将污水源热泵应用到污泥高温厌氧消化流程,搭建了一套可同时实现污水热能资源化、污泥化学能资源化的实验系统.实验系统中,污水源热泵以污水处理厂二级出水为热源回收其中废热,所产出60℃—70℃中温热能供给热需求约为50℃的污泥高温厌氧消化工艺;高温厌氧消化工艺可快速、有效去除污泥中有机污染物,并产出清洁型能源沼气,而沼气可进一步用于污水处理工艺.实验系统设计了配备板式换热器的间接式污水源热泵系统、加热与维温分立的分块化污泥供热系统,提出了与污泥高温厌氧消化反应需热特性相匹配的热泵分段变工况控制策略.结果显示污水源热泵在供热水温50℃—70℃区间内稳定工作,可为高温厌氧消化提供连续、稳定热环境;供热系统负荷分配均匀,可保持高温厌氧反应器内±1℃温差;污泥水力停留时间5.5d时,挥发性悬浮固体降解率为52.2%,产气率平均为12.4m3/m3污泥(96%含水率).同时进一步利用实测数据分析了二级出水水温及水质对系统运行效率及稳定性的影响.
Municipal sewage treatment plants combine sewage and sludge together.Both of which sewage and sludge can be useful resources.A pilot system was bulit by using a moderately-high temperature sewage source heat pump to thermophilic anaerobic sludge digestion at a municipal sewage treatment plant in Southern China,with the aim to simultaneously provide stabilize sludge and reuse water with the recovery of chemical energy in sludge and thermal energy in sewage simultaneously.By using secondary effluent as the heat source,the heat pump canproduce moderately-high grade thermal energy(60℃—70℃)to supply the heating needed(at about 50℃)for the thermophilic anaerobic digestion.The system was designed by using an indirect-type sewage source heat pump and a fast-adjusting sludge heating system.The results show that the sewage source heat pump could stablize the stable anaerobic reaction temperature with the temperature variation within ±1℃,the digestive gases production rate was 12.4m3/m3(sludge moisture content was 96%),and degradation rates of volatile suspended solid reached 52.2% when hydraulic retention time was 5.5 days.Then a long-term monitoring of secondary effluent temperature and water quality,which influenced the stability and efficiency of sewage source heat pump system,was conducted and the impacts were discussed.