生物沥浸对城市污泥脱水及其重金属去除的影响

利用沥浸微生物对浓缩污泥与添加聚丙烯酰胺(PAM)的脱水污泥进行生物沥浸处理,同时采用厢式压滤机在0.35 MPa的压力条件下,对生物沥浸前后的污泥进行脱水。结果表明,经过生物沥浸处理,浓缩污泥与稀释后的脱水污泥的CST值可分别降至11.8、14.6 s;沥浸结束后静置24 h,上清液所占比例分别从原来的12.5%、24%升至31%、42%,两种污泥中Zn的溶出率分别为66.65%、59.13%,Cu的溶出率分别为13.31%、23.55%。对浓缩污泥直接进行压滤脱水,泥饼含水率高达75%;加PAM调理后再脱水,泥饼含水率达68%;而经生物沥浸后再脱水,泥饼含水率可降至58%。可见,在相同脱水条件下,生物沥浸法对污泥的调理作用要优于PAM。     

污泥生物沥浸深度脱水工艺用于污水厂提标扩建

南宁市江南污水处理厂水质提标及三期扩建工程完成后污水总处理规模将达到72×10⁴ m³/d,预计污泥产量为500 t/d(含水率为80%)。为进一步推动污泥的处理处置实现无害化、减量化,并为稳定化和资源化创造良好的条件,该污水处理厂新建了污泥处理系统,采用生物沥浸深度脱水工艺,产出泥饼不再黑臭,含水率降至60%以下,体积比浓缩污泥减少90%～95%。经过近一年的试运营,在75%的生产负荷下,可稳定产出含水率约60%的泥饼约80 t/d,基本实现设计目标。总结了生物沥浸深度脱水工艺的中试、工程建设以及调试运行的主要内容,列出了较为详尽的试验数据及工艺参数,对其他类似污泥处理系统的设计及运行具有借鉴意义。     

污泥深度脱水协同垃圾焚烧生产性试验研究

针对北方某城市200 t/d污泥集中处置项目进行模拟工业化生产的试验研究,以探索污泥深度脱水协同生活垃圾焚烧相关工艺条件及其稳定性。考察了不同工况下污泥脱水速率、泥饼含水率、低位热值以及冬季严寒环境下脱水泥饼的物理性能。结果表明,使用厢式隔膜压滤机,采用聚合氯化铝(PAC)和石灰作为调理剂,通过调整药剂投加比例,在PAC投加量为污泥干基的5%~7%、石灰投加量为污泥干基的10%~20%的情况下,经厢式隔膜压滤机深度脱水后,泥饼含水率可以达到44. 0%~58. 5%,低位热值为3. 25~4. 22 MJ/kg,脱水周期为2. 6~4 h,化学调理药剂成本为37~57元/t(含水率约为80%),泥饼低位热值可以满足垃圾焚烧炉入炉要求;泥饼在有条件储存或晾晒时可显著降低含水率,提高低位热值。     

两级AO+内置式超滤+两级纳滤工艺处理垃圾渗滤液

设计采用两级AO+内置式超滤+两级纳滤工艺处理天津市某垃圾填埋场渗滤液,处理规模为700 m³/d。一级纳滤浓缩液采用两级芬顿高级氧化处理工艺,出水回流至均衡池,处理规模为218 m³/d;二级纳滤浓缩液直接回流至超滤出水池。生化系统产生的生化污泥和浓缩液处理系统产生的化学污泥,分别经浓缩压滤脱水后含水率达到60%,生化污泥脱水滤液回流至均衡池,化学污泥脱水滤液回流至一级芬顿反应池,泥饼运至填埋场填埋处置。系统建成后运行至今,出水水质满足《生活垃圾填埋场污染控制标准》(GB 16889—2008)中的表2标准,COD、NH₃-N、TN及TP总去除率分别达到99.3%、99.9%、99.0%、92.3%。该工艺处理效果良好、运行稳定、自动化程度高。项目的实施解决了该垃圾填埋场渗滤液处理能力不足的问题,具有良好的环境效益和社会效益。     

生物沥浸法对常规脱水污泥再深度脱水的效果

为了考察生物沥浸法对常规脱水污泥(指在浓缩污泥中加PAM等高分子絮凝剂并经带式或离心脱水后获得的含水率在80%左右的脱水污泥)进一步深度脱水的效果,将常规脱水污泥用中水稀释成含水率为97%左右的液态污泥后,采用批式运行模式进行生产性生物沥浸法调理(每批次处理污泥为60 m3),然后在不加任何化学絮凝剂的情况下直接用隔膜厢式压滤机进行压滤脱水。结果表明,以浓缩池含水率为97%的浓缩污泥作为对照,在上批次沥浸污泥(接种物)与待处理的液态污泥体积比为1∶1时,生物沥浸过程可在24 h内完成,污泥比阻由沥浸初期的3.56×1012m/kg降低至0.43×1012m/kg。生物沥浸后的污泥通过150 m2的隔膜厢式压滤机,在1.2~1.5 MPa压力下压滤1.5 h,泥饼含水率可稳定地降低到60%以下,外观呈土黄色块状,无臭味。经检测,泥饼有机质和高位热值在生物沥浸处理前后没有降低,且压滤液清澈,无色无味,COD为120~170 mg/L,总氮为40~60 mg/L,总磷在0.5 mg/L以下。可见,常规脱水污泥经稀释后进行生物沥浸法深度脱水处理是完全可行的。     

掺加页岩后污泥沉降浓缩效果与利用

改善污水污泥浓缩和脱水性能有利于污泥的处置和利用。试验研究了页岩细度和掺量在污泥沉降浓缩过程中的作用。结果显示,页岩粉细度为250~150μm,掺量≤5(时,掺加页岩粉可改善污泥沉降浓缩性能,沉降浓缩后污泥体积没有明显增加;掺加5%页岩的污泥沉降浓缩后含水率可控制在80%左右,经过离心脱水后含水率可降低至60%以下。试验结果还表明,虽然掺加页岩的污泥脱水后体积有一定程度增加,但可以明显改善污泥的性态,减少资源化利用中与页岩混合过程,还能明显降低污泥的气味;经页岩改性后浓缩脱水得到的污泥能用于烧制轻质陶粒。     

影响污泥深度机械压力脱水因素的探讨

根据污泥处理处置技术在实际应用中存在的缺陷,指出污泥的深度脱水是污泥处理处置的关键环节。因此,污泥深度脱水技术面临着巨大的技术需求和市场需求。介绍了污泥深度脱水性能的表征方法,指出模拟恒压压滤脱水后泥饼的含水率能够较好地表征污泥深度脱水性能。同时,从污泥性质、调理剂预处理、过滤压力及操作、过滤介质等方面分析了污泥深度机械压力脱水的影响因素。     

某污水处理厂污泥处理系统技术改造

湖北十堰某污水处理厂对污泥处理系统进行技术改造,采用机械浓缩/调理改性/高压压滤工艺对污泥进行深度脱水处理。深度脱水后污泥含水率由99. 5%降至60%以下,满足《城镇污水处理厂污泥处置混合填埋用泥质》(GB/T 23485—2009)的要求,有效解决了其污泥处理系统脱水性能较差的问题。     

东莞运河樟村水质净化厂污泥处理系统技术改造

东莞运河樟村水质净化厂是目前国内最大的污染河道水质净化厂,其污泥处理采用重力浓缩/机械脱水工艺.一期工程于2004年春季投入生产运行后,污泥处理系统存在浓缩池浓缩效果不佳、浓缩池未设计放空系统、污泥脱水机脱水能力不足、泥饼含水率不能达标和污泥脱水机房操作环境恶劣等问题.为此提出了增加浓缩池加药和放空系统、增加机械浓缩机和离心脱水机系统以及增加脱水机房除臭系统等技改方案.2005年-2006年实施改造后,有效解决了污泥处理系统处理能力不足和泥饼含水率不能达标等问题,改善了厂区员工的生产操作环境和厂区环境,达到了预期效果.     

污泥低温真空脱水干化工艺的工程应用

污泥低温真空脱水干化工艺在板框压滤机的基础上增加抽真空和加热系统,可在一套设备内完成压滤脱水和热干化的过程,使污泥含水率从97%降至30%~40%。污泥在主机内完成传统板框压滤过程后,根据水沸点随压强减小而降低的原理,利用真空系统降低腔室内气压,使泥饼中水的沸点降低;同时采用热水作为供热介质加热污泥,使水分沸腾汽化并抽出。新塘污水处理厂处理规模为10×10~4m~3/d,设计最大湿泥量为400 m~3/d(含水率为97%),采用该工艺实现了污泥减量,出泥含水率降至40%以下。     

Effect of polyelectrolyte conditioning on the enhanced dewatering of activated sludge by application of an electric field during the expression phase

Activated sludge is known to be poorly dewaterable due to its high surface charge density and the extreme solids compressibility, even after polyelectrolyte conditioning. The application of an electric field during pressure dewatering (PDW) of sludge can enhance the dewaterability by the electroosmosis effect. A comparative study was conducted to investigate the additional effect of an electric field, applied during the expression phase, on the dewatering course of polyelectrolyte conditioned sludge, compared to mere PDW. It was found that the application of an electric field markedly improved the dewatering kinetics for all sludge samples, regardless of the conditioning treatment. Although the conditioning polyelectrolyte characteristics and dose had a major effect on the PDW of sludge, the conditioning history did not have a significant effect on the electroosmotic water transport efficiency during the sludge expression phase. By means of on-line streaming potential measurements and fractionated filtrate electrophoretic mobility measurements, it could be demonstrated that even at high polyelectrolyte doses, leading to positively charged sludge flocs, negative surface charges were still present inside the sludge matrix. During the expression of the sludge cake, when liquid is forced to move through the floc inside pores, these negative surface charges hampered PDW, but enhanced electroosmotic dewatering. Electroosmosis is therefore an appropriate technique to remove the water fraction that is associated with these negative surface charges.     

上海市竹园第二污水处理厂污泥脱水性能的研究

上海市竹园第二污水处理厂的泥饼含水率为78%左右,不能达到设计值(65%),为了分析其原因,对污泥的脱水性能进行了研究.结果表明,由于产生的剩余污泥脱水性能较差,且使用的是板框压滤机与PAM调理剂,使泥饼含水率降至65%是不可能实现的;根据该厂目前的运行状况及今后污泥的出路,泥饼含水率设定为75%左右较合理.     

壳聚糖与硅藻土调理市政污泥

以污泥比阻为评价指标,综合考虑脱水率、泥饼含水率及过滤时间因素,研究使用壳聚糖与硅藻土对污泥单独调理的最佳条件及联合调理改善污泥脱水性能的效果,并与聚丙烯酰胺调理污泥的效果进行了对比。结果表明,先投加0.5g/g硅藻土调理污泥,再投加5 mg/g壳聚糖以30r/min搅拌反应150s,污泥比阻下降了95.43%,脱水率上升至91.02%,泥饼含水率降至83.13%,过滤时间降至29.5s。壳聚糖与硅藻土联合调理的效果明显优于壳聚糖或硅藻土单独调理的效果,且其联合调理改善污泥脱水综合性能的效果优于聚丙烯酰胺调理污泥的效果。     

Pressurised electro-osmotic dewatering of activated and anaerobically digested sludges: electrical variables analysis

Pressurised electro-osmotic dewatering (PEOD) of two sewage sludges (activated and anaerobically digested) was studied under constant electric current (C.C.) and constant voltage (C.V.) with a laboratory chamber simulating closely an industrial filter. The influence of sludge characteristics, process parameters, and electrode/filter cloth position was investigated. The next parameters were tested: 40 and 80 A/m², 20, 30, and 50 V—for digested sludge dewatering; and 20, 40 and 80 A/m², 20, 30, and 50 V—for activated sludge dewatering. Effects of filter cloth electric resistance and initial cake thickness were also investigated.The application of PEOD provides a gain of 12 points of dry solids content for the digested sludge (47.0% w/w) and for the activated sludge (31.7% w/w). In PEOD processed at C.C. or at C.V., the dewatering flow rate was similar for the same electric field intensity. In C.C. mode, both the electric resistance of cake and voltage increase, causing a temperature rise by ohmic effect. In C.V. mode, a current intensity peak was observed in the earlier dewatering period. Applying at first a constant current and later on a constant voltage, permitted to have better control of ohmic heating effect. The dewatering rate was not significantly affected by the presence of filter cloth on electrodes, but the use of a thin filter cloth reduced remarkably the energy consumption compared to a thicker one: 69% of reduction energy input at 45% w/w of dry solids content. The reduction of the initial cake thickness is advantageous to increase the final dry solids content.     

粉煤灰调理自来水厂排泥水污泥的比阻

自来水厂污泥直排水体会使水环境恶化,为此开展了掺调理剂改善其脱水性能的试验研究。结果表明,自来水厂污泥不宜采用混凝处理,而利用电厂粉煤灰作调理剂,可使污泥比阻大幅度下降,改善了脱水性能;细粉煤灰的最佳投量是20g/100mL,粗粉煤灰的最佳投量是30g/100mL;粉煤灰与污泥混合形成的滤饼掺入一定比例的煤炭后可做成燃料,实现了自来水厂污泥的焚烧处置。     

螺旋压榨式脱水机对污泥脱水的试验研究

考察了螺旋压榨式脱水机对污泥的脱水性能.结果表明:对于含水率为97.9%的消化污泥,在絮凝剂投配率为0.51%、螺杆转速为0.25 r/min的条件下,脱水后泥饼含水率最低可达70.3%、固形物回收率为98.89%、污泥处理量为24.84 kg/h;对于含水率为99.7%的剩余污泥,在絮凝剂投配率为0.94%、螺杆转速为0.75 r/min的条件下,脱水后泥饼含水率为82.5%、固形物回收率为92.46%、污泥处理量为8.64 kg/h.螺旋压榨式脱水机对污泥的处理效果较带式脱水机有很大提高.     

硝酸钠强化污泥电渗透脱水的试验研究

在污泥中加入硝酸钠可提高电渗透脱水速率,考察了投药量、机械压力、电压和脱水时间等因素对电渗透脱水效果的影响。结果表明,在加入硝酸钠后,电渗透脱水速度加快、脱水程度增强、泥饼含固率在短时间内明显提高。分析认为,这主要和电渗透脱水过程中电流密度和温度的升高有关。在不同电压及脱水时间下,硝酸钠的加入更有效地提高了污泥含固率,且效果显著。     

三峡库区污水处理厂储泥池改造的思路和措施

对江津市几江污水处理厂污泥脱水过程中存在的问题进行了分析,提出了改造储泥池进泥方式的思路和措施.运行结果表明,该措施可大幅提高储泥池出泥浓度和降低污泥脱水过程中的电耗、絮凝剂耗量及泥饼含水率,节省运行费用.     

Compression dewatering of municipal activated sludge: effects of salt and pH

Even after mechanical dewatering, activated sludge contains a large amount of water. Due to its composition and biological nature this material is usually highly compressible and known to be difficult to dewater. In the present work, two treatments (salt addition and pH modification) are proposed to highlight some aspects which could explain the poor dewaterability of activated sludge. Dewatering tests are carried out in a pressure-driven device in order to well examine both, filtration and compression stages. Physico-chemical parameters, such as surface charge, hydrophobicity, extracellular polymeric substances (EPS) content and filtrate turbidity are measured on the tested sludge, for a better analysis of dewatering results.The dewatering ability of the sludge is widely linked to the cohesion of the flocculated matrix and the presence of fine particles. Both treatments alter the flocculated matrix and release fine particles. The release of fine particles tends to clog both, the filter cake and the filter medium. Consequently, the filtration rate decreases due to higher resistances to the flow. On another hand, the polymeric matrix breakdown enables to release some water trapped within the floc to the bulk liquid phase and thus facilitates its removal, which tends to decrease the moisture content of the filter-cake. It also impacts the compression dewatering step. The more destroyed structures lead to less elastic cakes and thus a slower primary consolidation stage. At the opposite, the mobility of the broken aggregates within the filter-cake does not seem to be improved by size reduction (the kinetics of the secondary consolidation stage are not significantly modified).