Laundry wastewater contains surfactants, sodium tripolyphosphate, carboxymethyl cellulose, oil stains, dust particles, and various microorganisms, etc., with turbid appearance, alkaline pH, high suspended matter content, and high ammonia nitrogen and phosphorus content. , Phosphate entering the water body will cause the eutrophication of the water body. After the surfactant enters the water body, it will poison aquatic animals and plants to death, solubilize some micro-pollutants in the water, and must be treated before they can be discharged.
The application of membrane bioreactor (MBR) for industrial laundry wastewater treatment is presented. An MBR pilot plant installation was used to test the efficiency of surfactant removal and the influence of treatment time on permeate flux. The installation consisted of (1) biological reactor (three tanks with a total capacity of 600 dm3 ), (2) membrane reactor (ZeeWeed 10 membrane module, GE Water & Process Technologies), and (3) dosing station. The hourly flow rate of the wastewater to the biological reactor amounted to Qh = 25 dm3 h–1. The effluent from the bioreactor was periodically recycled back to the membrane reactor at Qh = 125 dm3 h–1. Despite periodical relaxation and backflush with permeate, after about 11 d of operation, the membrane was fouled and chemical cleaning was necessary. The membrane permeability was fully recovered after the applied cleaning procedure. The total efficiency of removal of anionic and non-ionic surfactants was in the range of 87%–95% and 94%–95%, respectively. The COD removal reached 91%–93% and the BOD was almost completely eliminated (99%) indicating high MBR treatment efficiency of the applied industrial laundry wastewater.