Vacuum ammonia stripping from liquid digestate:Effects of pH,alkalinity,temperature,negative pressure and process optimization  

作　　者：Qiuhong Chen Donghai Yang Xiang Chen Xiankai Wang Bin Dong Xiaohu Dai 

机构地区：[1]State Key Laboratory of Pollution Control and Resource Reuse,College of Environmental Science and Engineering,Tongji University,Shanghai 200092,China [2]YANGTZE Eco-Environment Engineering Research Center,National Engineering Research Center of Eco-environment Protection for Yangtze River Economic Belt,China Three Gorges Corporation,Wuhan 430010,China

出　　处：《Journal of Environmental Sciences》2025年第3期638-650,共13页环境科学学报(英文版)

基　　金：supported by the National Key Research and Development Program of China(No.2020YFC1908702);the National Natural Science Foundation of China(No.52131002);the Science and Technology Commission of Shanghai Municipality(No.22dz1209200);China Three Gorges Corporation(No.202403018).

摘　　要：High ammonia-nitrogen digestate has become a key bottleneck limiting the anaerobic digestion of organic solid waste.Vacuum ammonia stripping can simultaneously remove and recover ammonia nitrogen,which has attracted a lot of attention in recent years.To investigate the parameter effects on the efficiency and mass transfer,five combination conditions(53℃ 15 kPa,60°C 20 kPa,65°C 25 kPa,72°C 35 kPa,and 81°C 50 kPa)were conducted for ammonia stripping of sludge digestate.The results showed that 80%of ammonia nitrogen was stripped in 45 min for all experimental groups,but the ammonia transfer coefficient varied under different conditions,which increased with the rising of boiling point temperature,and reached the maximum value(39.0 mm/hr)at 81°C 50 kPa.The ammonia nitrogen removal efficiency was more than 80%for 30 min vacuum stripping after adjusting the initial pH to above 9.5,and adjustment of the initial alkalinity also affects the pH value of liquid digestate.It was found that pH and alkalinity are the key factors influencing the ammonia nitrogen dissociation and removal efficiency,while temperature and vacuum mainly affect the ammonia nitrogen mass transfer and removal velocity.In terms of the mechanism of vacuum ammonia stripping,it underwent alkalinity destruction,pH enhancement,ammonia nitrogen dissociation,and free ammonia removal.In this study,two-stage experiments of alkalinity destruction and ammonia removal were also carried out,which showed that the two-stage configuration was beneficial for ammonia removal.It provides a theoretical basis and practical technology for the vacuum ammonia stripping from liquid digestate of organic solid waste.

关 键 词：Liquid digestate Vacuum ammonia stripping ALKALINITY Mass transfer Process optimization 

分 类 号：X701[环境科学与工程—环境工程]