Performance evaluation of trickling filter-based wastewater treatment system utilizing cotton sticks as filter media

The need of wastewater (WW) treatment is increasing along with the production of WW and its disposal without treatment. With a smaller footprint, ease of operation, and relatively less cost, trickling filter (TF) wastewater treatment systems have been considered to be more adoptable for domestic and industrial WW treatment in underdeveloped and/or developing countries – particularly for Asia and Africa. A relatively low-cost and operationally effective TF wastewater treatment system was developed using farm waste cotton sticks as biofilm support media. During the operation of the TF system, flow rates vary from 1.7 to 4.6 m³/hr. The attained removal efficiency for BOD (biological oxygen demand) was 69-78% and for chemical oxygen demand (COD) was 65-80%. The solids removal in TF system was 38-56% for total suspended solids (TSS) and 20-36% for total dissolved solids (TDS). Other aggregates such as turbidity and color removal were 32-54% and 25-42%, respectively. Four to five months of trouble-free operation of the developed TF system indicated the robustness and reliability of the system. Cotton sticks appeared to be a degradation-resistant alternative filter media for the TF system. Moreover, it is useful for reducing potential impacts of WW re-use at the farm level. Treated effluents through the TF system can be re-used as an irrigation water supplement in under-developed and/or developing countries.