工艺组合对焦化废水中核心污染物的去除及其能耗分配

Process combination on core pollutants removal from coking wastewater and its energy consumption distribution

以焦化废水为研究对象,结合文献统计与水质特征的分析,研究了厌氧置前与好氧置前2种不同组合工艺对核心污染物的去除与能耗分配的差异性,讨论了焦化废水生物处理工艺的开发可行性。结果表明,前置厌氧与好氧单元对污染物不同的去除机理是构成曝气能耗与碳源需求差别的主要原因。为满足60 m^(3)·h^(-1)设定水质的脱氮目标(TN<40 mg·L^(-1)),O/A/O工艺耗氧量为83.9 kg·h^(-1),A/A/O工艺耗氧量为100.4 kg·h^(-1)。当对废水中的耗氧有机物以及共价结合含氮有机物的预处理较为彻底时,前置好氧工艺在更低能耗下可以实现总氮脱除:A/A/O和O/A/O工艺分别需要122.1 g·m^(-3)和486.9 g·m^(-3)的外部碳源(以甲醇计)来实现总氮的等量去除。A/A/O、O/A/O与O/H/O工艺(H为水解脱氮单元)分别为单污泥、双污泥和三污泥系统运行,在污泥回流和硝化液回流方面的耗能具有显著差异。由于O/H/O工艺不需要污泥回流并且颗粒污泥传氧效率高,故实现脱氮目标的耗氧量仅为53.26 kg·h^(-1),需要的外加碳源可降低至0~220 g·m^(-3),表现出节能与降耗的优势。复杂废水生物处理工艺中存在着反应器结构与单元组合的优化空间,在去除核心污染物以及追求总氮浓度趋零的过程中,需要保证废水中的电子供受体、微生物功能与工艺运行参数在合理区间内。

Taking coking wastewater as the research object,based on literature statistics and analysis of water quality characteristics,the difference of core pollutant removal and energy consumption distribution between two different combined processes of anaerobic pretreatment and aerobic pretreatment was studied,the potentia performance development of biological treatment process of coking wastewater was also discussed.The resul showed that the main reason for the difference between the energy consumption of aeration and the demand of carbon source was the different removal mechanism of pollutants between the pre-anaerobic or pre-aerobic units.In order to meet the nitrogen removal target of 60 m^(3)·h^(-1) set water quality(TN<40 mg·L^(-1)),the oxygen consumption of O/A/O and A/A/O processes were 83.9 kg·h^(-1) and 100.4 kg·h^(-1),respectively.When the thorough pretreatment of oxygen-consuming organic matter and covalent-bonded nitrogen-containing organic matter in wastewater was made,the pre-aerobic process could achieve the removal of total nitrogen with lower energy consumption:A/A/O and O/A/O processes required 122.1 g·m^(-3) and 486.9 g·m^(-3) external carbon sources(measured in methanol)to achieve the equal removal of total nitrogen,respectively.The A/A/O,O/A/O and O/H/O processes(H denotes the hydrolytic denitrification unit)were run as single sludge,double sludge and triple sludge systems,respectively,and showed significant differences in energy consumption in terms of sludge reflux and nitrate reflux.Because the O/H/O process did not require sludge reflux and the granular sludge was highly efficient in oxygen transfer,the oxygen consumption for the achievement of the nitrogen removal targe was only 53.26 kg·h^(-1) and the additional carbon source could be reduced to 0~220 g·m^(-3),demonstrating the potential and superiority of energy saving and consumption reduction.There was scope for the optimization of reactor structures and unit combinations in complex wastewater biological treatment processes.In the process of removing core pollutants and pursuing zero total nitrogen concentrations,it was necessary to ensure the reasonable limits for the electron donor-acceptor,microbial functions and process operating parameters in the wastewater.