污水处理厂污泥处理技术的探讨

近年来,随着社会工业的发展、技术的进步,国民生产总值日益提高。污泥污染问题也逐渐进入人们视线。本文通过对污水处理厂进水水量特征描述,重点探讨污泥处理在我国发展的现状、污水处理厂在污泥处理工程中存在的问题。在此基础上,对污水处理厂污泥处理未来发展趋势展望,提出对于污泥处理技术行之有效的建设性建议。     

剩余污泥资源化利用新工艺研究进展

随着城市化进程加速, 污水处理厂剩余污泥大量产生, 如何对其进行处理并有效资源化利用成为广泛关注的问题。文章在综述我国城市污水处理厂剩余污泥特征、相应处理与综合利用方法的基础上, 进一步综述了污泥干化芦苇床、人工湿地、微生物燃料电池以及相关组合工艺等剩余污泥资源化利用新工艺。总结了各种新工艺的优势以及当前尚未解决的关键问题, 对未来新工艺的潜在应用进行了展望, 以期开发出低能耗、低成本、高效率、绿色生态的技术, 真正实现剩余污泥的减量化、无害化、稳定化和资源化。     

微生物蛋白提取技术化污泥为蛋白

目前对城镇污水处理厂污泥处理较好的方法有2种：焚烧和填埋,但这2种方法都不能从根本上解决污泥处理无害化和资源化的问题。天津裕川公司在微生物蛋白提取方式的污泥处理及资源化技术的研究课题中,采用污泥微生物蛋白提取技术,以CaO为主要水解药剂,在105～185℃下热碱水解提取污泥中微生物蛋白。这一工艺不仅使污泥蛋白回收率超过50％,而且能稳固污泥中的重金属,杀死细菌,回收的微生物蛋白产品质量分数达30％以上。以此为原料可制成性能优良的蛋白发泡剂。     

污泥土地利用对农作物及土壤的影响研究

以沈阳北部污水处理厂污泥为研究对象 ,开展了污泥土地利用对农作物及土壤环境影响的研究 .结果表明 ,污泥土地利用可提高土壤中N、P及有机质含量 .污泥用量为 2 2 .5t·hm-2 和 45t·hm-2 时有利于作物生长发育 ,使水稻生物量与对照相比分别增加了 11.48%、11.83%.污泥施用量只要控制在 45t·hm-2以内 ,污泥中的重金属不会对土壤、农产品质量及地下水产生不良的影响 .     

厌氧氨氧化颗粒污泥聚集机制研究进展

厌氧氨氧化(anaerobic ammonium oxidation,anammox)工艺被认为是当前污水生物脱氮领域最经济的处理工艺,有利于实现污水处理厂的能源自给。厌氧氨氧化菌是该工艺的核心功能微生物。以厌氧氨氧化菌为主导微生物形成的厌氧氨氧化颗粒污泥具有沉速大、污泥持留能力强及对不利环境抵抗能力强等突出优势,是实现厌氧氨氧化工艺最有前景的污泥形态。本论文围绕厌氧氨氧化颗粒,介绍了厌氧氨氧化菌的特性、种类及代谢途径,综述了厌氧氨氧化颗粒污泥的形成假说及与厌氧氨氧化颗粒污泥聚集密切相关的胞外聚合物(extracellular polymeric substance,EPS)和群体感应研究现状,并对今后厌氧氨氧化颗粒的研究进行了展望,以期为后续厌氧氨氧化颗粒的研究及厌氧氨氧化颗粒工艺的优化提供参考。     

污泥减量化污水处理技术进展

剩余污泥的处理已成为污水生物处理技术普及和运行的制约因素。解决剩余污泥处理与处置的首要原则就是污泥减量化,它包含两方面的含义:减少污泥产生量(污泥减质)和减少污泥容积(污泥减容)。传统的污泥处理主要是采用浓缩、脱水和干燥等方法降低污泥的含水率,进而减少污泥容积,以便于后续的污泥运输和处置。这种方法不仅处理费用昂贵,增加了污水处理厂的建设和运行成本,而且无法从根本上减少污泥的干物质量。近年来,越来越多的研究开始着眼于从源头上减少剩余污泥产生量(污泥减质),成为污泥减量化污水处理技术的重要发展方向。文章对污泥减量化原理与工艺以及原位污泥减量污水处理技术进行了综述。     

中国城市污泥土地利用关注的典型有机污染物

污泥土地利用是国内外城市污泥主要的处置方式之一,而污泥中的有机污染物是污泥土地利用的限制性因素之一.本文分析了国内外城市污泥中有机污染物的浓度和研究现状,针对我国国情,认为多环芳烃(PAHs)是城市污泥中一种常见的有机污染物,总含量一般在1 ～ 10 mg·kg-1,有的因污水来源复杂而超过了100 mg·kg-1;壬基苯酚(NP/NPE)在我国污水处理厂污泥样品中均有检出,浓度在1～128 mg·kg-1.污泥园林绿化、林地利用、土壤改良等将是今后主要的利用方向,要实现污泥安全、环保的土地利用,多环芳烃(PAHs)和壬基苯酚(NP/NPE)将是主要考虑的典型有机污染物.     

施用污泥对小白菜生长及其迁转重金属的影响

采用盆栽方式,以厦门市筼筜污水处理厂的污泥作为有机肥种植小白菜,探讨污泥施用对小白菜生长和产量的影响及重金属在小白菜-土壤间的迁移转化和积累情况.结果表明:污泥中氮、磷、钾和有机质含量丰富,重金属含量均低于国家农用污泥中污染物控制标准;适宜的污泥施用量可促进小白菜的生长,污泥用量为5%时,小白菜长势最好,生物量最大;污...     

两个污水处理系统的能值与经济综合分析

运用改进的能值评价指标和经济指标对构建的两个污水处理综合系统("污水处理厂处理+脱水污泥填埋"及"污水处理厂处理+脱水污泥填埋+中水回用")进行了环境可持续性和经济竞争力的综合分析。改进的能值指标(能值产出率SEYR、环境负载率SELR、环境可持续发展指数SESI和能值受益率SEBR)是在考虑研究对象废物及产物能值对环境影响的基础上提出的,更好地反映了系统的特征。结果表明,中水回用系统的增加有利于提升系统的环境可持续发展能力;"污水处理厂处理+脱水污泥填埋+中水回用"系统较"污水厂处理+脱水污泥填埋"系统的经济竞争力差,但却拥有更强的可持续发展能力,有利的经济政策能够刺激其更好的推广运用。     

污泥的农林处置与利用

1　污泥处置与农林利用现状污泥处置与利用 ,乃当前环境科学中的重要课题。一些污水处理的专家认为 ,污泥处置是污水处理厂当前迫切要解决的难度最大的问题。污泥的处置主要包括农用、填埋、焚烧、排海等。据1 996年资料报道 ,世界上 1 2个发达国家对污泥的处置方式 (表 1 ) ,45.3%为农用 ,38%为填埋 ,1 0 .5%为焚烧 ,6.0 %为排海。西欧、美国和英国的污泥处置 ,西欧以填埋为主 ,美国和英国以农用为主 ,加拿大以焚烧为主 (占 40 % ) [1 ] 。 1 991年和1 998年 ,美国和欧盟已规定禁止向海洋倾倒污泥[1 1 ] ,并且一些发达国家已经明令禁止焚烧…     

New sludge pretreatment method to improve dewaterability of waste activated sludge

The enhancements of electrolysis-pretreated conditioning were investigated in this study. Normalized capillary suction time (CST) was used to evaluate sludge dewaterability. Extracellular polymeric substance (EPS) concentration, viscosity and scanning electron microscopy (SEM) were determined to explain the observed changes in conditioning process. It indicated that pretreatment at 50 v and 5 min with Ti/RuO₂ anode was determined to be the optimal condition, which generated the lowest normalized CST and optimal soluble EPS concentration, leading to the decreasing of viscosity. EPS had positive correlation with the normalized CST. Subjecting to a combination of electrolysis pretreatment and flocculants conditioning, 50% dosage of cationic polyacrylamide (PAM) could be reduced. When co-conditioned with electrolysis and polymerization ferric sulfate (PFS), it did not present any clear advantages over PFS conditioning alone. Furthermore, SEM investigation indicated that electrolysis pretreatment could rupture sludge, release the interstitial water and extracellular substances, especially protein and polysaccharide, and consequently enhance its dewaterability.     

Preliminary results of afforestation of brackish sludge mounds

High population density and intensive use of land in Flanders (Northern Belgium) have resulted in a shortage of land to dump dredged sediments. In search of an area efficient solution, a mound was constructed and afforested; 50–114% more dredged sediment per unit area could be discarded by constructing mounds with a height of 6.6 m compared to conventional disposal sites. To prevent erosion, the mound was afforested. Preliminary results of tree growth and changes in soil conditions are demonstrated. Tree survival and height growth are highest in the dominant wind direction sc. the SW-NE axis. On the slopes, parallel with the dominant wind direction, tree mortality up to 80% was observed. The increase of the soil organic carbon content from 3.1 to 3.8% could be partly put down to the growth of tree roots. This increase in organic carbon has far-reaching consequences for potential soil sanitation. The high amount of CaCO₃ in the soil protects the mound from internal or external acidification for the next centuries. After four growing seasons, electric conductivity was reduced to the threshold for salt sensitive plants.     

Heavy metal fractionation and organic matter stabilization in sewage sludge treatment wetlands

The presence of heavy metals in sludge stabilized in a reed bed system may affect its use for agricultural purposes. However, the environmental impact of sludge depends on the availability and phytotoxicity of these heavy metals.The aim of this research was to determine the effectiveness of a reed bed (Phragmites australis) sludge treatment system in two urban wastewater treatment plants in Italy after a three-year period of operation: (i) by estimating the process of sludge stabilization, following conventional and nonconventional parameters related to the evolution of organic matter quality (water soluble carbon, dehydrogenase activity, pyrolytic fragments); (ii) by following the heavy metal bioavailability in the sludge through their fractionation. For heavy metal fractionation, the Community Bureau of Reference (BCR) was followed.The results showed that there was mineralization and stabilization of sludge over time, suggested by the decrease of about 35% in water soluble carbon and of about 60-80% of dehydrogenase activity. Moreover, significant values of benzene (17%), toluene (31%) and phenol (9%) were found at the end of experimentation in both treatment wetlands, highlighting the re-synthesis of humic-like matter.The results also showed that the content of heavy metals after 30 months was associated with the less mobile fractions of the sludge (more than 60% of total heavy metal content for almost metal), in particular, the fraction linked to the organic matter.     

Recent advances in membrane bio-technologies for sludge reduction and treatment

This paper is designed to critically review the recent developments of membrane bio-technologies for sludge reduction and treatment by covering process fundamentals, performances (sludge reduction efficiency, membrane fouling, pollutant removal, etc.) and key operational parameters. The future perspectives of the hybrid membrane processes for sludge reduction and treatment are also discussed. For sludge reduction using membrane bioreactors (MBRs), literature review shows that biological maintenance metabolism, predation on bacteria, and uncoupling metabolism through using oxic-settling-anaerobic (OSA) process are promising ways that can be employed in full-scale applications. Development of control methods for worm proliferation is in great need of, and a good sludge reduction and MBR performance can be expected if worm growth is properly controlled. For lysis-cryptic sludge reduction method, improvement of oxidant dispersion and increase of the interaction with sludge cells can enhance the lysis efficiency. Green uncoupler development might be another research direction for uncoupling metabolism in MBRs. Aerobic hybrid membrane system can perform well for sludge thickening and digestion in small- and medium-sized wastewater treatment plants (WWTPs), and pilot-scale/full-scale applications have been reported. Anaerobic membrane digestion (AMD) process is a very competitive technology for sludge stabilization and digestion. Use of biogas recirculation for fouling control can be a powerful way to decrease the energy requirements for AMD process. Future research efforts should be dedicated to membrane preparation for high biomass applications, process optimization, and pilot-scale/full-scale tracking research in order to push forward the real and wide applications of the hybrid membrane systems for sludge minimization and treatment.     

Upgrading activated sludge systems and reduction in excess sludge

Most of 200 Activated Sludge Plant in Iran are overloaded and as a result, their efficiency is low. In this work, a pilot plant is manufactured and put into operation in one of the wastewater treatment plants in the west of Tehran. Instead of conventional activated sludge, a membrane bioreactor and an upflow anaerobic sludge blanket reactor used as a pretreatment unit in this pilot. For the sake of data accuracy and precision, an enriched municipal wastewater was opted as an influent to the pilot. Based on the attained result, the optimum retention time in this system was 4h, and the overall COD removal efficiency was 98%. As a whole, the application of this retrofit would increase the plant's capacity by a factor of 5 and reducing the excess sludge by a factor of 10. The sludge volume index in the anaerobic reactor was about 12 after granulation occurred.     

Systematic analysis of biochemical performance and the microbial community of an activated sludge process using ozone-treated sludge for sludge reduction

Two lab-scale bioreactors (reactors 1 and 2) were employed to examine the changes in biological performance and the microbial community of an activated sludge process fed with ozonated sludge for sludge reduction. During the 122 d operation, the microbial activities and community in the two reactors were evaluated. The results indicated that, when compared with the conventional reactor (reactor 1), the reactor that was fed with the ozonated sludge (reactor 2) showed good removal of COD, TN and cell debris, without formation of any excess sludge. In addition, the protease activity and intracellular ATP concentration of reactor 2 were increased when compared to reactor 1, indicating that reactor 2 had a better ability to digest proteins and cell debris. DGGE analysis revealed that the bacterial communities in the two reactors were different, and that the dissimilarity of the bacterial population was nearly 40%. Reactor 2 also contained more protozoa and metazoa, which could graze on the ozone-treated sludge debris directly.     

Excess sludge reduction by biological way: from experimental experience to a real full scale application

The aim of this study was to investigate the ability of a biological process applied in the sludge line and based on the alternation of oxic and anoxic phases, to minimize the waste sludge production. After some tests in pilot scale, the process was applied in a real municipal wastewater treatment plant of 35,000 PE trying out one setting of working experimental conditions. A rate of the recycle flow was conditioned in a treatment basin, maintaining an HRT of 10 days. The control device operated for the 50% of time in the ORP range between -400 and -200 mV, and for the 50% in the ORP range between -200 and +50 mV. The mass balance defined an actual observed growth yield equal to 0.09 kgTVSkgCODr(-1), and the heterotrophic yield values, assessed by batch tests, seemed to be a suitable marker for the sludge reduction and for the energy uncoupling.     

Dewatering fibrous sludge with soy protein

Sludge is typically conditioned with petroleum-based polymers such as cationic polyacrylamides (c-PAMs) prior to dewatering. It is shown that soy and whey proteins can function as sludge conditioners. High cake solids are obtained when fiber or fibrous sludge is dewatered after treatment with a crude soy flour hydrolysate. Filtrate turbidity is not reduced by the soy alone, but it can be significantly lowered with a small c-PAM supplement. The approach is demonstrated with wood pulp fiber and several paper mill sludges. The binding of soy protein to sludge solids is much weaker than that of c-PAM, but it still produces a denser cake because charge reversal is reduced. Although soy protein and sludge particles are both negatively charged overall they both contain positively charged groups that facilitate bonding. The cost:benefits of c-PAM supplemented soy protein are attractive when compared to a full c-PAM dose. In addition, the soy product has a green value.     

The characteristics of organic sludge/sawdust derived fuel

A fundamental study of the characteristics of a sludge refuse-derived fuel (RDF) and the combustion behaviors were done. The test data demonstrate good results for the development of energy recovery technology of organic sludge or waste. The ash deposit formation propensity has been based on pretreatment, temperature and the ratio of organic sludge to sawdust. The usage of organic sludge and waste as an alternative fuel is cost effective and has environmental benefits.     

Effect of initial physical characteristics on sludge compost performance

To develop an active microbial activity quickly developing stabilizing thermophilic temperatures during the composting of wastewater sludge, the bulking agent (BA) plays a major role in establishing the recipe structure, exposed particle surface area and porosity. To optimize the biodegradation of a sludge compost recipe, the objective of this paper was to study the effect and interaction of initial moisture content (MC) and BA particle size distribution. Three 300 L insulated laboratory composters were used to treat two series of ten (10) recipes with different combinations of MC and BA particle size distribution. Using a to wastewater sludge to BA dry mass ratio of 1/6, the ten (10) recipes were repeated using two BA, residues recycled from a commercial sludge composting plant and crushed wood pallets. Each four week trial monitored O₂ uptake, temperature, compost consolidation and airflow distribution. The Central Composite Factor Design method produced a model from the results estimating the impact of a wider range of MC and BA particles size distribution. The MC directly affected the total O₂ uptake and therefore, organic matter biodegradation. The BA particle size distribution influenced compost consolidation with a MC crossed effect. Both BA particle size distribution and MC influenced compost airflow dispersion. Composting was optimized using the BA consisting of recycled green waste residues with particle size of 20–30 mm and a 55% MC. The predictive models suggested the need for further optimization of sludge and wood residue composting recipe.