍保持在较高水平.     

电镀污泥资源化利用的研究进展

阐述了电镀污泥的特点及危害,对近年来国内外电镀污泥资源化利用方法的研究进展进行了综述,包括有价金属的回收技术、材料化技术等。系统地总结了各种资源化方法的优势及存在的问题,并对主要资源化技术的应用前景进行了分析。     

Study on optimal energy efficiency of a sludge drying-incineration combined system

Thermal drying is a frequently used technology to further remove the water in dewatered sludge. However, it is an expensive solution due to its highly energy consumption. The combination of sludge drying and incineration system, in which, the energy generated from sludge incineration is reused to sludge drying, can largely save the energy consumption of sludge treatment facilities. A bench-scale paddle sludge dryer was built to study the drying characteristics of sludge. Results show that, a significant fluctuation of sludge drying rate and stirring power emerges at the moisture content of 55–65 %. An energy model was established based on a sludge drying and incineration project. The most reasonable dryness of sludge outlet from sludge dryer and input to sludge incinerator was analyzed, in the purpose of achieving optimal energy efficiency. The mono-incineration of dry sludge can be achieved at 850 °C combustion temperature, when sludge lower heating value (LHV) is about 11213 kJ/kg and moisture content is about 60 % w/w. The effect of operation conditions, including sludge moisture content, LHV, and operation load were analyzed based on the energy model. This energy model could be applied for the improvement of energy efficiency of sludge drying and incineration combined system.     

Drying characteristics of sewage sludge using vacuum evaporation and frying

This study was performed to investigate the possibility of utilizing sewage sludge as a fuel. The drying characteristics of sewage sludge were examined by using vacuum evaporation and fry-drying technology in a batch-type rotary evaporator. In addition, the optimal drying conditions of sludge in the vacuum evaporator were investigated in terms of the vacuum pressure, temperature, and oil dosage ratio, etc. Experimental results showed that the moisture content in the sludge decreased with increases in oil/sewage sludge ratio and temperature. Dried sludge fuel (SDF) product could be obtained with on average less than 5% moisture content and a lower heating value of more than 4000 kcal/kg. Considering energy efficiency, we suggest that the optimal operating condition for drying sludge is ?450 mmHg of vacuum, a temperature of 100°C, a drying time of 90 min, and a sludge/oil ratio of 1:1. The SDF product was shaped as granules and fluff-type particles. Evaluated from the perspective of the energy balance and economic considerations, this sludge drying system with vacuum fry drying could be used for effective sludge treatment and the production of SDF.     

Novel fry-drying method for the treatment of sewage sludge

The purpose of this study is to introduce an efficient drying method named “fry-drying technology” for the treatment of sewage sludge. The basic principle of this method lies in the rapid escape of moisture from sludge material through its pores into the oil medium driven by the strong pressure gradient formed between sludge and oil media. This beneficial pressure distribution for moisture transfer can be established by the subtle combination of the difference of physical properties of specific heat and boiling temperature between water and oil. In order to determine the physical characteristics of this fry-drying technology, a series of experiments were performed in which important parameters, such as heating oil temperature, drying time, oil type, and sludge size, were varied. Numerical calculations using a single solid spherical particle model without any porosity were used to resolve the particle size effect associated with sludge drying.     

Energy recovery from sewage sludge by means of fluidised bed gasification

Because of its potential harmful impact on the environment, disposal of sewage sludge is becoming a major problem all over the world. Today the available disposal measures are at the crossroads. One alternative would be to continue its usage as fertiliser or to abandon it. Due to the discussions about soil contamination caused by sewage sludge, some countries have already prohibited its application in agriculture. In these countries, thermal treatment is now presenting the most common alternative. This report describes two suitable methods to directly convert sewage sludge into useful energy on-site at the wastewater treatment plant. Both processes consist mainly of four devices: dewatering and drying of the sewage sludge, gasification by means of fluidised bed technology (followed by a gas cleaning step) and production of useful energy via CHP units as the final step. The process described first (ETVS-Process) is using a high pressure technique for the initial dewatering and a fluidised bed technology utilising waste heat from the overall process for drying. In the second process (NTVS-Process) in addition to the waste heat, solar radiation is utilised. The subsequent measures--gasification, gas cleaning and electric and thermal power generation--are identical in both processes. The ETVS-Process and the NTVS-Process are self-sustaining in terms of energy use; actually a surplus of heat and electricity is generated in both processes.     

Environmental and economic life cycle assessment for sewage sludge treatment processes in Japan

Life cycle assessment for sewage sludge treatment was carried out by estimating the environmental and economic impacts of the six alternative scenarios most often used in Japan: dewatering, composting, drying, incineration, incinerated ash melting and dewatered sludge melting, each with or without digestion. Three end-of-life treatments were also studied: landfilling, agricultural application and building material application. The results demonstrate that sewage sludge digestion can reduce the environmental load and cost through reduced dry matter volume. The global warming potential (GWP) generated from incineration and melting processes can be significantly reduced through the reuse of waste heat for electricity and/or heat generation. Equipment production in scenarios except dewatering has an important effect on GWP, whereas the contribution of construction is negligible. In addition, the results show that the dewatering scenario has the highest impact on land use and cost, the drying scenario has the highest impact on GWP and acidification, and the incinerated ash melting scenario has the highest impact on human toxicity due to re-emissions of heavy metals from incinerated ash in the melting unit process. On the contrary, the dewatering, composting and incineration scenarios generate the lowest impact on human toxicity, land use and acidification, respectively, and the incinerated ash melting scenario has the lowest impact on GWP and cost. Heavy metals released from atmospheric effluents generated the highest human toxicity impact, with the effect of dioxin emissions being significantly lower. This study proved that the dewatered sludge melting scenario is an environmentally optimal and economically affordable method.     

Development of a high-efficiency rotary dryer for sewage sludge

A rotary drum dryer having an internal rotating body was designed and tested in this study. It was shown that the developed dryer is effective for drying sewage sludge. The best operating conditions in the dryer were low energy input and almost 10% moisture content. The conditions are 255°C for the rotary drum temperature, 17 min for the sludge residence time, and 55 kg/m³ h for the dryer load. Under these conditions, the drying efficiency was 84.8%. The average diameter of dried sludge was less than 8 mm, and the weight reduction rate was 80%. Parametric screening studies achieved the following results. The drying efficiency increased with the increase of the internal temperature and the sludge residence time in the rotary drum, while the drying efficiency decreased when increasing the dryer load. In addition, it was shown that NH₃ and CO₂ were the primary components released from the sewage sludge drying process. The amounts of both of these components increased when the rotary drum temperature was increased.     

Valorization of pellets from municipal WWTP sludge in lightweight clay ceramics

A direct result of the growing number of municipal wastewater-treatment plants (WWTPs) has been an increase in the generation of large amounts of sewage sludge that requires environmentally acceptable final destination. To decrease the volume of sludge, a common technique is drying the sludge at a low temperature in rotary kilns. The result of this process is a granulated material consisting of dehydrated sludge pellets.After this treatment, this pelletized material becomes easier to manipulate, but it also becomes a more toxic waste, containing dangerous substances, mostly of the lipid type. At its final stage, this material is usually incinerated, used as a comburent material, used as an agricultural fertilizer, or used in the cement industry. Each application has its own problems and requires remediation measures from the safety and environmental viewpoints.In this study, we looked beyond these possible applications and analyzed the transformation of sewage sludge through a ceramization process into a material similar to expanded clays; we subsequently explored its uses in the building industry or in the agriculture industry, among others. Both the properties of the product material and the production method were characterized, and an environmental analysis was conducted.The new, lightweight material had a microstructure with open porosity and low thermal conductivity. Environmental characterization such as the leaching test revealed that undetectable amounts of hazardous metals from the sludge were present in the leachate after the sludge went through a thermal treatment, despite their initial presence (with the exception of vanadium, which could pose some restrictions on some of the proposed uses for the final product). Toxicity tests also showed negative results. The study of gaseous emissions during production revealed emissions factors similar to those during the production of conventional clay ceramics, although with higher organic emissions. As for conventional clay ceramics, industrial production would require the implementation of some type of air-depuration system. The results showed that the ceramization of sludge pellets is a promising valorization technique worth considering from both the economic and technological perspectives.     

Integrated drying and incineration of wet sewage sludge in combined bubbling and circulating fluidized bed units

An original integrated drying and incineration technique is proposed to dispose of sewage sludge with moisture content of about 80% in a circulating fluidized bed. This system combines a bubbling fluidized bed dryer with a circulating fluidized bed incinerator. After drying, sewage sludge with moisture less than 20% is transported directly and continuously from the fluidized bed dryer into a circulating fluidized bed incinerator. Pilot plant results showed that integrated drying and incineration is feasible in a unique single system. A 100 t/d Sewage Sludge Incineration Demonstration Project was constructed at the Qige sewage treatment plant in Hangzhou City in China. The operational performance showed that the main operation results conformed to the design values, from which it can be concluded that the scale-up of this technique is deemed both feasible and successful.     

含油污泥的水热法减量处理

采用水热技术处理含油污泥，考察了反应温度和反应时间对水热处理后含油污泥性质的影响，分析了含油污泥的减量化效果。实验结果表明：对含水率为70.6%（w）、含油率为32.0%（w）的含油污泥进行水热处理时，与反应时间相比，反应温度对含油污泥的脱水性能影响更大，是影响含油污泥热水解反应的重要因素;含油污泥经水热处理后，脱水性能得到改善，在所有实验条件下减量化率均高于78.8%，其中，在反应温度190 ℃、反应时间30 min的条件下，减量化率达到88.2%。     

Environmental & economic life cycle assessment of current & future sewage sludge to energy technologies

The UK Water Industry currently generates approximately 800 GW h pa of electrical energy from sewage sludge. Traditionally energy recovery from sewage sludge features Anaerobic Digestion (AD) with biogas utilisation in combined heat and power (CHP) systems. However, the industry is evolving and a number of developments that extract more energy from sludge are either being implemented or are nearing full scale demonstration. This study compared five technology configurations: 1 – conventional AD with CHP, 2 – Thermal Hydrolysis Process (THP) AD with CHP, 3 – THP AD with bio-methane grid injection, 4 – THP AD with CHP followed by drying of digested sludge for solid fuel production, 5 – THP AD followed by drying, pyrolysis of the digested sludge and use of the both the biogas and the pyrolysis gas in a CHP.The economic and environmental Life Cycle Assessment (LCA) found that both the post AD drying options performed well but the option used to create a solid fuel to displace coal (configuration 4) was the most sustainable solution economically and environmentally, closely followed by the pyrolysis configuration (5). Application of THP improves the financial and environmental performance compared with conventional AD. Producing bio-methane for grid injection (configuration 3) is attractive financially but has the worst environmental impact of all the scenarios, suggesting that the current UK financial incentive policy for bio-methane is not driving best environmental practice. It is clear that new and improving processes and technologies are enabling significant opportunities for further energy recovery from sludge; LCA provides tools for determining the best overall options for particular situations and allows innovation resources and investment to be focused accordingly.