MODELLING THE INFLUENCE OF ROOF MATERIALS TYPE AND PITCH ON HARVESTED RAINWATER QUANTITY AND QUALITY

Abstract

The study focuses on the rainwater harvesting system which provides loads of benefits to plants, animals and human lives for survival. On the basis, a small-scale rainwater harvesting structure was assembled in the Teaching and Research Farm of the Department of Agricultural Engineering, Adeleke University Ede, Osun-State. It lies between Longitude 4o 431 and 590 991 South Greenwich Meridian and Latitude 70 431 and 590 991 north of the Equator. Experiments were analyzed to evaluate the optimization and modeling on quality and quantity of harvested rainwater on physicochemical and heavy metals properties on four roofing sheet materials, such as Aluminium, Fiber, Asbestos and Biomass based materials and roof pitch (30o, 40o and 45o). The volume of harvested rainwater was measured for various samples. The statistical analysis showed that all the variables affect the volume of harvested rainwater. From the results obtained, the optimal condition was obtained at 30o tilt angle for fiber roof material which gave 4.39 litres of water, 26.48 mg/l BOD, 38.87 ppm Total suspended solids, 40.32 mg/l COD, 3.20 NTU turbidity, 6.05 UpH, 692.13 mg/l Total dissolved solids, 393.87 mg/l calcium level, 28.81 mg/l potassium level, 9.62 Zinc level, 200 mg/l sulphate level, 160.44 mg/l Iron level at an overall desirability of 54% which showed a good agreement. The optimum solutions obtained is based on the constraints of optimization on the roof materials and angle of tilt. There is high correlation coefficient values obtained in heavy metal concentration compare to standard values. All these obtained results were compared with permissible values in accordance with IS 10500; WHO, 1984, 2011; FAO/WHO, 1988 standards.