Farmers near towns and cities are using a wide range of highly polluted wastewaters for crop irrigation in Pakistan due to severe freshwater shortage. The present study aimed to promote indigenous bacterial strains isolated from domestic, hospital, textile, pharmaceutical and mixed wastewaters to remove contaminants and colour and render these wastewaters safer for irrigation. Thirty seven bacterial strains were isolated from five wastewater samples collected from different sites in Lahore, Pakistan. Under optimal growth conditions, three isolates (D6, D7 and P1) showed >93% decolourisation potential in the treatment of hospital wastewater. 16S rDNA sequencing identified two of these isolates (D6 and D7) as showing 100% and 99.86% homology to Bacillus paramycoides spp. - novel strains from B. cereus group. Isolate P1 showed 97.47% homology to Alcaligenes faecalis. GCMS analysis of the untreated hospital wastewater revealed the presence of pharmaceutic pollutants, i.e. Phenol (876 µg/L), Salicylic acid (48 µg/L), Caffeine (7 µg/L), Naproxen (23 µg/L), Octadecene (185 µg/L) and Diazepam (14 µg/L). The analysis of treated hospital wastewaters showed percentage degradation of pharmaceutic pollutants (100%-43%) and significant reduction in the BOD5 (91%-68%), COD (89%-52%) and heavy metals concentrations. These strains therefore can represent a low-cost and low-tech alternative to bioremediate complex matrices of hospital wastewater prior to crop irrigation to support the achievement of clean re-usable water in developing countries like Pakistan.
Keywords: Alcaligenes faecalis; Bacillus paramycoides spp; biotreatment; irrigation; wastewaters.