【作者】 王斌远；

【导师】 陈忠林；

【作者基本信息】 哈尔滨工业大学 ， 市政工程， 2014， 博士

【摘要】 随着工业的迅速发展，工业废水废渣对环境造成的污染日趋广泛和严重，威胁人类的健康和安全。由于行业类型繁多、生产工艺过程各不相同，工业废水具有污染物种类繁多、水质波动幅度大、污染物毒性强、排放量大等特点。因此，工业废水处理方法因废水类型和污染物种类不同而不尽相同，需要根据不同的水质确定最合适的工艺流程，以便得到最佳的处理效果。而工业废水处理过程中所产生的污泥成分复杂，处理难度极大，若得不到妥善处理，难免会对环境造成二次污染。因此，工业污泥的无害化、减量化、资源化，已受到广泛的关注。本文针对某工业园区所产生的含氟废水、含铬废水及含铬废渣处理过程中存在的实际问题进行针对性研究，提出可行的技术解决方案。针对现有钙盐混凝沉淀除氟工艺存在的处理效果不理想、石灰用量大以及污泥量大的问题，对钙盐混凝沉淀法除氟机理和工艺参数进行理论分析和实验室小试研究。水溶液中溶解性的氟离子浓度与溶液的pH值和Ca2+的浓度有关，钙盐混凝沉淀法处理含氟废水出水氟离子浓度高于理论计算值的主要原因是受石灰溶解度的限制以及共存阴阳离子的影响。利用加载絮凝工艺处理含氟废水进行中试研究，将沉淀的污泥进行部分回流作为絮凝载体，显著的提高了除氟效果，出水氟离子浓度随污泥回流比的增加而降低。将三氯化铁混凝剂和聚丙烯酰胺PAM助凝剂联合使用，能够显著提高对CaF2颗粒的混凝效果，三氯化铁最佳投量范围0.10⁰.20mmol/L，混凝过程中pH值最佳范围为8.0⁸.5，PAM最佳投量范围为1³mg/L。最佳工艺参数下进行运行试验，加载絮凝工艺对氟和浊度的去除率分别为96.31%、98.00%。化学还原沉淀法是含铬废水的常用处理工艺，对比考察了亚铁Fe（II）和亚硫酸盐S（IV）对六价铬Cr（VI）的氧化还原动力学，pH对氧化还原反应速率的影响，主要归因于对反应物和生成物的存在形态及氧化还原电位的影响，不同pH值下，不同形态的Cr（VI）和还原剂反应生成与pH值对应的生成物。Fe（II）还原Cr（VI）反应速率方程：-d[Cr（VI）]/dt=kobs[Cr（VI）][Fe（II）]，其中表观速率常数lgkobs为pH值的二次函数，满足lgk_obs=6.61-3.38pH+0.43pH2（1.5<pH<7.0），亚硫酸盐S（IV）还原Cr（VI）反应分别为Cr（VI）的一级反应，S（IV）的二级反应，反应速率方程如下：-d[Cr（VI）]t/dt=kobs[Cr（VI）]t[S（IV）]t2[H+]0.65，S（IV）还原Cr（VI）反应速率受反应体系pH值影响，表观速率常数与pH满足：lgk=-0.6466pH+6.1498（1.0<pH<5.0），pH值越低，反应速率越快。在酸性条件（pH<4）下，S（IV）还原Cr（VI）反应速率高于Fe（II），而中性和碱性条件下，使用Fe（II）还原Cr（VI）更有利。为了实现含铬废渣的无害化、减量化、资源化处置，降低和消除铬渣对水环境的二次污染，首先对铬渣的物理化学性质和酸浸出特性进行表征，含铬废渣具有强碱性，主要化学元素组成为CaO、MgO、Al2O3、Cr2O3、SiO2和Fe2O3，占总质量的90%以上。铬渣中总铬和Cr（VI）含量分别为2.28%、0.80%。铬渣中物相组成包括钙铁石（Ca2FeAlO5）、方镁石（MgO）、方解石（CaCO3）、白云石[CaMg（CO3）2]、水镁石[Mg（OH）2]、羟钙石[Ca（OH）2]和球霰石（CaCO3）。铬渣为具有浸出毒性的危险废物，有较大的酸中和能力，铬渣酸中和后pH值只与H+的投加量相关，无机酸阴离子种类对铬渣中总铬和六价铬的浸出产生影响，SO42-能将吸附于无定型金属氧化物上的CrO42-交换出来，增加了铬渣中铬的浸出量。对比考察了普通硅酸盐水泥、普通硅酸盐水泥掺加矿渣、普通硅酸盐水泥掺加粉煤灰、Ca（OH）2/矿渣、Na2SiO3/矿渣五种胶凝材料对铬渣的固定效果，结果表明：普通硅酸盐水泥对铬渣具有一定的固定效果，但对六价铬的固定主要为物理包裹，缺乏化学固定作用。普通硅酸盐水泥中掺入适量的矿渣可以显著的提高对铬的固定效果，矿渣替代普通硅酸盐水泥的最佳比例为45%。普通硅酸盐水泥中掺入粉煤灰对固化试件抗压强度和毒性浸出均产生不利影响。在对固化试件抗压强度要求不是很高的情况下，Ca（OH）2/矿渣为铬渣最佳固定材料，固化材料成本最低，且能满足较高铬渣掺量下具有较好的固定效果。Na2SiO39H2O/矿渣体系中Na2SiO39H2O配比的最佳范围为15%²5%，当铬渣掺量小于35%时，固化试件抗压强度较高且毒性浸出浓度非常低。铬渣掺量应控制在35%以内。利用Fe（II）湿法还原和Ca（OH）2/矿渣体系稳定固定化铬渣，经过Fe（II）还原后固化体固化效果显著提高，毒性浸出实验总铬浓度较单纯固定时大幅降低，六价铬均未检出。利用实验优化参数对工业园区废水处理工艺进行改造，改造后运行稳定，处理效果远优于原有常规处理工艺，总排放口各主要污染物指标均满足《污水综合排放标准》（GB8978-1996）一级标准，而且废水处理污泥产量大幅度降低，平均污泥产率比改造前常规工艺降低了39.6%，每吨废水处理运行成本降低了0.71元。最后，对工业园区废渣及污泥处理提出了可行的技术方案，采用稳定固定化方法处理具有良好的环保效益和经济效益。更多还原

【Abstract】 With the rapid development of industry, environmental pollution caused by industrial wastewater and waste sludge has gradually become widespread and severe, threatening human health and safety. Due to various industry types and different manufacturing technological processes, the pollutant varieties of industrial wastewater are numerous, the water quality fluctuation range is large, the pollutant toxicity is strong and the discharge is huge. Therefore, the industrial wastewater treatment methods differ a lot according to different wastewater types and pollutant varieties and according to different water qualities, the most proper technological process shall be determined to obtain optimal treatment effect. However, the sludge components in the industrial wastewater treatment process are complex and the treatment difficulty is extremely huge. If they are not properly treated, it is easy to lead to secondary pollution of the environment. Therefore, the hazard-free treatment, reduction and reclamation of industrial sludge have been paid wide attention to. Specific to the practical problems of fluoride-containing wastewater, chromium-containing wastewater and chromium-containing waste residue in the treatment process in one industrial park, this paper put forward feasible technical solutions.Specific to the unsatisfactory treatment effect of defluorination using coagulation sedimentation by calcium salt, huge quantity of lime and large sludge quantity, theoretical analysis and laboratory bench-scale study were conducted on defluorination mechanism by calcium salt coagulation sedimentation and technological parameters. The concentration of soluble fluorine ion in aqueous solution was related to the pH value of solution and the concentrations of Ca2+. The concentration of effluent fluoride in fluoride-containing wastewater by calcium salt coagulation sedimentation was higher than the theoretical value. The major reason for this is the limits of lime solubility and the influence of coexistence of anion and cation. Ballasted flocculation process was utilized to treat fluoride-containing wastewater for pilot-scale study. Part of the precipitated sludge was recycled as flocculation carrier, which significantly improved the defluorination effect and the concentration of effluent fluorine ion decreased with the increase of sludge recycle ratio. Ferric chloride coagulant and PAM coagulant aids were jointly used, which could significantly improve the coagulation effect of CaF2particle. The optimal volume of ferric chloride ranged from0.10to0.20mmol/L, the optimal pH in the coagulation process ranged from8.0to8.5, and the optimal volume of PAM ranged from1to3mg/L. Under the optimal technological parameters, operation test was carried out and the mean defluorination and turbidity removal rate by ballasted flocculation process respectively were96.31%and98.00%.Chemical reduction precipitation method is a common treatment process of chromium-containing wastewater. This paper compared and investigated the influence of oxidation-reduction dynamics of Fe（II） and S（IV） on Cr（VI） as well as the influence of pH on oxidation-reduction reaction rate, mainly due to the influence of existing forms of reactants and products and oxidation-reduction potential, Cr（VI） of different pH values and forms and the reductant reaction product and the corresponding product of pH after the reaction. The reaction rate equation of Fe（II） on Cr（VI） is-d[Cr（VI）]/dt=kobs[Cr（VI）][Fe（II）], where apparent rate constantlgkobsis quadratic function of pH, satisfying lgk_obs=6.61-3.38pH+0.43pH2（1.5<pH<7.0）. The reduction reaction of S（IV） on Cr（VI） respectively was the first-order reaction of Cr（VI） and the second-order reaction of S（IV）. The reaction rate equation was as follows,-d[Cr（VI）]/dt=k_obs[Cr(VI_tS（IV）]_t²[H+]_t^0.65. The reaction rate of S（IV） on Cr（VI） is influenced by the pH of reaction system. The correlation between apparent rate constant and pH satisfiedlgk=-0.6466pH+6.1498（1.0<pH<5.0）. The lower the pH value was, the faster the reaction rate was. Under acidic condition （pH<4）, the reduction reaction of S（IV） on Cr（VI） was higher than Fe（II）; while under neutral and alkaline conditions, the reduction reaction of Fe（II） on Cr（VI） was better.Representation was made on the physicochemical property and acid leaching characteristics of chromium-containing waste slag and it showed a strong alkalinity. The major chemical elements included CaO, MgO, Al2O3, Cr2O3, SiO2and Fe2O3, accounting for over90%of the total mass. The contents of total Cr and Cr（VI） in COPR respectively were2.28%,0.80%. The phase composition of chromium-containing slag included Ca2FeAlO5, MgO, CaCO3, CaMg（CO3）2, Mg（OH）2, Ca（OH）2and CaCO3. chromium-containing slag was dangerous waste with leaching toxicity and owned great acid neutralization capacity. After acid neutralization of chromium-containing slag, pH was only relevant to the dosage of H+and the variety of inorganic acid anion had influences on the leaching of total Cr and Cr（VI） in chromium-containing slag. SO42-can replace CrO42-on metallic oxide in amorphous form, which could increase the leaching amount of Cr in chromium-containing slag.This paper compared and investigated the solidification effects of ordinary Portland cement, ordinary Portland cement with slag, ordinary Portland cement with fly ash, Ca（OH）2/slag and Na2SiO3/slag on chromium-containing slag. However, the solidification of Cr（VI） mainly was physical wrapping while lacked chemical fixation mechanism. Properly-adding slag in ordinary Portland cement could significantly improve Cr fixation effect and the optimal ratio of slag to ordinary Portland cement was45%. Adding fly ash in ordinary Portland cement could have adverse effects on the compressive strength and toxicity leaching of the solidification specimen. Under the low requirement of the compressive strength of the solidification specimen, Ca（OH）2/slag was the optimal fixation material of chromium-containing slag, which owned the lowest cost and could achieve better fixation effect under high dosage of chromium-containing slag. In the system of Na2SiO39H2O/slag, the optimal ratio of Na2SiO39H2O fell between15%²5%. When the dosage of chromium-containing slag was less than35%, the compressive strength of the solidification specimen was high and the concentration of toxicity leaching was extremely low. The dosage of chromium-containing slag shall be limited within35%. Fe（II） hydrometallurgical reduction and Ca（OH）2/slag system were used to stabilize and fix chromium-containing slag. After the reduction of Fe（II）, the fixation effect of solidified specimen was improved significantly and the total Cr concentration in the toxicity leaching experiment decreased greatly compared with pure fixation and no Cr（VI） were detected.The transformation of wastewater treatment process in the industrial park was conducted according to the optimized experimental parameters. A more stable and better operational results were obtained compared with the original process. The effluent quality could meet the first grade nationnal discharge standard―integrated wastewater discharge standard‖（GB8978-1996）. The sludge yield significantly reduced with the average sludge production ratio decreased by39.6%. Moreover, the operating costs per ton of wastewater reduced0.71yuan. Finally, a feasible technical treatment solution for residues and sludge in the industrial park was proposed and also a good environmental and economic benefits were gained by immobilized disposition.更多还原