EFFECTS OF ACTIVATED CARBON ON TREATMENT OF PHOTO-PROCESSING WASTE BYSULFUR-OXIDIZING BACTERIA

Establishing economic treatment technology for safe disposal of photo- processing waste (PW) has most recently become an urgent environmental concern. This paper describes a new biological treatment process for PW using sulfur-oxidizing bacteria (SOB) in conjunction with activated carbon (AC). Batch-type acclimation and adsorption experiments using SOB/PAC, SOB/PNAC, and SOB reactor type systems demonstrated that AG e ffectively adsorbs the toxic/refractory compounds which inhibit thiosu lfate oxidization of SOB in PW. Thus, to further clarify the effect of AG, we performed a long-term (approximate to 160 d) continuous-treatm ent experiment on 4- to 8-times dilution of PW using a SOB/GAC system which simulated a typical wastewater treatment system based on an aero bic activated sludge process that primarily uses acclimated SOB. The t hiosulfate load and hydraulic retention time (HRT) were fixed during t reatment such that they ranged from 0.8-3.7 kg S2O32-/1/d and 7.7-1.9 d, respectively. As expected, continuous treatment led to breakthrough of the adsorption effect of GAG. Renewing the GAG and continuing trea tment for about 10 d demonstrated good treatment effectiveness. (C) 19 97 IAWQ. Published by Elsevier Science Ltd.