Feasibility of membrane distillation process for potable water reuse: A barrier for dissolved organic matters and pharmaceuticals

Abstract

In this study, the feasibility of the membrane distillation (MD) process as a wastewater reclamation system for portable reuse was investigated. The flux was stably maintained at about 20 L/m²h (LMH) at ΔT 30 °C, compared to higher flux at ΔT 50 °C, which showed a rapid decrease in the flux due to severe fouling. MD produced excellent quality of potable water satisfied the drinking water standards of Korea from effluent of sewage treatment plant (ESTP). The fractions of the hydrophobic OC (HOC) and chromatographic DOC (CDOC) from LC-OCD analysis was firstly suggested to understand different organic transport during the MD process. The transport of organic matters across the MD membrane mitigated at low operation temperature and the transported organics in all the tested waters were mostly volatile low molecular weight organics, aromatic amino acids. All of thirteen selected pharmaceuticals were completely removed by MD, regardless of their properties. In order to retard the membrane fouling of the MD process, coagulation and filtration pre-treatments were applied. The pre-treatment process coupled MD process could successfully remove impurities including NH₄-N without severe membrane fouling. Moreover, coagulation pretreatment reduced transport of ammonia due to decrease in pH.

Keywords: Membrane distillation; Organic transport; Pharmaceuticals; Potable water reuse; Pre-treatment.