Treatment of Palm Oil Mill Effluent (POME) Supernatants Using Aerobic Attached–Growth System: Trickling Filter as a Case Study

Abstract

Kertas kerja ini membincangkan tentang kecekapan penuras cucur dalam merawat supernatan kumbahan kilang kelapa sawit (POME). Supernatan POME diperoleh menerusi dua jenis perawatan. Dalam perawatan 1, pengendapan graviti digunakan untuk menyingkir pepejal boleh mendak. Perawatan 2 digunakan untuk menyingkir pepejal boleh mendak dan gumpalan partikal dengan menggunakan 350 ppm alum. Influen dialurkan secara titisan pada biojisim yang terlekat pada penyokong pepejal rawak PVC setinggi 1 m. Penuras cucur berupaya menyingkir lebih daripada 90.0% dari keperluan oksigen biologi (BOD) dan keperluan oksigen kimia (COD) di bawah 1 m3/m2–hari. Pada 2.53 m3/m2–hari, influen dengan Perawatan 1 menghasilkan kecekapan penyingkiran COD sebanyak 40.3%, berbanding 83.1% bila Perawatan 2 digunakan. Perkara ini berlaku berikutan penyingkiran bahan organik tak boleh resap semasa Perawatan 2. Kecekapan penyingkiran menurun dengan meningkatnya bebanan hidraulik kerana wujudnya kelemahan dalam hidrolisis bahan tak boleh resap kepada substratum larut. Dengan edaran semula (α=1), penyingkiran BOD dan COD yang lebih tinggi dicapai di bawah 7 m3/m2–hari. Pencapaian ini disebabkan oleh bebanan organik yang lebih rendah serta pergedaran semula enzim dan biojisim yang aktif kepada sistem. Perawatan 2 menghasilkan enap cemar yang lebih tinggi kerana penukaran substratum boleh larut kepada biojisim tak boleh larut. Hidrolisis bahan organik tak boleh resap didapati berlaku secara aktif pada bahagian atas penuras cucur sementara bahagian bawahnya cenderung mengoksidakan substratum organik. Kata kunci: POME, turas cucur, bahan organik bolehresap, penggumpalan, alir semula This paper discusses the efficiency of a trickling filter to treat Palm Oil Mill Effluent (POME) supernatants. POME supernatants were obtained via two treatments. In Treatment 1, gravity sedimentation was used to remove settleable solids. In Treatment 2, both settleable solids and colloidal particles were removed using 350 ppm of alum. The influents were allowed to trickle over biomass attached to 1 m high random PVC solid support. Below 1 m3/m2–day, the filter demonstrated Biological Oxygen Demand (BOD) and Chemical Oxygen Demand (COD) removal efficiencies of more than 90.0%. At 2.53 m3/m2–day, the influent with Treatment 1 gave a COD removal efficiency of 40.3%, but increased to 83.1% when the influent with Treatment 2 was used. This was ascribed to the removal of non–diffusible organics during Treatment 2. The removal efficiencies decreased with an increase in hydraulic loading due to limitations in the hydrolysis of non–diffusibles into soluble substrates. With recirculation (α=1), higher BOD and COD removals were achieved below 7.0 m3/m2–day, attributed to lower organic loading and the recycling of active enzyme and biomass to the system. The influent with Treatment 2 demonstrated higher sludge production due to higher conversion of soluble substrates into insoluble biomass. Hydrolysis of non–diffusible organics mainly took place at upper reaches of the filter column while lower reaches were involved in oxidizing the organic subtrates. Key words: POME, trickling filter, diffusible organic, coagulation, recirculation