基于乙酸根离子的有机化肥作为正渗透膜反应器的汲取液缓解反应器中的盐积累

Ionic organic acetate-based fertilizers as draw solutions to relieve salt accumulation in forward osmosis membrane bioreactor

为解决正渗透膜反应器中盐积累的问题,选取乙酸铵(NH4C2H3O2)、乙酸钠(NaC2H3O2)和乙酸钾(KC2H3O2)3种基于乙酸根离子的有机化肥作为正渗透膜反应器的汲取液,并将其与硫酸铵((NH4)2SO4)、氯化钠(NaCl)和氯化钾(KCl)3种其对应无机离子汲取液的正渗透(FO)工艺性能和正渗透膜生物反应器(OMBR)工艺性能进行比较。通过工艺水通量和盐含量的测定,生物反应器内COD、铵态氮和硝态氮含量的测定,污染后膜表面的SEM分析,评价了基于乙酸根离子的有机化肥作为正渗透膜反应器的汲取液对反应器内盐积累和膜污染的影响。结果表明:在FO工艺中,乙酸铵、乙酸钠和乙酸钾在0.6 mol·L^-1浓度下的平均水通量分别为10.30、11.07和12.73 L·(m^2·h)^-1,低于其对应的无机离子汲取液的水通量;在OMBR工艺中,乙酸铵、乙酸钠和乙酸钾有机化肥作为汲取液可以显著减缓反应器内盐度的积累。此外,当基于乙酸根离子的有机化肥作为正渗透膜反应器的汲取液时,生物反应器中微生物的生物活性更高,虽然这更容易造成膜污染,但可以有效地去除有机物和氮磷营养物质。研究可为正渗透生物反应器的实际应用提供参考。

To solve the problem of salt accumulation in the forward osmosis membrane bioreactor,the performances of forward osmosis(FO)and osmosis membrane bio-reactor(OMBR)with three ionic organic draw solutes,ammonium acetate(NH4C2H3O2),sodium acetate(NaC2H3O2)and potassium acetate(KC2H3O2)were investigated in this study,which were also compared with those of FO and OMBR with three inorganic draw solutes:ammonium sulfate((NH4)2 SO4),sodium chloride(NaCl)and potassium chloride(KCl).Water flux and salt concentration were measured for comparing the performance of the different draw solutes,COD,ammonium and nitrate concentration were measured to evaluate the biodegradability in the bioreactor.The fouled membrane surface was analyzed by SEM.Results show that the average water fluxes of FO were 10.30,11.07 and 12.73 L·(m^2·h)^-1 at 0.6 mol·L^-1 concentration ammonium acetate,sodium acetate and potassium acetate,respectively,which were lower than those with the inorganic draw solutes.In OMBR process,the ionic organic draw solution could significantly reduce salt accumulation.In addition,when organic fertilizer based on acetate-based ions was used as the draw solution,the biological activity of microorganisms was higher than inorganic fertilizer draw solution,the former could lead to effective removal of organics and nutrients by OMBR though it was easier to form membrane fouling.This study can provide a reference for OMBR practical application.