Analysis of Recycled Water for Reuse

Recycled water at a facility in Yola, Nigeria was studied for its suitability for irrigation. Biological and physicochemical analyses of the recycled water samples from four different points namely; A (inside pool; chlorinated), B (outlet 1; after chlorination), C (outlet 2; before receiving tank) and D (outlet 3; for irrigation) were carried out for four weeks. The physicochemical analysis include temperature, pH, turbidity, NO3-, total dissolved solids (TDS), Cl-, heavy metals and alkalinity were studied. The pH values obtained varied between 6.9 and 8.1 and were within the acceptable values for irrigation water. The water samples obtained in week 4 had higher turbidity and TDS values as against samples obtained in weeks 1, 2, and 3. High NO3- concentration was found in the water sample taken in weeks 1 and 2 compared to weeks 3 and 4 water samples. Meanwhile, Cl- concentrations were low in the water samples obtained in weeks 1 and 2 relative to concentrations in weeks 3 and 4 water samples. Metals detected from AAS were copper with 4 x 10-5 ppm in all the points (A, B, C and D). The concentrations of iron were 2.72 x 10-3, 5.54 x 10-3, 3.62 x 10-3 and 2.98 x 10-3 ppm in samples A, B, C and D, respectively. Fecal coliforms present were pathogenic coliforms and the Biochemical Oxygen Demand (BOD) analysis showed negative values due to presence of chlorine in the water samples. There are benefits of availability of recycled water for irrigation but care must be taken not to infect users with pathogenic coliforms which are hazardous to health.