Bán Zs, Dave G
Department of Applied Environmental Science, Göteborg University, Box 464, S-40530 Göteborg, Sweden.
Environ Technol. 2004 Jan;25(1):111-21. doi: 10.1080/09593330409355443b.
Struvite [Mg (K, NH4)(PO4) x 6H2O] crystallisation and adsorption to zeolite have been proposed as a method for nutrient recovery from human urine collected with urine separating toilets. The aim of the present study was to optimise the use of MgO (to precipitate struvite) and zeolite (to adsorb ammonia) in this process. The experiments were performed with fresh urine, to which various amounts of MgO and zeolite were added. After repeated stirring and settling for 3 days the supernatant was analysed for pH, total-N, total-P and acute toxicity for Daphnia magna (24- and 48-h EC50). The results show that addition of MgO reduced P and addition of zeolite reduced N in the supernatant, as expected. The required concentration of MgO added was less than expected from the stoichiometric Mg-P-ratio for struvite. In combination with zeolite the requirement for MgO was reduced even further. Zeolite was effective in reducing total-N, but because of its interaction with MgO the effect of zeolite on N as well as P reduction was rather complicated. The optimal combination of MgO and zeolite for combined N and P recovery was found to be around 0.5 MgO per litre urine and 15 g zeolite per litre urine. These additions reduced supernatant P from about 1300 mg l(-1) to 10 mg l(-1) and N from 8000 mg l(-1) to 1000 mg l(-1). The 24-h EC50 for D. magna was not significantly affected by these additions. The expected recovery potentials for P and N by addition of MgO and zeolite are, thus, about 99% for P and 90% for N. However, these figures need to be verified, and pilot plant experiments at a science centre with urine separation wastewater treatment (www.universeum.se) are in progress.
鸟粪石[Mg (K, NH4)(PO4) x 6H2O]结晶以及其在沸石上的吸附作用，已被提议作为一种从使用尿液分离马桶收集的人类尿液中回收营养物质的方法。本研究的目的是优化在此过程中氧化镁（用于沉淀鸟粪石）和沸石（用于吸附氨）的使用。实验使用新鲜尿液进行，向其中添加了不同量的氧化镁和沸石。经过反复搅拌和沉降3天后，分析上清液的pH值、总氮、总磷以及对大型溞的急性毒性（24小时和48小时半数有效浓度）。结果表明，如预期的那样，添加氧化镁降低了上清液中的磷，添加沸石降低了氮。添加的氧化镁所需浓度低于根据鸟粪石化学计量的镁 - 磷比预期的浓度。与沸石结合使用时，氧化镁的需求量进一步降低。沸石在降低总氮方面有效，但由于其与氧化镁的相互作用，沸石对氮和磷还原的影响相当复杂。发现用于联合回收氮和磷的氧化镁和沸石的最佳组合约为每升尿液0.5克氧化镁和每升尿液15克沸石。这些添加量将上清液中的磷从约1300毫克/升降低到10毫克/升，氮从8000毫克/升降低到1000毫克/升。这些添加物对大型溞的24小时半数有效浓度没有显著影响。因此，通过添加氧化镁和沸石预期的磷和氮回收潜力分别约为99%的磷和90%的氮。然而，这些数据需要验证，并且在一个科学中心进行的尿液分离废水处理中试实验（www.universeum.se）正在进行中。
