Bio-treatment of maize processing wastewater using indigenous microorganisms

Abstract

Wastewater arising from maize processing industry is rich in proteins, amino acids, carbohydrates and nitrogenous compounds. Discharging of such wastewaters to the main water bodies without proper treatment creates environmental risks. The present research aimed to reduce maize processing wastewater contaminants by indigenous microorganisms. Industrial wastewater samples of maize processing factory at 10th of Ramadan city, Egypt were collected. The chemical and microbiological characteristics of samples were evaluated. An in vitro batch experiment was conducted in triplicates using 5 L Erlenmeyer flasks enriched with 2 L of the maize processing wastewater and incubated under shaking ambient conditions at 120 rpm for 30 d. Another 2 L Erlenmeyer flask was enriched with 2 L of the wastewater sample, and incubated under static ambient conditions, used as control. The biodegradation of nitrogenous and organic compounds was followed up by measuring Total Kjeldahl Nitrogen (TKN), Biochemical Oxygen Demand (BOD), Chemical Oxygen Demand (COD), Dissolved Oxygen (DO) and pH. The biomass growth rate was monitored by counting the viable bacterial cells (TBC) and fungal cells. The concentration of TKN, BOD and COD was reduced from 2330, 9000 and 12,000 mg L-1 to 420, 220 and 430 mg L-1, respectively. DO concentrations were ranged between 6 to 12 mg L-1 and the pH value was elevated from 6.9 to 9.3. TBC was elevated from 2 × 106 to 4 × 1010 CFU mL-1, while the yeast count was reduced from 12 × 106 to 2.2 × 104 CFU mL-1. Microbial identification by Analytical Profile Index (API) profiling kits indicated that Saccharomyces cerevisiae, Bacillus subtilis, Bacillus amyloliquefaciens, and Bacillus licheniformis are the strains involved in bio-treatment.