Human urine as a forward osmosis draw solution for the application of microalgae dewatering

In: https://www.sciencedirect.com/science/article/pii/S0304389419306673

Abstract

Human urine is a unique solution that has the right composition to constitute both a severe environmental threat and a rich source of nitrogen and phosphorous. In fact, between 4-9% of urine mass consists of ions, such as K+, Cl-, Na+ or NH4+. Because of its high ionic strength, urine osmotic pressure can reach values of up to 2000 kPa. With this in mind, this work aimed to study the effectiveness of real urine as a novel draw solution for forward osmosis. Water flux, reverse nitrogen flux and membrane fouling were investigated using fresh or hydrolysed urine. Water flux as high as 16.7 ± 1.1 L.m-2. h-1 was recorded using real hydrolysed urine. Additionally, no support layer membrane fouling was noticed in over 20 hours of experimentation. Urine was also employed to dewater a Chlorella vulgaris culture. A fourfold increase in algal concentration was achieved while having an average flux of 14.1 L.m-2. h-1. During the algae dewatering, a flux decrease of about 19% was noticed; this was mainly due to a thin layer of algal deposition on the active side of the membrane. Overall, human urine was found to be an effective draw solution for forward osmosis. ; This research was supported by the National Research Foundation of Korean Grant funded by the Korean Government (MSIP) (No. NRF-2015R1A5A7037825) and by the Australian Research Council through Future Fellowship (FT140101208). HY and CL are grateful for the support of the Korea Institute of Energy Technology Evaluation and Planning (KETEP) through the "Human Resources Program in Energy Technology" project (No. 20164030201010) funded by the Ministry of Trade, Industry and Energy, Republic of Korea.