Effect of proteins, polysaccharides, and particle sizes on sludge dewaterability

Four batch experiments of hydrolysis and acidification were carried out to investigate the distributions of proteins (PN) and polysaccharides (PS) in the sludge, the PN/PS ratio, the particle sizes, and their relationship with sludge dewaterability (as determined by capillary suction time, CST). The sludge flocs were stratified through centrifugation- and ultrasound-based method into four fractions: (1) slime, (2) loosely bound extracellular polymeric substances (LB-EPS), (3) tightly bound EPS (TB-EPS), and (4) pellet. The results showed that PN was mainly partitioned in the pellet (80.7%) and TB-EPS (9.6%) fractions, while PS distributed evenly in the four fractions. During hydrolysis and acidification, PN was transferred from the pellet and TB-EPS fractions to the slime fraction, but PS had no significant transfer trends. The mean particle sizes of the sludge flocs decreased with hydrolysis and acidification. The pH had a more significant influence on the dewaterability of sludge flocs than temperature. Sludge dewaterability during hydrolysis and acidification processes greatly deteriorated from 9.7 s at raw sludge to 340–450 s under alkaline conditions. However, it was just slightly increased under acidic conditions. Further investigation suggested that CST was a ected by soluble PN, soluble PN/PS, and particle sizes of sludge flocs, but was a ected slightly by total PN, PS, or PN/PS in the whole sludge flocs and other fractions (except slime).     

Emission characteristics of dioxins, furans and polycyclic aromatic hydrocarbons during fluidized-bed combustion of sewage sludge

Pre-dried sewage sludge with high sulfur content was combusted in an electrically heated lab-scale fluidized-bed incinerator. The emission characteristics of polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and polycyclic aromatic hydrocarbons (PAHs) were studied. Coal and calcium oxide (CaO) were added during the sewage sludge combustion tests to optimize combustion conditions and control SO2 emission. The results indicated that the flue gases emitted during mono-combustion of sewage sludge were characterized by relatively high concentrations of SO2, NOx and organic pollutants, due to the high sulfur, nitrogen, and volatile matter content of sewage sludge. The total 16 USEPA priority PAHs and 2,3,7,8-substituted PCDD/Fs produced from sewage sludge combustion were found to be 106.14 g/m3 and 8955.93 pg/m3 in the flue gas, respectively. In the case of cocombustion with coal (msludge/mcoal = 1:1), the 16 PAHs and 2,3,7,8-substituted PCDD/Fs concentrations were markedly lower than those found during mono-combustion of sewage sludge. During co-combustion, a suppressant e ect of CaO on PCDD/Fs formation was observed.     

太阳能技术在住宅建筑中的应用

太阳能技术的应用对我国住宅产业的发展具有重要意义。文章分析了目前国际和国内住宅建设领域中太阳能技术的应用形式与局限,指出了我国实现太阳能住宅建筑一体化进程中应着重解决的主要问题。     

曝气生物滤池处理生活污水的试验研究

采用曝气/间歇曝气生物滤池处理生活污水的动态模拟方法,考察了该种形式的曝气生物滤池在不同的间歇时间下对COD去除效果的影响。     

超临界水氧化技术在污水处理中的应用

介绍了超临界水氧化的反应机理、工艺流程及其在污水处理领域的应用现状、突出优点,同时指出了这种新型污水处理技术存在的问题和发展方向。     

磷酸铵镁沉淀法脱除生活污水中氮磷的研究

针对低有机物高氨氮浓度的生活污水,经UASB处理后的厌氧废水,氮含量较高,磷基本未除去,处理出水效果欠佳的情况,提出磷酸铵铗沉淀法脱除生活污水中的磷以及部分氨氮。初步确定了影响磷酸铵镁沉淀反应因素为pH值,Mg^2＋：PO4^3-：NH4^＋,反应时间t。最优反应条件为：pH=8．5,Mg^2＋：PO4^3-：NH4^＋=1．2：1：1,反应时间t=1min。磷的去除率可高达94．0％,氨氮的去除率达71．5％,为低浓度的生活污水的后续生物处理创造了良好的条件。     

污泥屏障氧化缓冲容量与重金属再溶出关系研究

借助微生物厌氧活动特别是硫酸盐还原反应,污泥屏障可用来固定尾矿堆场重金属.针对尾矿风化淋滤形成的酸性采矿废水(AMD)与污泥之间发生的氧化还原反应导致的重金属溶出问题,通过氧化滴定实验研究了不同污泥悬液的氧化缓冲容量及其与重金属浓度的关系.结果表明,污泥悬液的氧化缓冲容量随着悬液固液比的增大略有减小,但随着悬液厌氧培养时间的延长而增加.污泥的氧化缓冲容量主要来自Eh≤-150mV的强烈还原区间,可达氧化缓冲容量的50%以上.氧化滴定过程中发现,当Eh≥-150mV时,Zn首先明显溶出;当Eh≥150mV时,Cu和Pb明显溶出.基于实验结果,建立了污泥屏障在AMD渗流条件下氧化缓冲容量消耗的数学模型.模拟计算结果表明,当AMD水头高度为10m时,厚度2m的污泥屏障经历AMD溶液38787a的渗透氧化,仍可保持原有的强烈还原状态,具备对重金属的固定效果.     

酸缓冲容量对污泥屏障重金属再溶出控制研究

借助污泥中的厌氧微生物活动,污泥屏障可用来固定尾矿堆场的重金属.针对尾矿风化淋滤形成的酸性采矿废水(acidmine drainage,AMD)与污泥屏障相互作用,可能会引起已固定重金属再次溶出问题,通过酸滴定实验,研究了不同厌氧培养时间的污泥悬液的酸缓冲容量及其对重金属再溶出的影响.结果表明,污泥悬液酸缓冲容量与悬液固液比成正比,并随着厌氧还原程度的加深而增加.碳酸盐缓冲体系和有机质缓冲体系对污泥悬液酸缓冲有重要意义.酸滴定实验发现,随着pH降至6.2以下,重金属Zn、Pb和Cu开始快速溶解释放,且释放量符合ZnCuPb.基于实验结果,建立了污泥屏障在AMD渗透条件下酸缓冲容量消耗的数学模型.模拟计算结果表明,对于厚度2.0 m的污泥屏障,即使在10.0 m水头的AMD渗透酸化条件下,有效酸缓冲容量经历666 a之后才能被耗尽,在此时间内污泥屏障具备对重金属的生物化学固定能力.     

超声波-缺氧/好氧消化过程污泥EPS、酶活性及菌落数的变化研究

为研究超声波促进污泥缺氧/好氧消化的机理,采用最佳超声波参数（超声频率28kHz,超声密度0.1W.mL-1,超声时间15min,超声间隔时间12h）与缺氧/好氧消化衔接进行间歇试验,研究了消化过程中污泥胞外聚合物（EPS）组分（蛋白质、多糖、DNA）和相应溶出物占总量的比例,以及酶活性（蛋白酶,脱氢酶）和菌落数的变化...     

小型垃圾转运站渗滤液特性及其对城市水环境的影响

对两个城市的小型垃圾转运站现状进行了分析,并对其渗滤液产生量及渗滤液性质进行了监测。结果表明:小型垃圾转运站转运量小、分布密集;深圳垃圾转运站产生的混合污水并入城市污水管网,常州的小型垃圾转运站,产生的渗滤液及冲洗废水50%直接排入了河道;转运站排放的混合污水,除汞外,其他指标远超GB 8978-1996《污水综合排放标准》及CJ 3082-1999《污水排入城市下水道水质标准》,小型垃圾转运站排放的污染物中,以COD负荷最高,其次是BOD5。大量的有机物排入城市污水厂,对污水厂的正常运行造成冲击,如果直接排入水体,更加速了水体的污染,因此,常州市城市排水系统优化改造及垃圾转运站的截污、治理势在必行。