污水管自然脉冲通气对生物膜群落结构演变及MA、SRB活性抑制机制研究

Urban security and groundwater quality are threatened by explosions and corrosion of sewer pipe, which are resulted from the emission and enrichment of methane and hydrogen sulfide in the sewer system. Ventilation from blowers into the sewer systems has ability to reduce the risk of these harmful gases by inhibiting their producing bacterium and increasing gases diffusion. A new idea for mitigating harmful gases risk is proposed in the project, which utilize the pulsed airflow during intermittent draining from the drainage risers inside buildings，in order to enhance the nature ventilation of the sewer system. The pulsed air motion and distribution into the sewer pipe from the drainage risers, the gas-liquid interfacial mass transfer under the pulsed airflow，the microbial community structural of the wastewater and biofilm on the sewer pipe wall under the pulsed airflow are the most important theory parts for applying the idea. In order to reveal these laws about air distribution and air partial pressure of the pulsed airflow, A special experimental installation was designed，the real-time air pressure and air velocity of the pulsed airflow in the installation are detected by some sensors , the airflow filed is measured by 3D-PIV， finally the airflow filed in actual sewer pipe is simulated by CFD based on adjusted parameters by these measured resulted in the experimental installation. The change rules of dissolved oxygen and hydrogen sulfide near interface in the gas-liquid interfacial mass transfer process are discovered with the aid of the Laser holographic interferometry and Doppler velocity measurement. By using of Microelectrode, Gradient PCR and so on, it is easy to discover the microbial community structural of biofilm and the activity of bacteria colony in wastewater, its aims are the growth and metabolism the Methanogens bacteria and Sulfate reducing bacteria under the pulsed airflow. This project will establish a nature ventilation theory and a new nature ventilation technology for the sewer system , which provides theoretical and technical support for planning sewage pipe network and mitigating harmful gases risk in sewer system.

污水管网的爆炸和腐蚀严重威胁着城市安全和地下水环境，主要原因是管道中产生的甲烷和硫化氢。鼓风通气能抑制产甲烷菌（MA）和硫酸盐还原菌（SRB）活性，增强有害气体扩散。本项目提出了利用建筑立管间歇排水形成的脉冲气流自然控制有害气体的新思路，涉及了立管间歇排水通入污水管道中的脉冲气流组织、脉冲气流环境中气液界面传质和其影响下污水管道中生物群落结构特性等内容。通过压力及风速在线检测，气体流场的PIV测定及CFD模拟，揭示间歇排水引起的气流组织和气体分压的脉冲规律；通过激光全息干涉和多普勒流速测量，探明脉冲气流环境中气液传质过程近界面溶氧和硫化氢的变化规律；借助微电极和荧光定量PCR仪等，发现脉冲气流环境中生物群落结构特征及菌落活性，掌握MA和SRB在溶氧变化环境中的生长代谢规律。项目建立的污水收集系统自然通气理论与构造，能有力支撑污水管道有害气体控制新技术和污水收集系统的规划设计新方法的建立。

针对污水管道危害气体产生与散逸引发的城镇臭味、管道腐蚀、维护人员中毒及管道爆炸等问题，本项目提出了利用建筑立管排水势能驱动形成的自然脉冲气流控制危害气体产生的新方法。项目结合污水管网现场调研、实验室模拟实验、计算机仿真模拟等研究方法开展了系统研究。解析了污水管网有害气体时空分布特性与污水管道工况运行条件、水质参数、环境因子的关联关系，明确了污水管网危害气体产生的主控因子及生化作用机制；模拟了建立排水过程及系统内外温差驱动下建筑立管气体流动特性及压力变化，建立了基于建筑排水及温差驱动的立管气流数值模型，并进行了模型校准与验证，在此基础上阐明了建筑立管中脉冲气流组织规律；结合污水管道气液界面氧传质及污水氧消耗过程分析，明确了脉冲通气条件下气液界面氧传质过程及污水溶氧响应特性；通过设置气体帘幕及风机等实现了建筑立管-污水管道-建筑立管有组织通风，形成了基于控制气体流速从而增强气液界面氧传质的技术方法；脉冲通气对污水管道典型危害气体H2S和CH4产生的总体抑制率为49%和39%，体现了良好的技术效能；分析了脉冲通气对污水管道污染物转化的影响，明确了脉冲通气条件下生物膜和管道沉积物微生物群落结构演替、污水管道溶氧及氧化还原电位等环境因子响应特性；结合脉冲气流组织规律、气液界面氧传质及溶氧响应、微生物群落结构演替、危害气体产生抑制效能分析结果，系统地揭示了基于建筑立管脉冲通气抑制危害气体产生的作用机理。项目研究成果为污水管道有害气体控制新技术和污水收集系统的规划设计新方法建立提供理论与技术支撑。