A hybrid biological reactor (HBR) which contained both suspended- and attached-growth biomass was developed by introducing sponge materials into a regular activated sludge unit and used for the treatment of seafood processing wastewater. | Journal of Fisheries science and Technology Special issue - 2015 WASTEWATER TREATMENT IN THE HYBRID BIOLOGICAL REACTOR: EFFEECTS OF HYDRAULIC RETENTION TIME AND OXYGEN SUPPLY ON TOTAL NITROGEN REMOVAL AND NITRIFICATION Nguyen Thị Ngoc Thanh1, Pham Khac Lieu2 ABSTRACT A hybrid biological reactor (HBR) which contained both suspended- and attached-growth biomass was developed by introducing sponge materials into a regular activated sludge unit and used for the treatment of seafood processing wastewater. The HBR was operated over 170 days, to assess the effect of hydraulic retention time (HRT) and oxygen supply conditions on total nitrogen (TN) removal efficiency. The HBR was supplied with oxygen at three different levels: 1, and 2 L/min, and HRT was maintained for 8 h. Results indicate oxygen levels of 1 and L/min, had higher efficiencies (60% of total nitrogen was removed) than an oxygen level of 2 L/min (48%). The HRT was changed at 8, 10 and 12 h and the rate of oxygen supply was maintained at L/min. Each run was operated for at least 15 days. In general, the percentage of TN removed increased linearly with increasing HRT. More than 65% TN could be removed up to a HRT of about 10 - 12 h, which indicates that this hybrid system was highly effective. In this experiment, the nitrification rates were very high, more than 90%, and the best result of nitrification was () at HRT = 12 h, and an oxygen supply of L/min. Keywords: Hybrid biological reactor, Wastewater treatment, Activated sludge process, Nitrification I. INTRODUCTION Wastewater treatment via aerobic processes has some problems that remain unsolved for the conventional activated-sludge process, such as a large space requirement, complicated system operation and large excess sludge production [6-7]. The expense for excess sludge treatment has been estimated to be half of the total cost of wastewater treatment plant operations [11]. A hybrid reactor consists of both suspended and attached
