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Efficiency of a locally designed pilot-scale trickling biofilter (TBF) system in natural environment for the treatment of domestic wastewater

Rasool, Tabassum, Rehman, Abdul, Naz, Iffat, Ullah, Rahat, Ahmed, Safia
Environmental technology 2018 v.39 no.10 pp. 1295-1306
biochemical oxygen demand, biofilters, chemical oxygen demand, cost effectiveness, dissolved oxygen, electrical conductivity, fecal bacteria, most probable number technique, municipal wastewater, nitrogen content, phosphates, sewage, sulfates, temperature, total suspended solids, wastewater treatment
In the present study, a cost-effective and simple stone media pilot-scale trickling biofilter (TBF) was designed, constructed and operated in a continuous recirculation mode for wastewater treatment with a hydraulic flow rate of 1.2 L/min (Q = 0.072 m³/h) and hydraulic loading (Q/A) of 0.147 m³/day for 15 weeks at a temperature range of 14.5–36°C. A substantial reduction in the average concentration of different pollution indicators, such as chemical oxygen demand (COD) (85.6%), biochemical oxygen demand (BOD₅) (85.6%), total dissolved solid (TDS) (62.8%), total suspended solid (TSS) (99.9%), electrical conductivity (EC) (15.1%), phosphates (63.22%), sulfates (28.5%) and total nitrogen (TN) (34.4%), was observed during 15 weeks of operational period. Whereas a considerable average increase in the levels of dissolved oxygen (DO) (63.2%) was found after treatment of wastewater by the TBF system. No significant reduction in most probable number (MPN) index of fecal coliforms was observed in the effluent in first 9 weeks of operation. However, a significant reduction in the MPN of fecal coliforms was observed, i.e. 80–90% in the last few weeks of treatment. Thus, overall results suggest that pilot-scale TBF has a great potential to be transferred to field scale for treating sewage for small communities in developing countries, in order to produce effluent of good quality, which can be safely used for irrigation as well as ornamental purposes.