Enhancement of Trickling Filter by Porous Concrete in Wastewater Treatment

Abstract

This research studied on the prototype of trickling filter by porous concrete in wastewater treatment. A study was divided into three parts. 1) The synthesis of porous concrete: It was found that porous concrete provided quite rough surface, dark gray in color with cylindrical shape. Porous concrete made from course aggregate sizing of 9.5 mm, the average diameter of 19.83±0.38 cm, average height of 5.16±0.24 cm, average cross sectional area of 308.89±12.19 cm² and average weight of 2.75±0.07 g, were obtained. The average coefficient of water permeability of 0.82±0.04 cm/s and average void ratio of 32.38±1.95 % could be measured. While porous concrete sizing of 19.0 mm, the average diameter of 19.91±0.35 cm, average height of 5.33±0.24 cm, average cross sectional area of 311.48±11.24 cm² and average weight of 2.95±0.09 g, were also obtained. The average coefficient of water permeability of 0.91±0.04 cm/s and average void ratio of 33.78±3.05% could be measured. 2) Sampling of wastewater at grease trap manhole of central canteen, Ubon Ratchathani University was collected and found a pH value of 6.24±0, BOD of 420±0.98 mg/l, COD of 800±0.98 mg/l, SS of 84±0.98 mg/l, and TKN of 33±0.98 mg/l, respectively.  3) The efficiency testing of wastewater treatment by porous concrete in the trickling filter, it was found that the trickling filter tank of porous concrete made from course aggregate sizing of 9.5 mm provided the hydraulic loading rate of 0.38 m³/m²•d which could be categorized as low rate trickling filter type and also organic loading rate of 0.25 kg BOD/m³•d which could be categorized as low rate trickling filter type as well. The pH value in range 5.30-7.70 could be obtained. The efficiency of BOD, COD, SS and TKN treatment have found a better efficiency as compared with porous concrete made from course aggregate sizing of 19.0 mm. The trickling filter tank with porous concrete made from course aggregate sizing of 9.5 mm showed an efficiency in BOD treatment of 96.85±0.37%, while COD, SS and TKN provided an efficiency of 91.60±0.98%, 74.40±0.84% and 81.25±2.94, respectively. The obtained results of pH, BOD, COD, SS and TKN values have passed the wastewater quality standard.

In conclusion, porous concrete made from course aggregate sizing of 9.5 mm. with flow rate of     2 litres/hr, the hydraulic loading rate of 0.38 m³/m²•d and organic loading rate of 0.25 kg BOD/m³•d showed the highest effectiveness in BOD treatment and the result of BOD has found passing in wastewater quality standard. On the contrary, porous concrete made from course aggregate sizing of 19 mm, even the experimental results in series 2-6 provided the high percentage in BOD treatment but the results of the BOD measurement have found not passing the wastewater quality standard. The cause of this unexpectative results may owing to excess grease content in grease trap manhole that reduced the efficiency of trickling filter treatment by porous concrete.