ABSTRACT
This chapter evaluates Dissolved Air Flotation (DAF) as a method for removal of suspended solids from the effluent stream of a randomly packed fixed-film anaerobic reactor. The Celrobic reactor effluent contains some soluble organic contaminants which are refractory to the bacterial degradation and suspended solids which are predominantly anaerobic bacteria washed out from the reactor packing with some inorganic solids. Initially, the DAF unit was tested without chemicals while the Celrobic reactor was operated in the normal steady-state condition producing low total suspended solids (TSS) effluent. The Jar Tests results, indicated that 100 mg/L of polymer produced the best supernatant and the best settling flocs. In addition to over 90% of suspended solids removal, approximately 35% of the total Chemical oxygen demand (COD) can be removed together with the TSS. Because of the additional benefit of COD removal, the chemical treatment could be used as an emergency backup during the organic overload conditions.
