A new treatment process for photo-processing waste using a sulfur-oxidizing bacteria/granular activated carbon system followed by fenton oxidation

Abstract

Establishing a treatment process for practical, economic disposal of photo-processing waste (PW) has become an urgent environmental concern under recently enacted provisions of the London Treaty. This paper describes a new, effective biological/chemical treatment process in which sulfur-oxidizing bacteria (SOB) is used in conjunction with granular activated carbon (GAC), i.e., an aerobic SOB/GAC system, to treat PW prior to Fenton oxidation. Weak dilution PW was treated in a long-term (98 d) continuous treatment such that mass-reduced sulfur compounds were completely oxidized to sulfate, while biodegradable organics in dissolved organic carbon (DOC) were simultaneously degraded at a removal rate of 55%. The remaining refractory/toxic compounds following aerobic SOB/GAC treatment were then effectively transformed to biodegradable organics without pH regulation by adding only 123-154 ml of 30% H2O2, whereas without aerobic SOB/GAC treatment, 670 ml (12% H2O2) was required. Under this innovative approach, DOC in PW was effectively degraded at a removal rate of about 95%, with the required amount of H2O2 being reduced by 77% and the occurrence of sudden boiling being completely removed.