Evaluasi Instalasi Pengolahan Air Limbah (Ipal) Limbah Cair Industri Tepung Tapioka Pt. Sari Tani Sumatera, Serdang Bedagai

Abstract

Tapioca flour industry wastewater is one type of industrial wastewater that can be said to be as dangerous as the palm oil industry wastewater. The tapioca flour industry in North Sumatra is better known as located in Belawan. In Serdang Bedagai, there are 2 (two) tapioca flour producing industries, but only Sari Tani Sumatera Company has been operating actively since the 1990s until now. From the results of interview to the society who lived in the left side of Sari Tani Sumatera Company, it was found that the wastewater produced by tapioca flour turned out to be disturbing their activities which marked by the death of fish in the river and the vegetables that they planted, the river’s water could not be used as usual so use automatic pump machine as a substitute, as well as the odor from sewage smells bad clearly. Meanwhile, Sari Tani Sumatera Company is still using stabilization pond system with walls and the ground/bottom are covered by soil only and in an open condition. The total area of WWTP in Sari Tani Sumatera Company is 2 hectares out of a total of 6 hectares, and measuring 0.1 ha per pond. Even so, Sari Tani Sumatra Company wants to commit more deeply to improve the quality of waste disposal, including wastewater for the future. Therefore, an evaluation process was carried out at the WWTP of Sari Tani Sumatera Company. The discharge of wastewater obtained ranges from 428-500 m3 / day. From the identification of pond types based on initial allegations, it turns out there are 3 initial ponds with low rate aerobic types, 1 facultative pond type, 1 high rate aerobic pond type, and 4 final maturation ponds with depths of 4-5 meters. It turns out that after being re-monitored, it turns out that 3 types of low-rate aerobic ponds in fact work anaerobically to produce methane gas and CO2. In addition, the outlet data shows that the value of Total Coliform = 1490 MPN / 100 ml. BOD = 210 mg / L, COD = 469 mg / L, TSS = 74 mg / L, pH = 7.38 and Cyanide = 0.47 mg / L. After calculating the depth of the pond based on the initial design and existing, it turns out that there is a reduction in depth due to the accumulation of sludge at the bottom of the pond and ultimately affects the detention time as well. The efficiency pond is calculated based on the mean of the removal eficiency of each parameter (except pH) until an alternative data calculation of the parameter test is also obtained in which all values of the parameter levels fulfill the quality standard (different from the data outlet). Furthermore, the loading rate surface of each pond is calculated with a comparison of detention time, depth, and loading rate surface with the stabilization pond design criteria can be determined in the evaluation where the pond needs to be reviewed. Based on the results obtained, pond 3 is actually more reconsidered and Pond 4 becomes a stumbling block because it participates in increasing the level of parameters even though the detention time and depth still fulfill the design criteria. Nevertheless, pond 5 to Pond 9 turned out to still fulfill the design criteria even though the available land area was limited than expected. Therefore, the main suggestions and recommendations are to built cement on the walls and bottom of the pond, to slur the sludge at the bottom of the pond and moss in the drain to the Rambung river, to change the pond system 1 to. pond 3 becomes anaerobic pond and pond 4 becomes anaerobicfacultative (or there are another suggestions for fixing improvement), and it is necessary to checking wastewater routine internally at least once a month.

Limbah cair industri tepung tapioka adalah salah satu jenis limbah cair industri yang bisa dikatakan sama bahayanya dengan limbah cair industri kelapa sawit. Industri tepung tapioka di Sumatera Utara lebih dikenal berlokasi di daerah Belawan. Di daerah Serdang Bedagai, ada 2 (dua) industri penghasil tepung tapioka, namun hanya PT Sari Tani Sumatera yang masih aktif beroperasi sejak 1990an hingga sekarang. Dari hasil kuesioner terhadap masyarakat di yang tinggal di sebelah kiri PT Sari Tani Sumatera didapat bahwa limbah cair industri tepung tapioka yang dihasilkan ternyata mengganggu aktivitas warga yang ditandai dengan matinya ikan di sungai dan sayur mayur yang mereka tanam, air sungai tidak bisa dipakai seperti biasa sehingga menggunakan sumur bor sebagai pengganti, serta bau dari limbah tercium jelas. Sementara itu, PT Sari Tani Sumatera masih menggunakan sistem kolam stabilisasi dengan berdinding dan beralaskan tanah serta dalam kondisi terbuka. Luas lahan IPAL PT Sari Tani Sumatera adalah 2 Ha dari total 6 Ha, dan berukuran 0,1 ha per kolam. Meskipun begitu, PT Sari Tani Sumatera mau berkomitmen lebih dalam lagi untuk memperbaiki kualitas pembuangan limbah, termasuk limbah cairnya untuk masa yang akan datang. Maka dari itu, dilakukan proses evaluasi pada IPAL PT Sari Tani Sumatera. Debit air limbah yang diperoleh berkisar 428-500 m3/hari. Dari identifikasi jenis kolam berdasarkan dugaan awal, ternyata ada 3 kolam awal jenis aerobic low rate, 1 kolam jenis fakultatif, 1 kolam jenis aerobic high rate, dan 4 kolam akhir jenis maturasi dengan kedalaman kolam berukuran 4-5 meter. Ternyata setelah dipantau ulang, ternyata 3 kolam jenis aerobic low rate tersebut nyatanya bekerja secara anaerobik hingga menghasilkan gas metana dan CO2. Selain itu, data outlet menunjukkan bahwa nilai Total Coliform= 1490 MPN/100 ml. BOD= 210 mg/L, COD= 469 mg/L, TSS = 74 mg/L, pH= 7,38 dan Sianida= 0,47 mg/L. Setelah melakukan perhitungan kedalaman kolam berdasarkan desain awal dan eksisting, ternyata terjadi pengurangan kedalaman akibat penumpukkan lumpur di dasar kolam dan akhirnya memengaruhi waktu detensinya juga. Efisiensi kolam dihitung berdasarkan ratarata removal eficiency setiap parameter (kecuali pH) hingga diperoleh juga data alternatif perhitungan uji parameter yang nyatanya semua nilai kadar parameter memenuhi baku mutu (berbeda dengan data outlet). Selanjutnya dihitung loading rate surface setiap kolam dan dilakukan perbandingan waktu detensi, kedalaman, dan loading rate surface dengan kriteria desain kolam stabilisasi untuk bisa ditetapkan evaluasi di bagian mana kolam tersebut perlu ditinjau ulang. Berdasarkan hasil yang diperoleh, kolam 3 yang justru lebih diperhatikan ulang dan Kolam 4 yang jadi batu sandungan karena ikut serta menaikkan kadar parameter meskipun waktu detensi dan kedalaman masih memenuhi kriteria desain. Walaupun demikian, kolam 5 s.d. Kolam 9 ternyata masih memenuhi kriteria desain meskipun luas lahan yang tersedia terbatas dari yang diharapkan. Maka dari itu, saran dan rekomendasi utamanya adalah dengan memasang semen di dinding dan alas kolam, melakukan pengurugan lumpur di dasar kolam dan lumut di saluran pembuangan menuju sungai Rambung, mengubah sistem kolam 1 s.d. kolam 3 menjadi kolam anaerob dan kolam 4 menjadi anaerob-fakultatif (atau ada saran perbaikan lainnya), serta perlu melakukan pemeriksaan air limbah secara internal dengan rutin minimal 1 kali setiap bulan.