Volatile fatty acids concentration in real wastewater by forward osmosis
Volatile fatty acids concentration in real wastewater by forward osmosis
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DOI：
10.1016/j.memsci.2019.01.006
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发表时间：
2019-04-01
影响因子：
9.5
通讯作者：
Comas, Joaquim
中科院分区：
文献类型：
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作者：
Blandin, Gaetan;Rossello, Barbara;Comas, Joaquim
研究了正渗透（FO）作为挥发性脂肪酸（VFA，特别是乙酸）的浓缩步骤，以优化下游微生物脱盐池（MDC）。首先，证明了用海水或盐水作为汲取溶液以及进料和汲取溶液的类似流量，可实现废水（WW）的水浓缩因子（WCF）高于10（15-30）。还观察到FO膜的VFA截留率与pH高度相关。在pH= 7.5时，使用国内WW可实现80%以上的截留率，因此FO工艺浓缩VFA是现实的。然而，经预处理的真实的家用WW中存在的VFA的浓度被证明在污垢/生物膜形成方面更具挑战性，这有利于VFA的生物降解。由于污垢减轻（WW预过滤与微滤膜和间歇渗透反冲洗）和生物降解策略（通过应用N-2鼓泡和避免空气接触WW），VFA浓度（特别是乙酸）从60-80高达300-400毫克L-1是可能的。在20个批次的操作中，实现了保持高渗透通量、高VFA回收率和VFA浓缩因子，在高WCF和VFA浓度下，FO浓缩过程的稳定操作更加困难。
Forward osmosis (FO) was studied as a concentration step for volatile fatty acids (VFA, especially acetic acid) to optimise downstream microbial desalination cell (MDC). First, it was demonstrated that water concentration factor (WCF) of wastewater (WW) above 10 (15-30) is achievable with seawater or brine as draw solution and similar flow for feed and draw solution. It was also observed that VFA rejection by FO membrane is highly connected to pH. At pH= 7.5 rejection rates above 80% are achievable working with domestic WW and therefore concentration of VFA by FO process is realistic. Nevertheless, concentration of VFA present in pretreated real domestic WW proved to be more challenging with regards to fouling /biofilm formation which favours the biodegradation of VFA. Thanks to fouling mitigation (WW pre-filtration with microfiltration membrane and interbatch osmotic backwashing) and biodegradation strategies implemented (by applying N-2 sparging and avoiding air contact with the WW), VFA concentration (and especially acetic acid) from 60-80 up to 300-400 mg L-1 is possible. Maintaining high permeation flux, high VFA recovery and concentration factor of VFA during 20 batches of operation was achieved, being more difficult the stable operation of the FO concentration process at high WCF and VFA concentration.