Sustainable Membrane Performance for Refinery Reuse of Non-nitrified Wastewater

Central San owns and operates a wastewater treatment plant with a low solids retention time (SRT) activated sludge secondary treatment process. Low SRT secondary effluent can be challenging to filter and MF/UF vendors typically specify operation on a higher SRT fully nitrified secondary effluent. The goals of the pilot were to establish sustainable operating conditions for both MF/UF and RO as well as demonstrate that the product water would be fit for purpose for non-potable industrial reuse (low TDS, ammonia, and metals) at two nearby refineries. The pilot provided critical information to confirm that non-potable refinery reuse is achievable without upstream secondary treatment upgrades. Sustainable MF/UF fluxes up to 40 gfd with 2.5 mg/L ferric chloride as Fe and up to 30 gfd with 10 mg/L aluminum chlorohydrate coagulants were observed. The RO operated sustainably for almost three months and did not require a CIP.