EVALUATING THE APPLICATION OF CHAMO LAKE MICROORGANISMS IN TEXTILE WASTEWATER TREATMENT UNDER ANOXIC-OXIC CONDITION

Abstract

Textile wastewater is characterized by substantial organic load, extreme alkalinity and heavily colored effluent. When it is discharged without treatment, some of these effluents become toxic to the public and environmental health. To solve these problems, there are physical, chemical and biological treatment methods. Having inherent drawbacks for physical and chemical methods, biological methods which involve microbial activities are the best alternative textile wastewater treatment practiced worldwide. This study was designed to evaluate the activity of alkaliphilic microbial consortia under sequential anoxic-oxic bioreactor configurations. Synthetic wastewater containing mineral salt media and reactive red 239 (RR 239) were enriched with samples collected from Lake Chamo. Considering the microbial metabolic activates, the anoxic and oxic reactors were inoculated with sediment and water samples, respectively. The effects of organic loading rates (OLR), hydraulic retention times (HRT) and dye concentrations were evaluated for biological oxygen demand (BOD5), nitrogen (N) and dye removal potentials. Increasing the OLR from 0.5 to 1.25 kg/day were showed a decreasing in BOD5 removal efficiency was (85.5± 4 to 43.1±4% under oxic and 63.5±3 to 23.1±1.5%) under anoxic condition and dye removal increases from (1.5±0.1 to 5.7±2% under oxic and 80±0.4% to 94.5±0.5 under anoxic conditions). However, increasing the OLR showed an increasing trend of denitrification from (1±0.1 to 3±0.1% and 53±3 to 60±3.5%) under anoxic and oxic conditions, respectively. Increasing the HRT from 5 to 25 hrs were found increasing the BOD5 removal efficiency (41.4±.4 to 66.3±1.5% under anoxic and 84.4±6.8 to 85.5 ±7.3%) under oxic conditions and under longer HRT conditions, color removal efficiencies were also improved under oxic condition (8.8±2.3 to 27 ±3%) and under anoxic condition (57.6±4.5 to 91±5%) condition. Increasing the concentration of RR 239 from 10 to 50 mg/L was found a negative impact on color removal. Overall, anoxic condition showed better dye removal efficiency than BOD5 and denitrification most likely indicating dye under oxygen tension condition served as a final electron accepter.