Performance Evaluation of Locally Fabricated Point-of-Use (PoU) Clay Filters with Organic Additives for Turbidity Removal in Rural Household Water Treatment

Abstract

This paper evaluates, tests, and economically evaluates a Point-of-Use (PoU) clay filter, impregnated with natural materials, for turbidity removal from rural drinking water in Maharashtra, India. The work emphasizes use of locally available resources and real household operating conditions to produce an affordable, field-validated treatment option. The Point-of-Use (PoU) clay filter was fabricated from clay blended with combustible organics (sawdust or groundnut shell powder) that burn out during firing to create a porous module, assembled in a PVC-based housing with copper piping and a brass outlet nozzle. Source water was taken from Warna River supply to Haripur village, which, after sand filtration, still failed to meet IS 10500:2012 turbidity limits, and was treated in 20 L batch runs under dayto-day household usage. Flow rate was determined by the time–volume method, while turbidity of influent and filtrate was monitored using a calibrated turbidity meter; modules were periodically backwashed and their hydraulic and removal performance tracked over cumulative throughput. Two module formulations were evaluated: Module 1 (sawdust-based) and Module 2 (groundnut shell-based), enabling assessment of the influence of organic additive on porosity, flow, and longevity. Module 1 achieved an average turbidity removal efficiency of 90.14 ± 0.37%, reducing raw water from 6.02 ± 2.69 NTU (up to 13.40 NTU) to 0.58 ± 0.27 NTU, consistently satisfying IS 10500:2012 turbidity standards, with mean flow rate of 67.77± 52.00 LPH and about 80% flow restoration after backwashing. Module 8 showed lower performance, with 74.58 ± 0.58% removal, residual turbidity of 1.46 ± 0.52 NTU, lower flow (23.21 ± 21.11 LPH), and weaker hydraulic recovery and shorter predicted lifespan. Performance was consistent between laboratory and PoU operation across turbidity ranges, confirming the robustness of the design. A detailed cost analysis gave a unit cost of about INR 620, less than half that of comparable commercial candle filters (~INR 1400), while delivering similar or better turbidity removal. The study demonstrates that sawdust-based Point-of-Use (PoU) clay filter can provide a technically effective, low-cost, and locally manufacturable solution for rural household water treatment in developing regions.