强化化学淋滤对污泥重金属溶出及磷释放的影响

针对采用传统化学淋滤方法处理污水污泥时重金属溶出率低的问题,设计了两种强化化学淋滤方法的对比试验,通过检测重金属形态分布、污泥有机质及磷释放、污泥含固率,研究了强化化学淋滤对污泥各方面综合性能的影响。结果表明:稀硫酸与氯化铁联合处理(处理方法1)对Cu和Cr的溶出效果不明显,但在加入NaNO₂(处理方法2)后使Cu溶出率由7%提升至82%,Zn溶出率由79%提升至88%;同时,两种强化化学淋滤方法均增加了污泥中有机质和磷的释放,污泥中磷含量由23.2 mg/g分别降至12.3 mg/g和10.7 mg/g;与原污泥相比,强化淋滤后的污泥脱水性也均得到了明显改善,其污泥含固率分别提高了52%和61%。     

剩余污泥热处理过程中磷、氮和有机碳的释放特性

采用热处理方法可以使剩余污泥中的磷快速释放出来,从而为进一步的磷回收创造有利条件。为了能更全面地了解热处理过程,通过与生物释磷过程进行比较,考察了剩余污泥热处理过程中磷、氮和有机碳的释放特性。试验结果表明,最佳的热处理参数是:热处理温度为50℃,处理时间为1 h,此时的净释磷浓度和释磷速率分别可达81.8 mg/L和9.98 mgPO43--P/(gMLSS.h),分别为生物释磷的3.7倍和2.6倍,而氮和有机碳的释放量较少,有利于磷的回收。     

水泥固化污泥中重金属的浸出试验研究

通过对不同掺量比例的电镀污泥和生活污泥砂浆试样的重金属浸出试验,研究了水泥固化作用对污泥中重金属浸出的影响。研究结果表明,重金属浸出浓度随着污泥掺量比例的提高而增大;不考虑物理稀释作用,同种类污泥的砂浆试样的重金属浸出浓度比较接近;随着养护龄期的延长,重金属浸出浓度呈降低趋势。     

超声强化污泥释磷及MAP法磷回收优化研究

为提高剩余污泥的磷释放与回收效果,采用超声强化EDTA-厌氧处理后的剩余污泥释磷,并以鸟粪石(MAP)结晶法回收上清液中的磷,探究超声对磷释放的影响,同时确定了最佳超声工作参数,采用响应曲面法构建MAP法磷回收的二次多项式模型并验证了模型的适用性。结果表明,超声可以强化污泥中磷的释放,最佳超声工作参数如下:声能密度为1.0 W/m L、超声时间为40 min,在最佳工作参数下可向液相释放60%的TP,TP、PO34--P浓度分别达到未超声处理的1.6倍和1.4倍;经超声后污泥上清液中TP增加量与MLSS、MLVSS减少量呈正相关关系,每溶解1 mg的MLSS向上清液中释放0.010 1 mg的TP;磷回收的最优工艺条件:nMg/nP=2、pH值=9、搅拌时间为21 min,此时磷回收率为89.29%,回收的晶体产物主要成分是磷酸铵镁,其纯度为77.56%,且相比未超声,该条件下的回收量提高了30%。     

差异含水率条件下飞灰及其螯合物的应力应变及环境特性

垃圾焚烧飞灰因极高的重金属含量而被认为是一种危险废弃物,但与火山灰成分的相似使该材料有着资源化利用的潜在价值。以飞灰及其螯合物为研究对象,探讨了含水率、养护条件等因素对材料应力应变及环境特性的影响。研究结果表明:飞灰螯合物重金属浸出浓度较低,并有着较强的吸水特性;飞灰及其螯合物强度早期随着养护时间的增长呈上升趋势,破坏应变随之减小,脆性不断增大;材料强度在中后期出现明显分化,飞灰(90%湿度养护)强度约为螯合飞灰的23.11倍。飞灰强度随含水率的增大而减小,可归结于孔隙水对压实能量的吸收和结构的影响;螯合飞灰强度均随养护时间和含水率增加而显著增大。     

水泥协同垃圾焚烧飞灰固化渗滤液污泥试验研究

采用硫铝酸盐水泥协同生活垃圾焚烧飞灰作为胶凝材料对渗滤液污泥进行固化,通过无侧限抗压强度试验、浸出毒性分析和微观测试,探索水泥与飞灰的复合固化效果和固化机理.结果表明：当水泥掺量不小于20%时,固化试样的28 d无侧限抗压强度满足填埋强度要求;飞灰是水泥固化渗滤液污泥的优良辅助固化剂,其对水泥固化试样无侧限抗压强度的增强效应存在最优掺量;10%的飞灰可替代10%的水泥而使固化试样达到更好的固化效果;复掺30%或40%水泥+15%飞灰的试样可同时满足填埋强度和浸出毒性的要求.     

城市生活垃圾焚烧底灰的水热固化研究

利用水热技术对城市生活垃圾底灰进行资源化利用研究,将其固化为一种强度高、重金属溶出少的建筑材料.主要研究了添加消石灰固化生活垃圾底灰的硬化机理,并且为了100%利用垃圾焚烧灰,也研究了添加垃圾飞灰固化底灰的方法.同时还进行了重金属浸出试验,测试固化体中重金属溶出量.研究结果表明,托勃莫来石晶体的生成是影响固化体强度的主要原因,而且托勃莫来石的生成量越多,样品的强度越高.飞灰也可以作为一种固化添加剂对底灰进行水热固化,且添加飞灰的硬化机理和消石灰相同.经过水热固化,固化体的重金属溶出量可大大降低.水热技术有望成为一种城市生活垃圾底灰资源化利用的有效方法.     

污泥减量化工艺:HA-A/A-MCO的除磷性能及磷回收

针对污泥减量技术中对氮、磷去除能力低的问题,开发了一种具有强化脱氮除磷功能、污泥减量化的HA-A/A-MCO工艺,其通过回流释磷污泥的水解酸化来刺激磷的厌氧释放并辅以外排富磷污水进行化学固定的方式除磷.研究发现:当进入水解酸化池的厌氧释磷污泥量为进水量的2%时,水解产生的VFA导致释磷量达57 mg/L,聚磷菌的生长得到促进而聚糖菌则受到抑制;当控制侧流除磷液量为进水量的13%、化学除磷池出水磷为5 mg/L时,系统处理出水TP<0.5 mg/L;提高厌氧释磷浓度并控制化学除磷池的出水磷浓度为5 mg/L,可以提高化学药剂利用率、减少药剂用量并提高化学污泥的含磷量,HA-A/A-MCO系统产生的化学污泥含磷率高达18%,接近纯含磷化合物的含磷率,可直接用作生产磷肥的原料.     

污泥焚烧灰渣无害化处理及其资源化利用技术研究

污水厂污泥焚烧是一种有效的减量化处理方式,焚烧产生的污泥焚烧灰渣通常被运到填埋场进行填埋处置.根据污泥灰渣的物理特性,对其进行了急性毒性分析和水化活性分析,并经过无害化处理的污泥焚烧灰渣寻找到了使其资源化利用的新方法,即固化后制成的路基材料.用该法制成的路基材料抗压强度满足规定的技术要求,同时,重金属浸出毒性也满足国家固体废物排放标准的要求.     

The feasibility of coagulant recycling by alkaline reaction of aluminium hydroxide sludges

Coagulant recycling appears to be economically attractive as much by the reduction of fresh chemical dosing as by the simplification of the sludge disposal. The present paper has studied the feasibility of aluminium coagulant recovery by an alkaline treatment of sludge. The study was carried out on sludge obtained from the drinking-water treatment plant of the Brussels' Intercommunal Waterboard located at Tailfer on the river Meuse. The general conditions are summarized as follows and given as guidelines:

&#x02022; to limit the starting sludge concentration to a threshold below 20 g l⁻¹ dry wt concentration;

&#x02022; to optimize the alkalisation process which means a pH between 11.4–11.8 for NaOH and 11.2–11.6 for Ca(OH)₂;

&#x02022; to choose between NaOH and Ca(OH)₂ is optional but heavy metals contained in the sludge are reduced by a factor of 10–15 by using lime instead of NaOH;

&#x02022; to use a settling process to recover the supernant before recycling and therefore best limit the recovery to 25–30% of the coagulant even though when using sodium hydroxide, an 80% recovery is possible.

When restricting the recycling to less than 50% of the coagulant (for instance 25–30%) no detrimental effect on the treatment performance was detected in conditions of this laboratory investigation.     

城市污泥热干化产品林地施肥试验

采用重庆市鸡冠石污水处理厂的干化污泥产品进行林地施肥试验,观测了树径的增长及土壤中重金属的累积情况。结果表明,干化污泥中含有丰富的N、P、K养分,施用干化污泥产品能够促进植物生长,且土壤中重金属累积作用不显著,重金属污染风险较低。     

电动力修复技术去除城市污泥中的重金属研究

分析了城市污水处理厂污泥中重金属的形态，重点考察了不同形态的Cd、Zn在电动力作用下的去除率。结果表明，污泥经电动力作用5d后，对Cd、Zn的总去除率分别为64．50％、65．02％，其中对易被植物吸收的非稳态（可交换态、碳酸盐结合态和铁锰氧化物结合态）Cd、Zn的去除效果尤为明显，去除率分别高达68．60％、75．73％。可见，应用电动力修复技术去除污泥中的重金属是可行的，修复后的污泥可进行土地利用。     

污泥减量HA-A/A-MCO工艺的除磷特性

针对国内外开发的大多数污泥减量技术都存在着脱氮除磷效率低下的难题,研发了一种具有提高除磷脱氮效能的污泥减量新工艺——HA-A/A-MCO工艺,采用水解酸化污水与释磷污泥的混合液刺激磷的厌氧释放并辅以外排富磷污水进行化学固定的方式除磷,通过试验研究,得出了一些有价值的结论。     

污泥堆肥化对重金属生物可利用性的影响

通过重金属形态分析及在模拟雨水、酸雨淋溶条件下重金属迁移实验和理论分析,研究了堆肥化处理对污泥中重金属生物可利用性的影响。结果表明：堆肥化处理使重金属的不稳定形态含量降低,原污泥在酸雨淋溶下重金属已经迁移到约16厘米深的土柱中,而经过处理后的污泥淋出液中的重金属含量很低,仅有少量污泥中含量较高的元素向土柱深层迁移。迁移量及深度明显低于未处理的原污泥。实验及理论分析均证明了堆肥化处理可以降低污泥中重金属在土壤中的迁移性,使重金属的生物可利用性降低。     

污泥焚烧灰分磷回收潜力分析及其市场前景

磷资源不可替代又不能再生。现代工业攫取磷矿大多用于磷肥生产,通过作物收获的粮食、蔬菜以及饲养畜禽肉类进入人体,而随食物进入人体的大多数磷(90%)会随排泄物进入污水(无粪尿返田情况)。尽管最终进入污水中的磷占开采磷矿的比例很小(<5%),但这是人类除动物粪便与作物秸秆外唯一可能实现磷人工循环的位点,相对于转移进作物中的磷来说该比例超过1/4。因此,在废弃粪尿返田之原生态习惯的情况下,从污水处理过程中回收磷则显得非常重要。目前从污水处理过程中回收磷存在许多方式与产品,而与污泥焚烧灰分相关的磷回收程度最高,可达90%。为此,首先基于全球磷资源危机与我国磷流向及其估算,揭示磷回收的必要性和急迫性。然后,对与污泥焚烧相关的灰分磷回收技术以及潜在应用进行总结和分析。最后,根据肥效实验与成本估算,认定灰分再生磷肥比传统矿石磷肥具有潜在市场前景,特别是它的可持续意义。     

The adsorption of heavy metals in an acidogenic thermophilic anaerobic reactor

A two-phase, thermophilic anaerobic reactor was operated with a starch-based feed. Copper, zinc, nickel and lead (3 mM) were individually added to the feed each for a period of 30 h. The results were analysed to determine the extent of metal binding in the acidogenic, first-stage reactor and the degree of protection that this afforded to the traditionally more sensitive methanogenic phase. The results showed that zinc and nickel were not bound particularly well, that lead was bound very strongly and that copper had binding characteristics that were between these two extremes. When these findings were compared with an earlier study with a mesophilic sludge, zinc was shown to have a very different behaviour. A possible reason for this is given. An examination of the gas production by the methanogenic stage, in relation to the amount of metal reaching this stage, suggested that the phase separation did not offer any real protection from the toxic effects of heavy metals.     

pH对剩余污泥中氮、磷释放的影响

将pH分别控制在不同条件下(3.0、5.0、8.0、10.0和不调节),并测定各条件下剩余污泥溶出的NH4+-N和PO34--P浓度,考察了剩余污泥在水解酸化过程中pH对NH4+-N、PO43--P释放的影响。结果表明:对剩余污泥的pH进行调节,能够提高氨氮、正磷酸盐的释放量,且酸性环境下的NH4+-N和PO43--P释放量明显高于中性和碱性环境下的释放量。     

Sludge dewatering in a conventional plant with phosphorus removal-II: Study on centrifuge and filter-press performance

Dewatering tests were carried out at the Cesenatico sewage treatment plant to point out the influence of phosphorus removal on sludge characteristics, using either aluminium or ferrous sulphate. Equipment performance was studied in different conditions to determine the influence of machine operational variables.As far as centrifugation is concerned, the results showed that the most significant variables the dewatered sludge concentration depends on are the beach residence time and liquid ring height. The feed sludge concentration proved a significant variable if all the data obtained in the three phases are considered together. A pressure filtration model for the prediction of final cake concentration was set up based on the correlations of coefficients a and b of the filtrate flow curve (φ = a·t^b) with sludge characteristics (concentration, specific resistance to filtration) and with maximum operating pressure.     

Sludge dewatering in a conventional plant with phosphorus removal-I: Analysis of additional costs

The aim of this research is to assess the differences in quantity and quality of sludges produced in a conventional activated sludge plant, modified for phosphorus chemical removal. Tests were carried out at the Cesenatico sewage treatment plant, where in summer phosphorus is removed simultaneously to the biological process with the aid of aluminium or ferrous sulphate. Characteristics of the sludge produced with or without phosphorus removal were compared. The sludge was then dewatered by a centrifuge and a filter-press on pilot scale and many tests were carried out under different operating conditions.In this part, the plant's most important performances are discussed with regard to phosphorus removal efficiency, sludge production, characteristics and dewaterability. The experiments showed that phosphorus could be removed up to residual concentration of 1.6 mg 1^?1 without detrimental effects on the biological process, with an increase of sludge production of 21 and 36% using aluminium or ferrous sulphate respectively. On the basis of experimental results a costs analysis was carried out to assess the costs for phosphorus removal, including the additional ones for sludge conditioning, dewatering and cake transport to landfill. It results that additional costs vary from 3290 to 6380 Lit per capita per year (29–54%). The higher costs refer to smaller plants (50,000 inhabitants), in which aluminium sulphate is used and sludge dewatered by centrifuge. The use of ferrous rather than aluminium sulphate allows savings of 1300–1600 Lit per capita per year.     

On wet chemical phosphorus recovery from sewage sludge ash by acidic or alkaline leaching and an optimized combination of both

The advantages and drawbacks of existing wet chemical phosphorus (P) recovery technologies, their applicability to different types of sewage sludge ash (SSA) and the role of the decay products of detergent zeolites as a source of reactive Al in SSA are analyzed. Since neither a purely acidic nor a purely alkaline treatment are able to provide satisfactory technical solutions a wet chemical phosphorus (P) recovery process for sewage sludge ashes (SSAs) is investigated in detail that is based on a sequential treatment of SSA with an acid and a base. As a result of an acidic pre-treatment, the P fraction of the raw SSA that was bound as - alkaline-insoluble - calcium phosphate (Ca-P) is converted into aluminum phosphate (Al-P). This newly formed Al-P can be easily dissolved via alkaline treatment and then easily separated from the alkaline leachate via precipitation of Ca-P. The Al-component can be reused as precipitant for P-removal in waste water treatment plants (WWTPs). The investigated process requires fewer chemicals than the direct acidic dissolution of all P-compounds contained in the SSA. This is due to the described rearrangement of the P component from Ca-P to Al-P. That such a rearrangement of P occurs indeed was confirmed through a combination of XRD, ICP and XRF analyses together with mass balance calculations. The present investigation proves that the process works for very different types of SSAs: For Al-rich SSAs that come from WWTPs where Al-salt is used for chemical P-removal the described sequential treatment process works best and yields P-recovery rates as high as 70-77%. But even for SSAs from WWTPs where only iron salt is used for chemical P-removal, a considerable amount of the reactive Al necessary for the described P-rearrangement is supplied by decay products of detergent zeolites, a hidden Al-source present in most SSAs produced in Europe.