Purification performance of biogas slurry by blended CaO/PAC flocculant

doi:10.16085/j.issn.1000-6613.2017-1760

Abstract

Abstract: Biogas slurry generating from the biogas anaerobic fermentation project contains a substantial amount of organic pollutants. It should be treated properly to meet the requirements of the discharge standard or farmland irrigation standard. In order to reduce the operation cost of biogas slurry purification,biogas slurry should be pretreated firstly to reduce all the turbidity value,chemical oxygen demand(COD)and the concentration of total phosphorus(TP),and increase the removal potential of ammonium nitrogen as well. A blended flocculant prepared with calcium oxide(CaO)and polyaluminum chloride(PAC),CaO/PAC,was added into biogas slurry to fulfill this target in the study. It should be noted that the removal potential of ammonium nitrogen was represented by pH of biogas slurry in the study because of the positive correlation between pH and the free ammonia concentration determining the ammonium nitrogen removal performance directly. In terms of turbidity,COD,TP content and pH,the addition order of CaO and PAC in CaO/PAC flocculant,the ratio of CaO mass to PAC mass(m_CaO/m_PAC),and the total concentration of CaO/PAC were investigated. Results showed that the effect of the addition order of CaO and PAC on biogas slurry purification performance is insignificant. With the decrease of m_CaO/m_PAC value and the increase of the total concentration of CaO/PAC flocculant,all the turbidity value,COD and TP contents decrease accordingly. However,the removal potential of ammonium nitrogen in biogas slurry improves with both the m_CaO/m_PAC value and the total concentration of CaO/PAC. If a good biogas slurry pretreatment performance was targeted,it should be better to determine the total concentration of CaO/PAC at 12.5-18.75g/L,and fix m_CaO/m_PAC value at (2-10):1.

Key words: waste water, biogas slurry, ammonium nitrogen removal, flocculant, coagulation, environment

摘要： 厌氧发酵后产生的沼液中含有大量的有机污染物需要处理，为降低后期沼液处理工程的操作费用，改善常规絮凝剂存在的不足，本文提出向沼液中添加由氧化钙（CaO）和聚合氯化铝（PAC）组成的混合絮凝剂对沼液进行预处理，降低沼液浊度、化学需氧量（COD）和总磷（TP）质量浓度，以及强化沼液的氨氮脱除潜力，并研究了混合絮凝剂中CaO和PAC的添加顺序、质量浓度配比和总质量浓度的影响。结果表明，CaO/PAC混合絮凝剂中CaO和PAC的添加顺序对沼液净化性能的影响并不显著。降低CaO/PAC中CaO与PAC的质量浓度配比（m_CaO/m_PAC）和增加CaO/PAC总质量浓度均将会降低沼液浊度、COD含量与TP质量浓度，但以沼液pH来表征的沼液氨氮脱除潜能却随着m_CaO/m_PAC值与CaO/PAC总质量浓度的上升而增加。综合考虑混合絮凝剂对沼液的净化性能，CaO/PAC混合絮凝剂总质量浓度可选择12.5～18.75g/L，m_CaO/m_PAC值可选择（2～10）∶1。

关键词: 废水, 沼液, 氨氮脱除, 絮凝剂, 混凝, 环境

CLC Number:

S216.4

TU Te, RAN Yi, HE Qingyao, LIANG Feihong, WANG Ming, YAN Shuiping. Purification performance of biogas slurry by blended CaO/PAC flocculant[J]. Chemical Industry and Engineering Progress, 2018, 37(06): 2392-2398.

涂特, 冉毅, 贺清尧, 梁飞虹, 王明, 晏水平. CaO/PAC混合絮凝剂的沼液净化性能[J]. 化工进展, 2018, 37(06): 2392-2398.

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