Abstract:
This research studies the efficiency of an anaerobic hybrid filter with a polyethylene plastic media for treating high strength wastewater. The experiments were carried out by using 2 sets of anaerobic filters which were made of 0.07 m. diameter PVC cylinder. Both filters had the same height -2.8 meters. These anaerobic filters contained polyethylene plastic media which had a diameter of 70 mm. And a height of 22 mm. The percent of void ratio was 90% and the surface area was 109 m2/m3 of media which floated up halfway in the tank. The height of the media in the anaerobic filter was 1.25 m. The feeding of wastewater was up flow. The COD of the synthetic wastewater was 5,500 mg/l. The independent variable changes in form of the feeding of wastewater were 7.5, 10, 15 and 30 l/d which corresponds to the organic loading at 3.67, 4.89, 7.33 and 14.67 kg.COD/m3-day, respectively. According to the studies, the COD removal efficiencies are 96, 72, 64 and 44% respectively. The pH of the effluent are 7.05, 6.88, 6.80 and 6.41, respectively. The ORP are -315, -303, -319 and -308 mV, respectively. The temperature of the effluent are 30.9, 27.3, 30.1 and 27.5 ํC. The suspended solids of the effluents are 782, 796, 1080 and 1198 mg/l. The alkalinity of the effluents are 1432, 1360, 1229 and 1477 mg/l. as calcium carbonate, the volatile fattyy acid of the effluents are 428, 583, 615 and 935 mg/l as acetic acid, the quantities of the biogas at the outlet are 9.2, 24.7, 29 and 38.9 l/day. The percentages of methane gas are 57.6, 52.9, 50.2 and 50.3. The methane yield are 0.12 0.24 0.24 and 0.27 l./g.COD removed respectively. The results indicated that the anaerobic hybrid filter can be operated with high efficiency in low organic loading. The higher the organic loading, the lower the efficiency of the anaerobic filter. Furthermore, it is believed that the polyethylene plastic media serves as the screen of the microorganic sludge wash out from the system. The high efficiency of COD removal was observed when the organic loading was lower than 14.67 kg.COD/m3-day