Study On MABR System Treatment Of Oilfield Produced Wastewater From Offshore Oil Platforms

Oilfield produced wastewater from offshore Oil platforms （OPWFOOP） is verycomplicated, which contains high levels of Oil, salinity, residual surfactant, SS,sulfide, and reductive substances, etc. OPWFOOP is a kind of refractory wastewater,which characteristics of high concentrations chemical oxygen demand （COD）, poorbiodegradability and strong toxicity. Design the combined method of Flotation/Flocculation and Membrane-aerated biofilm reactor （MABR） for the treatment ofOPWFOOP and a good treatment effect was obtained in this study.Flotation/Flocculation is a pre-treatment process for OPWFOOP, the effects ofaeration flow, aeration time, the mass ratio of polymerization aluminumchloride（PAC）/Polyacrylamide（PAM） on the pre-treatment effect was studied, and theresults showed a good pre-treatment effect was got with the condition of aeration flowof10L/min, aeration time of2h, PAC/PAM=750mg/L:187.5mg/L=4:1. The COD、Oiland SS in OPWFOOP were reduced to below300、25and20mg/L, respectively, but theconcentration of NH₄⁺-N was substantially no change.In MABR process section, a type of cylindrical reator of laboratory scale hadbeen designed and manufactured; ADB350M was used to form biofilm in MABR, thecultivation of ADB350M, biofilm growth on the outer-surface of hollow fibermembrane and biofilm acclimation were explored; the initial operation of MABR wasmonitored, and the results showed that MABR was feasible for OPWFOOP, which theremoval rates of COD、NH₄⁺-N and Oil were42%、85%and82%, respectively.In this study, the effects of operating conditions on the MABR performance weresystematically investigated, the optimum operating conditions were: intra-membraneair pressure at0.08Mpa, feed circulation flow rate of0.02m/s, feed pH maintainedOPWFOOP original value, HRT of24h, run at room temperature. The effects ofdifferent harsh conditions on MABR performance were investigated, and the resultsshowed low temperature, aeration ceased, feed fluid circulation ceased and otherharsh conditions were adversely for the normal operation of MABR, and the MABRwell adapted to high-load environment. The particle size analysis showed the particlesize distribution of MABR effluent was estranged bimodal distribution. The long termexperimental results showed: the water quality of MABR effluent was stability, and MABR had a good removal of COD、NH₄⁺-N and Oil, during45⁵5%、90⁹5%and80⁹0%，respectively.MABR is a innovative technology, and it has good application prospects in thetreatment of OPWOOP.