湿式氧化处理剩余污泥的研究

采用湿式氧化处理剩余污泥 ,以化工污泥为对象 ,研究了温度、压力、反应时间对污泥过滤性能和沉降性能的影响 ,以及污泥中有机物、氮、磷、硫的变化情况 ,并采用扫描电镜对湿式氧化前后污泥的结构进行了分析。选择了比较温和的湿式氧化条件 ,此条件下可使污泥中的有机物大部分氧化并转入到水相 ,气固液分离后 ,上清液可生化性较好 ,BOD/COD >0 5 1;气体可直接排入大气 ,无二次污染 ,固相的沉降性能和过滤性能得到了明显改善 ,污泥比阻为 2 4 3× 10 8s2 /g。采用该工艺条件对炼油污泥和城市污泥进行处理也获得了良好的效果。     

臭氧处理对剩余污泥减量化、资源化与无害化的影响研究进展

臭氧作为强氧化剂和杀菌剂,此前被广泛应用于污水处理系统以改善污水出水水质,近年来在剩余污泥原位减量方面得到了广泛的关注.首先,总结了臭氧处理对剩余污泥原位减量和脱水性能的影响;其次,归纳了臭氧联合厌氧消化技术对污泥资源化的促进作用;接着,从无害化角度总结了臭氧处理对污泥中痕量有机物降解的影响;最后,对臭氧处理污泥技术的...     

污泥减量技术

介绍了目前国内外一些污泥减量的技术和工艺 ,如 :原生动物和后生动物摄食细菌法 ,能减少污泥产量 60 %以上 ,对于固定式淹没生物膜法甚至没有剩余污泥产生 ;微生物强化法 ,利用外投优化菌种减少污泥排放量 1 6% ;投加酶法 ,将难溶解的大分子有机污染物分解为易于微生物吸收和利用的小分子溶解性有机物 ,既有利于有机污染物的降解 ,又能促进细菌的增殖 ,能减少污泥产量50 % ;此外还介绍了超声波技术、臭氧氧化、Cambi工艺和生物细胞溶解系统等一系列方法。     

臭氧氧化剩余污泥的影响因素分析及应用初探

通过小试得出臭氧氧化剩余污泥的最佳作用条件,并将该作用条件应用于实际废水的剩余污泥减量化中,进行能耗分析。在臭氧氧化污泥过程中,采用单因素分析法分别考察臭氧投加量、剩余污泥浓度、碱解以及热解预处理对污泥减量的影响。在小试基础上,结合实际情况,对某污水处理厂污泥进行了不同污泥浓度下的减量试验,验证了小试结果,得出针对该种污泥MLSS=8.287kg/m3,臭氧最佳投加量在0.038gO3/gMLSS左右,所需能耗为0.589kW.h/kgMLSS。     

剩余污泥减量化技术研究进展与发展趋势

按照物理、化学、生物及组合工艺的分类对污泥减量技术的研究发展状况进行了分析,并 通过污水处理效果来评价各污泥减量工艺。总结出污泥减量化的两个发展趋势:通过调整反应器和 工艺参数实现在污泥产生过程中减少污泥产量;在污泥回流过程中通过细胞溶解实现在污泥产生后 减少污泥外排量。     

污泥处理技术发展

综述目前污泥处理技术的发展概况,介绍污泥减量化和资源化技术,分别从超声波破解、微型动物捕食、臭氧氧化和污泥解偶联等方面介绍了污泥减量化的最新工艺技术;从利用剩余污泥做碳源、建材、肥料及制油等方面总结了污泥资源化的最新成果。     

转鼓浓缩工艺中剩余污泥性质对絮凝剂投配率的影响

小红门污水处理厂污泥处理采用转鼓式浓缩机进行剩余污泥浓缩,采用带式压滤机对浓缩后污泥进行脱水.经过两年的实际运行,考察了浓缩过程中剩余污泥性质变化对絮凝剂投配率的影响规律.结果表明,在保证相同的污泥浓缩效果下,剩余污泥含水率为99.2%～98.9%时,投配率最低;剩余污泥的SVI为100～250 mL/g时,投配率最低;投加PAC进行化学除磷时,投配率将上升约10%;冬季时的投配率明显高于夏季.在此基础上,讨论了如何通过工艺调整保持合适絮凝剂投配率.     

载锰污泥活性炭催化臭氧氧化草酸废水的研究

为研究在催化臭氧化过程中,载锰污泥活性炭对草酸废水降解的催化效果,以及为污泥的资源化探索一条新途径,本实验采用连续流臭氧氧化实验,通过单因素实验方法考察了载锰污泥活性炭催化臭氧化反应的主要影响因素及最佳反应条件,同时对催化臭氧化反应机理进行了探讨。结果表明:在臭氧浓度为5.0 mg/L,载锰污泥活性炭投加量为100 mg/L,pH值为3.5的最佳反应条件下,60 min内草酸的去除率最高达91.2%。叔丁醇对草酸降解具有抑制作用,催化臭氧化反应符合羟基自由基的反应机制。该方法的处理效果较为明显,对评价催化臭氧法的效果具有较明显的参考价值。     

两相厌氧处理湿式氧化后剩余污泥的研究

针对工业废水剩余污泥可生化性差、处理费用高等问题,以石油化工废水剩余污泥为研究对象,进行了湿式氧化后两相厌氧处理的研究。即剩余污泥经温和的湿式氧化预处理后,有机物从微生物体内释放出来并转移到液相,上清液采用两相厌氧处理。系统研究了两相厌氧中 COD_(Cr)、产气量、BOD_5、N、SO_4~(2-)的变化,以及水力停留时间对处理效率的影响,对影响两相厌氧的主要因素讲行了分析。     

超临界水氧化技术在城市污泥处理中的应用

综述了超临界水氧化(SCWO)技术的基本原理和工艺、在城市污泥处理中应用的国内外研究进展,并就SCWO处理城市污泥的前景作了展望。SCWO技术处理城市污泥,污泥中有机物的去除率可达99.9%以上,污泥氧化后的最终残余固体产物的容积仅为浓缩污泥容积的1.2%左右,反应后剩余收集液的COD质量浓度小于10 mg/L,处理后的残留固体还可以进行磷酸盐和重金属回收。     

Performance of high-rate sludge digesters fed with sonicated sludge.

A major limitation of anaerobic sludge digestion is the long hydraulic retention time (HRT) required for satisfactory stabilization which results in large digester size. This study explored a possibility of operating digesters at shortened HRTs by sonication pretreatment of secondary sludges. Four identical digesters designated D1, D2, D3 and D4 were fed with untreated and sludge sonicated at densities of 0.18 W/ml, 0.33 W/ml and 0.52 W/ml, respectively. All digesters were operated at three HRTs of 8-day, 4-day and 2-day. Comparing with the control digester (D1), total solids removal efficiencies improved by 12-19%, 17-36% and 20-39% in digesters D2, D3 and D4, respectively. The volatile solids removal was also increased by 11-21%, 17-33% and 19-36% in the respective digesters. The improved solids degradation corresponded with increase in biogas production by 1.4-2.5, 1.9-3.0 and 1.6-3.1 times, respectively. Increase in methane composition by 2-17% was also noted in all digesters fed with sonicated sludge. An analysis indicated that sonication pretreatment could enhance degradation of carbon, nitrogen and sulfur substances in the digestion. The study suggested that sonication of sludge is a possible pretreatment to shorten the digester operating HRT with improvement in solids degradation, biogas production and methane content. It can be deduced that to maintain a consistent solids loading at a desire performance, sludge digester with smaller size can be designed.     

Anaerobic thermophilic digestion of sewage sludge with a thickened sludge recycle

The process of anaerobic thermophilic digestion of municipal wastewater sludge with a recycled part of thickened digested sludge, was studied in semi-continuous laboratory digesters. This modified recycling process resulted in increased solids retention time (SRT) with the same hydraulic retention time (HRT) as compared with traditional digestion without recycling. Increased SRT without increasing of HRT resulted in the enhancement of volatile substance reduction by up to 68% in the reactor with the recycling process compared with 34% in a control conventional reactor. Biogas production was intensified from 0.3 L/g of influent volatile solids (VS) in the control reactor up to 0.35 L/g VS. In addition, the recycling process improved the dewatering properties of digested sludge.     

Aerobic granular sludge technology: an alternative to activated sludge?

Laboratory experiments have shown that it is possible to cultivate aerobic granular sludge in sequencing batch reactors. In order to direct future research needs and the critical points for successful implementation at large scale, a full detailed design of a potential application was made. The design was based on the laboratory results, and two variants of a full-scale sewage treatment plant based on Granular sludge Sequencing Batch Reactors (GSBRs) were evaluated. As a reference a conventional treatment plant based on activated sludge technology was designed for the same case. Based on total annual costs both GSBR variants proved to be more attractive than the reference alternative (7-17% lower costs). From a sensitivity analysis it appeared that the GSBR technology was less sensitive to the land price and more sensitive to a rain weather flow (RWF). This means that the GSBR technology becomes more attractive at lower permissible RWF/DWF ratios and higher land prices. The footprint of the GSBR variants was only 25% compared to the reference. However, the GSBR with primary treatment only cannot meet the present effluent standards for municipal wastewater in The Netherlands, mainly because of a too high suspended solids concentration in the effluent. A growing number of sewage treatment plants in the Netherlands are going to be faced with more stringent effluent standards. In general, activated sludge plants will have to be extended with a post treatment step (e.g. sand filtration) or be transformed into Membrane Bioreactors. In this case a GSBR variant with primary treatment as well as post treatment can be an attractive alternative.     

用污泥沉降比指导活性污泥法运行的探讨

总结讨论了污泥沉降比在活性污泥法污水处理过程中与MLSS的关系和对活性污泥法处理效果的影响,分析其与季节变化的关系,指出污泥沉降比在预防污泥膨胀及维持曝气池稳定运行方面的作用,影响污水处理效果因素之间的关系,以及污泥沉降比在实际生产运行管理中的指导作用。     

Co-conditioning and dewatering of alum sludge and waste activated sludge.

Co-conditioning and dewatering behaviors of alum sludge and waste activated sludge were investigated. Two different sludges were mixed at various ratios (2:1; 1:1; 1:2; 1:4) for study. Capillary suction time (CST) and specific resistance to filtration (SRF) were utilized to assess sludge dewaterability. Relatively speaking, waste activated sludge, though of higher solid content, was more difficult to be dewatered than alum sludge. It was found that sludge dewaterability and settlability became better with increasing fraction of alum sludge in the mixed sludge. Dosage required of the cationic polyelectrolyte (KP-201C) for dewatering was reduced as well. It is proposed that alum sludge acts as skeleton builder in the mixed sludge, and renders the mixed sludge more incompressible which is beneficial for sludge dewatering. Implications of the results of the study to the sludge management plan for Taipei City that generates both alum sludge and waste activated sludge at significant amount are also discussed. The current sludge treatment and disposal plan in Metropolitan Taipei could be made more cost-effective.     

Impact of sludge retention time on sludge characteristics and microbial community in MBR

In this study, the impact of sludge retention time (SRT) on sludge characteristics and microbial community and the effect on membrane fouling in membrane bioreactor (MBR) was investigated. The results show that MBR with longer SRT has less fouling propensity, in agreement with other studies, despite the fact that the MBR with longer SRT contained higher MLSS and smaller particle size. However, much more soluble microbial products (SMPs) were released in MBR with shorter SRT. More slime on the membrane surface was observed in MBR with shorter SRT while sludge cakes formed on the membrane surface in MBR with longer SRT. The results show that SMP contributes to the severe fouling observed in MBR with shorter SRT, which is in agreement with other studies showing that SMPs were the major foulants in MBR. Under different SRTs of operation, the bacterial community structures of the sludge obtained by use of polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) were almost identical, but those on the membrane surface differed substantially. It suggests that, although SRT has impact on sludge characteristics, it doesn't affect the microbial community in the suspension.     

Rapid start-up of a nitrifying reactor using aerobic granular sludge as seed sludge

In this study, the effectiveness of aerobic granular sludge as seed sludge for rapid start-up of nitrifying processes was investigated using a laboratory-scale continuous stirred-tank reactor (CSTR) fed with completely inorganic wastewater which contained a high concentration of ammonia. Even when a large amount of granular biomass was inoculated in the reactor, and the characteristics of influent wastewater were abruptly changed, excess biomass washout was not observed, and biomass concentration was kept high at the start-up period due to high settling ability of the aerobic granular sludge. As a result, an ammonia removal rate immediately increased and reached more than 1.0 kg N/m(3)/d within 20 days and up to 1.8 kg N/m(3)/d on day 39. Subsequently, high rate nitritation was stably attained during 100 days. However, nitrite accumulation had been observed for 140 days before attaining complete nitrification to nitrate. Fluorescence in situ hybridization analysis revealed the increase in amount of ammonia-oxidizing bacteria which existed in the outer edge of the granular sludge during the start-up period. This microbial ecological change would make it possible to attain high rate ammonia removal.     

Analysing sludge balance in activated sludge systems with a novel mass transport model

In activated sludge systems the mechanically treated wastewater is biologically cleaned by biomass (activated sludge). The basic requirement of an efficient biological wastewater treatment is to have as a high biomass concentration in the biological reactor (BR) as possible. The activated sludge balance in activated sludge systems is controlled by the settling, thickening, scraper mechanism in the secondary settling tank (SST) and sludge returning. These processes aim at keeping maximum sludge mass in the BR and minimum sludge mass in the SST even in peak flow events (storm water flow). It can be, however, only reached by a high SST performance. The main physical processes and boundary conditions such as inhomogeneous turbulent flow, geometrical features of the SST, wastewater treatment plant (WWTP) load, return sludge flow, sludge volume index etc. all influence settling thickening and sludge returning. In the paper a novel mass transport model of an activated sludge system is presented which involves a 2-dimensional SST model coupled with a mixed reactor model of the biological reactor. It makes possible to investigate different sludge returning strategies and their influence on the sludge balance of the investigated activated sludge system, furthermore, the processes determining the flow and concentration patterns in the SST. The paper gives an overview on the first promising model results of a prevailing peak flow event investigation at the WWTP of Graz.     

Mineralisation of hazardous organic compounds in a sludge reed bed and sludge storage.

Linear alkylbenzene sulphonates (LAS) and nonylphenolethoxylates (NPE) may be detrimental to the environment if spread in inappropriately large concentrations. Mineralisation of LAS and NPE in mesophilic digested sludge was observed during a 9-month monitoring programme where three separate treatment methods were investigated. Sludge was treated in a sludge reed bed under aerobic conditions, by storage in a container under anaerobic conditions, and by storage in a sludge pile turned over mechanically at intervals to improve the oxygen influx. Treatment in a sludge reed bed was shown to be effective. Mineralisation of 98% of LAS and 93% of NPE was observed. Only limited mineralisation occurred on the surface of the sludge stored in a container. A reduction of LAS and NPE of 90% and 43%, respectively, was observed in the sludge which was stored in a pile and frequently turned.     

Chemical conditioning of sludge.

With all the advances made in understanding the structure and composition of sewage sludges, chemical conditioning remains a trial and error process, both with regard to the type and dose of conditioner needed. Recent studies at Virginia Tech have found that biological floc consists of two types of biopolymer, material associated with iron and aluminium and material associated with calcium and magnesium. These materials behave differently when sludges undergo digestion. This results in very different material being released into solution during digestion and very different conditioning requirements. This study shows that the primary materials released during anaerobic digestion are proteins and coagulation of the colloidal protein fraction in solution is the primary mechanism for conditioning. For aerobically digested sludges, both proteins and polysaccharides make up the colloid fraction, which interferes with dewatering. This research also shows that the effectiveness of the digestion process as characterized by volatile solids destruction is directly related to the chemical dose required for conditioning. That is, as the solids destruction increases, the conditioning chemical requirement also increases. Well digested sludges dewater more poorly and require more conditioning chemical than those with less volatile solids destruction.