Bio-remediation of sulfuric compounds from the ceramic wastewater using indigenous bacteria and Thiobacillus thioparus

Sulfide compounds of ceramic industries wastewater cause water pollution as well as plants and aquatic destruction.  This study was aimed to evaluate sulfide compounds removal from ceramic industries wastewater by Thiobacillus thioparus and indigenous wastewater bacterial isolates.   Materials & Indigenous bacterial strains were proliferated at pH of  7, the temperature of 25oC, agitation speed of 200 rpm and an aeration rate of 100 mL min-1 in a 2 L bioreactor for 15 consecutive cycles. Sulfide compounds removal function of T. thioparus and indigenous bacterial strains along with the effect of pH and initial sulfide concentrations were investigated.   The results showed a thiosulfate removal rate of 250 mg sulfide L-1 h-1, a thiosulfate conversion percentage of 100% and a thiosulfate oxidation time of 44 min following 8 consecutive cycles. The sulfide removal rate of T. thioparus and ceramic wastewater indigenous bacteria was obtained as 246.5 and 276.5 mg sulfide L-1 h-1, respectively. Sulfide removal rate by proliferated bacteria decreased from 250 at pH of 7 to 230 and 180 mg sulfide L-1 h-1 at pH of 8 and 9, respectively. Bacterial isolates had an acceptable function in sulfide concentration of 3000 mg L-1, as well. Sulfide removal ability of T. thioparus isolates was decreased by 2.5 and 4 folds, when pH changed from 7 to 8 and 9, respectively. This bacterial strain was not able to tolerate high sulfide concentrations.   The results showed that bacteria isolated from ceramic industries wastewater have a higher capability of sulfide compounds removal as compared to T. thioparus isolates.