流化床富氧焚烧含油污泥技术经济性分析

介绍了流化床富氧焚烧含油污泥技术的流程和优势,计算了富氧焚烧含油污泥系统主要设备的电耗和技术经济指标。流化床富氧焚烧含油污泥技术可实现烟气及其他污染物零排放,产生的蒸汽可直接供应油田生产和生活使用,产生的液态CO2可直接用于油井驱油,烟气中的SO2和NOx可转化为硫酸和硝酸。采用日处理200 t含油污泥的流化床锅炉年处理含油污泥量约73 kt,每年减少排污费7 300万元;锅炉年产蒸汽量约177 kt,每年节约蒸汽费用1 380.6万元,合计每年节约成本8 680.6万元。回收得到质量分数为40%的稀硫酸5.56 t/d,质量分数为37%的硝酸0.708 t/d,年回收CO2约99 kt。     

UASB反应器反硝化处理工业废水

采用絮状污泥成功启动升流式厌氧污泥床(UASB)反应器处理含甲酸、苯胺、环已酮、NO3-等的工业废水。UASB反应器以低负荷启动,10天后逐渐提高进水COD,出水COD保持在710~770 mg/L,COD去除率为40%~60%;出水TOC保持在115~314 mg/L,TOC去除率由60.3%逐渐升高至87.2%,最终维持在81%左右;出水中ρ(NO3-)维持在134~176 mg/L,NO3-去除率为90%左右,系统稳定后NO3-去除率几乎为100%。在进水COD容积负荷不超过5.00 kg/(m3·d)的条件下,实际COD容积负荷稳定在2.00 kg/(m3·d)左右,实际TOC容积负荷稳定在1.00 kg/(m3·d)以上。当进水COD容积负荷不大于4.48 kg/(m3·d)时,COD去除率为55%~74%,TOC去除率为63%~87%,NO3-去除率大于95%。     

电镀污泥脱水稳定剂制备及应用研究

针对电镀污泥脱水过程中金属离子大量溶出带来的处理难题,以四甲基乙二胺、二硫化碳为主要原料,以氢氧化钾为引发剂,采用聚合法制备了一种脱水稳定剂,并考察了稳定剂投加量、污泥pH值、反应温度和反应时间对电镀污泥离心脱水时重金属溶出的影响。结果表明,在稳定剂投加量(稳定剂与污泥的质量比)为1%、反应温度为20℃、pH=1、反应时间为30 min、转速为3 000 r/min条件下对含Ni(Ⅱ)电镀污泥离心脱水后,Ni(Ⅱ)脱水稳定率达96.88%,且脱水稳定剂对混合电镀污泥中Ni(Ⅱ)、Cu(Ⅱ)的选择性大于Zn(Ⅱ)。脱水稳定剂的脱水稳定机理是其中的二硫代氨基甲酸盐与重金属离子M(Ⅱ)(Ni(Ⅱ)、Cu(Ⅱ)、Zn(Ⅱ)等)形成配位键,从而形成稳定的交联网状结构,达到化学稳定,实现了离心脱水极少重金属离子溶出(即脱水稳定)的效果。所合成的脱水稳定剂可广泛用于含镍、铜、锌等金属离子的电镀污泥脱水处理。     

印染污泥混燃特性及其燃烧动力学模型

采集了广东某印染污泥(YR)、造纸污泥(ZZ)及两种市政污水污泥(LJ、KFQ),利用热重法对不同来源污泥的单一及混合样在不同焚烧条件下进行了热重实验研究,并通过TG-DTG曲线计算了各试样的综合燃烧特性指数,获得了其燃烧动力学参数.结果表明,各单一试样的燃烧主要分为水分析出、挥发分析出、固定碳燃烧和残留物的燃烧和分解4个燃烧阶段,其中挥发分的析出制约着YR、KFQ、LJ污泥的整个燃烧过程,而ZZ污泥还受到固定碳燃烧阶段的显著影响.当向印染污泥中加入50%的KFQ市政污泥后,YR污泥的综合燃烧特性指数和可燃性指数分别提高了将近2倍和1.6倍.富氧(CO2/O2)燃烧可以提高印染污泥的后期燃烧强度,降低印染污泥燃烧阶段活化能,促进印染污泥的综合燃烧性能.采用积分法(Coats-Redfern方程)计算得到各燃烧阶段反应的机理方程及相应的活化能参数,发现第一挥发分峰前取反应级数n=0.5、峰后n=2,可描述各自阶段的燃烧反应机理,而第二挥发分峰没有显著规律.     

驯化活性污泥SBR工艺处理乳制品废水研究

乳制品废水直接采用生物法处理在现有研究中较少,为验证处理效果,将4阶段驯化后的活性污泥投加到SBR中,进行了低浓度乳制品废水的直接生物降解试验,主要考察了对COD、NH4-N的去除效果,结果显示:活性污泥驯化期间,COD、NH4-N平均去除率分别为93%、90%;驯化后的活性污泥处理效果稳定,当进水COD为1654 mg/L、NH4-N为115 mg/L时,出水COD、NH4-N分别为66 mg/L、2 mg/L,达到《污水综合排放标准》(GB 8978-1996)一级排放标准,证明了用驯化活性污泥直接处理低浓度乳制品废水是可行的.     

生活垃圾填埋场污泥塘处置方式探讨

目前国内许多生活垃圾填埋场接纳未达到入场技术要求的市政污泥,既要考虑尽量增加库容以满足填埋场使用年限的要求,又要对库区内现有的污泥塘进行处置以确保安全运行.文章以某填埋场污泥塘处置方案为例,探讨了针对污泥塘的加固措施,计算了加固前后垃圾堆体竖向位移、水平位移、不均匀沉降以及堆体边坡稳定系数等主要参数,设置加筋垫层一方面能提高地基承载力,另一方面减少了竖向和水平向位移和不均匀沉降,是处置污泥塘的有效措施.     

Bacterial communities in different locations, seasons and segments of a dairy wastewater treatment system consisting of six segments

A dairy wastewater treatment system composed of the 1st segment (no aeration) equipped with a facility for the destruction of milk fat particles, four successive aerobic treatment segments with activated sludge and a final sludge settlement segment was developed. The activated sludge is circulated through the six segments by settling sediments (activated sludge) in the 6th segment and sending the sediments beck to the 1st and 2nd segments. Microbiota was examined using samples from the non-aerated 1st and aerated 2nd segments obtained from two farms using the same system in summer or winter. Principal component analysis showed that the change in microbiota from the 1st to 2nd segments concomitant with effective wastewater treatment is affected by the concentrations of activated sludge and organic matter (biological oxygen demand [BOD]), and dissolved oxygen (DO) content. Microbiota from five segments (1st and four successive aerobic segments) in one location was also examined. Although the activated sludge is circulating throughout all the segments, microbiota fluctuation was observed. The observed successive changes in microbiota reflected the changes in the concentrations of organic matter and other physicochemical conditions (such as DO), suggesting that the microbiota is flexibly changeable depending on the environmental condition in the segments. The genera Dechloromonas, Zoogloea and Leptothrix are frequently observed in this wastewater treatment system throughout the analyses of microbiota in this study.     

Occurrence, distribution, and potential influencing factors of sewage sludge components derived from nine full-scale wastewater treatment plants of Beijing, China

Millions of tons of waste activated sludge (WAS) produced from biological wastewater treatment processes cause severe adverse environmental consequences. A better understanding of WAS composition is thus very critical for sustainable sludge management. In this work, the occurrence and distribution of several fundamental sludge constituents were explored in WAS samples from nine full-scale wastewater treatment plants (WWTPs) of Beijing, China. Among all the components investigated, active heterotrophic biomass was dominant in the samples (up to 9478 mg/L), followed by endogenous residues (6736 mg/L), extracellular polymeric substances (2088 mg/L), and intracellular storage products (464 mg/L) among others. Moreover, significant differences (p < 0.05) were observed in composition profiles of sludge samples among the studied WWTPs. To identify the potential parameters affecting the variable fractions of sludge components, wastewater source as well as design and operational parameters of WWTPs were studied using statistical methods. The findings indicated that the component fraction of sewage sludge depends more on wastewater treatment alternatives than on wastewater characteristics among other parameters. A principal component analysis was conducted, which further indicated that there was a greater proportion of residual inert biomass in the sludge produced by the combined system of the conventional anaerobic/anoxic/oxic process and a membrane bioreactor. Additionally, a much longer solids retention time was also found to influence the sludge composition and induce an increase in both endogenous inert residues and extracellular polymeric substances in the sludge.     

A new process to improve short-chain fatty acids and bio-methane generation from waste activated sludge

As an important intermediate product, short-chain fatty acids(SCFAs) can be generated after hydrolysis and acidification from waste activated sludge, and then can be transformed to methane during anaerobic digestion process. In order to obtain more SCFA and methane,most studies in literatures were centered on enhancing the hydrolysis of sludge anaerobic digestion which was proved as un-efficient. Though the alkaline pretreatment in our previous study increased both the hydrolysis and acidification processes, it had a vast chemical cost which was considered uneconomical. In this paper, a low energy consumption pretreatment method, i.e. enhanced the whole three stages of the anaerobic fermentation processes at the same time, was reported, by which hydrolysis and acidification were both enhanced, and the SCFA and methane generation can be significantly improved with a small quantity of chemical input. Firstly, the effect of different pretreated temperatures and pretreatment time on sludge hydrolyzation was compared. It was found that sludge pretreated at 100°C for 60 min can achieve the maximal hydrolyzation. Further, effects of different initial p Hs on acidification of the thermal pretreated sludge were investigated and the highest SCFA was observed at initial p H 9.0with fermentation time of 6 d, the production of which was 348.63 mg COD/g VSS(6.8 times higher than the blank test) and the acetic acid was dominant acid. Then, the mechanisms for this new pretreatment significantly improving SCFA production were discussed. Finally,the effect of this low energy consumption pretreatment on methane generation was investigated.     

Reversibility of the structure and dewaterability of anaerobic digested sludge

The reversibility of the structure and dewaterability of broken anaerobic digested sludge(ADS)is important to ensure the efficiency of sludge treatment or management processes.This study investigated the effect of continuous strong shear(CSS)and multipulse shear(MPS)on the zeta potential,size(median size,d_(50)),mass fractal dimension(D_F),and capillary suction time(CST)of ADS aggregates.Moreover,the self-regrowth(SR)of broken ADS aggregates during slow mixing was also analyzed.The results show that raw ADS with d_(50) of 56.5μm was insensitive to CSS–SR or MPS–SR,though the size slightly decreased after the breakage phase.For conditioned ADS with d_(50) larger than 600μm,the breakage in small-scale surface erosion changed to large-scale fragmentation as the CSS strength increased.In most cases,after CSS or MPS,the broken ADS had a relatively more compact structure than before and d_(50) is at least 200μm.The CST of the broken fragments from optimally dosed ADS increased,whereas that corresponding to overdosed ADS decreased.MPS treatment resulted in larger and more compact broken ADS fragments with a lower CST value than CSS.During the subsequent slow mixing,the broken ADS aggregates did not recover their charge,size,and dewaterability to the initial values before breakage.In addition,less than 15%self-regrowth in terms of percentage of the regrowth factor was observed in broken ADS after CSS at average velocity gradient no less than 1905.6 sec~(-1).