RO brine treatment and recovery by biological activated carbon and capacitive deionization process.

The generation of brine solutions from dense membrane (reverse osmosis, RO or nanofiltration, NF) water reclamation systems has been increasing worldwide, and the lack of cost effective disposal options is becoming a critical water resources management issue. In Singapore, NEWater is the product of a multiple barrier water reclamation process from secondary treated domestic effluent using MF/UF-RO and UV technologies. The RO brine (concentrates) accounts for more than 20% of the total flow treated.

Preliminary study of osmotic membrane bioreactor: effects of draw solution on water flux and air scouring on fouling.

Preliminary study on a novel osmotic membrane bioreactor (OMBR) was explored. Objective of this study was to investigate the effects of draw solution on membrane flux and air scouring at the feed side on fouling tendency in a pilot OMBR system composing the anoxic/aerobic and forward osmosis (FO) processes. Domestic sewage was the raw feed, FO membrane from HTI and NaCl/MgSO4 draw solutions were used in the experiments.

Experimental studies and modeling on concentration polarization in forward osmosis.

Concentration polarization (CP) is an important issue in forward osmosis (FO) processes and it is believed that the coupled effect of dilutive internal CP (DICP) and concentrative external CP (CECP) limits FO flux. The objective of this study was to distinguish individual contribution of different types of DICP and CECP via modeling and to validate it by pilot studies. The influence of DICP/CECP on FO flux has been investigated in this study.

Pilot study of a submerged membrane bioreactor for water reclamation.

The objective of this pilot study was to investigate the operational conditions of newly developed MBR modules for water reclamation under tropical conditions. MUDC-620A MBR modules with hollow fibre PVDF membranes from Asahi-Kasei Chemicals were used in the study. The pilot plant with capacity of 50 m(3)/d was operated continuously (24-hour) over four months on site of Ulu Pandan Water Reclamation Plant (UPWRP) in Singapore.

Integrated pretreatment with capacitive deionization for reverse osmosis reject recovery from water reclamation plant.

Reverse osmosis (RO) reject recovery from the water reclamation process was demonstrated feasible using an integrated pretreatment scheme followed by the Capacitive Deionization (CDI) process. The RO reject had an average total dissolved solids (TDS) of 1276+/-166 mg/L. Water recovery of 85% with water quality comparable with the RO feed was achieved.

Ozone-biological activated carbon as a pretreatment process for reverse osmosis brine treatment and recovery.

Ozonation was used in this study to improve biodegradability of RO brine from water reclamation facilities. An ozone dosage ranging from 3 to 10 mg O(3)/L and contact times of 10 and 20 min in batch studies were found to increase the biodegradability (BOD(5)/TOC ratio) of the RO brine by 1.8-3.

A modeling study of fouling development in membrane bioreactors for wastewater treatment.

Membrane fouling is a primary concern in membrane bioreactors (MBRs) in wastewater treatment because it strongly affects both system stability and economic feasibility. A mathematical model was developed in this study for membrane fouling in submerged MBR systems for wastewater treatment, in which both reversible and irreversible fouling were quantified. While mixed liquor suspended solids are the major components of the reversible fouling layer, dissolved organic matter is thought to be the key foulant, in particular, responsible for the long-term irreversible fouling of the filtration unit.