A pilot plant for the treatment of lemon industry wastewater

Abstract

A pilot plant with a 10-m3 airlift reactor, a settler and a 300-m3 pond were developed for the treatment of the lemon processing industry wastewater. The aim of this work is to evaluate reactor and pilot plant performance. We worked in a continuous system with activated sludge, using wastewater microorganisms and testing the most important parameters of the process (HRT, SRT, F/M, VRC, K La). An outflow settler tube added to the reactor design increased sludge concentration in 25% at 200–500 l/h flow rates. At 600–800 l/h flow rates sludge concentration was 10–15% higher. Volumetric removal capacity of the suspended solid in the reactor was more than 6 kg BOD5/m3 day with lesser than 17 h hydraulic retention time. Maximum BOD5 removal was 92% with 200 l/h flow. The reactor had a good mixing performance and a satisfactory volumetric mass transfer coefficient. Efficient reactor design made foam disposal easy. The effluent came out of the pond with DBO = 50 mg/l, i.e. a total BOD removal of 99% with 600 l/h flow. The pond also had a very important function: it completely eliminated reactor produced biomass by using a natural degradation process.