Nitrification Rate in the Bioremediation of Organic Wastewater using Chlorella sp. and Nitrifying-Denitrifying Bacteria | Laju Nitrifikasi pada Bioremediasi Air Limbah Organik Menggunakan Chlorella sp. dan Bakteri Nitrifikasi-Denitrifikasi

anglais. Global nitrogen pollution in the aquatic environment has been increased mostly due to the disposal of organic wastewater from human activities. Chronic disposal of nitrogen compounds into the waters  causes eutrophication and death of aquatic organisms. Process of reducing nitrogen in wastewater can be carried out economically and efficiently using nitrifying-denitrifying bacteria. Beside that, another environmentally friendly technology that can also be used is bioremediation using microalgae such as Chlorella sp. The synergistic relationship between bacteria and microalgae has a potential to better reduce performance of nitrogen compounds in organic wastewater. This study, which was conducted from July to August 2020, was laboratory experiment using randomised block design. It aimed to determine growth rate of Chlorella sp., rate of nitrification, rate of changes of nitrate compounds, effect of differences between treatments and duration of the changes of nitrate levels in organic wastewater as also relationship between Chlorella sp. to the nitrifying-denitrifying bacteria. Fresh wastewater samples were taken from Lake Rawa Pening. The results showed that growth pattern of Chlorella sp. has increased until the peak day (day 6) then decreased toward day 9. The highest nitrification rate was performed by treatment C, i.e., 0.2 mg NH4-N.l-1.hour-1 followed by treatment B, D and A respectively, 0.169, 0.009 and 0.008 mg NH4-N.l-1.hour-1. Similarly, the highest percentage change in nitrate compounds during the study was treatment C (1874%), B (1664%), D (200%) and A (175%) subsequently. The analysis of variance between treatment for changes in nitrate compounds was significantly different (p value <0.05). A further DMRT/Duncan Multiple Range Test showed that the highest average was also treatment C, B, D and A.

indonésien. Pencemaran nitrogen secara global begitu meningkat akibat pembuangan air limbah organik bersumber dari aktivitas manusia yang mencemari lingkungan perairan. Peningkatan senyawa nitrogen secara terus menerus dan dalam waktu yang lama menjadi penyebab terjadinya eutrofikasi dan kematian organisme. Proses reduksi nitrogen pada air limbah dapat dilakukan secara ekonomis dan efisien menggunakan bakteri nitrifikasi-denitrifikasi. Teknologi ramah lingkungan yang juga dapat digunakan adalah bioremediasi menggunakan mikroalga seperti Chlorella sp. Adanya hubungan sinergis dari bakteri dan mikroalga berpotensi meningkatkan kinerja reduksi senyawa nitrogen pada air limbah organik. Penelitian yang dilakukan pada bulan Juli hingga Agustus 2020 ini, bersifat eksperimental laboratoris menggunakan Rancangan Acak Kelompok, bertujuan untuk mengetahui laju nitrifikasi dan perubahan kadar nitrat, laju pertumbuhan Chlorella sp., serta pengaruh perbedaan perlakuan dan waktu terhadap perubahan kadar nitrat pada air limbah organik dan hubungan Chlorella sp. dengan bakteri nitrifikasi-denitrifikasi. Air limbah yang diambil berasal dari danau Rawa Pening. Hasil penelitian menunjukkan, laju nitrifikasi secara berturut-turut dari yang tertinggi hingga terendah yaitu perlakuan C 0,2 mg NH4-N/liter/jam, diikuti perlakuan B, D dan A masing-masing 0,169, 0,009 dan 0,008 mg NH4-N/liter/jam. Pola pertumbuhan Chlorella sp. mengalami peningkatan hingga hari puncak (hari ke 6) dan menurun hingga hari terakhir. Persentase perubahan kadar nitrat dari awal hingga akhir pengamatan dari yang tertinggi secara berurutan yaitu perlakuan C (1874%), B (1664%), D (200%) dan A (175%). Hasil analisis sidik ragam menunjukkan terdapat perbedaan antara perlakuan terhadap perubahan kadar nitrat (p value <0,05). Hasil Uji DMRT menunjukkan rata-rata perubahan tertinggi adalah perlakuan C, B, D dan A.