A new method of biological start-up in Arak activated sludge wastewater treatment plant

Starting up a wastewater treatment plant (WWTP) is one of the most important stages of operation. A new method was used to start Arak activated sludge WWTP up, which took in advantages of the other methods. Primarily just one of the basins was in the lane and wastewater entered the plant part by part. At first 1/30, second week 1/15, third week 1/6, and fourth week 1/3 of total inflow came to the plant. Observing little progress of biomass gain, some sludge from a similar treatment plant was added to the system, as seed. This procedure continued so the MLSS of the system, attained the 1/3 total design MLSS which was design MLSS of one basin. In the next two weeks, by using developed sludge of the self-system the second and third basins came in the lane and inflow increased to 2/3 and total flow, respectively. Finally after two months of beginning the start-up and one month after adding the seed total desired biomass was developed and the plant started to waste sludge. Because of cold weather start-up period took a longer time than expected. But even before developing biomass environment friendly results were achieved. After attaining design MLSS, BOD5 and COD removal from 40% and 60% increased to 90% and TSS removal from 70% reached to 96%. Less loading, less foam forming, no bacteriologic and chemical problems, better process control, using less seed, saving costs in sludge transport and avoiding relevant problems were the main advantages of this method.