1,2,3,4Environmental Engineering Departement, National Institute of Technology in Malang
Abstract
Domestic wastewater is main pollutant for their receiving river. Domestic wastewater treatment communal has built for reducing the pollutant. These communal wastewater treatment plant (CWWTP) most located at the riverbank for convenience to discharge. The effluent of CWWTP has not monitored regularly so the treatment performance of CWWT is unknown. Tlogomas CWWTP located at Tlogomas gang 8 Malang city East Java managed by Kelompok Sanitasi Masyarakat (KSM) Panca Murti. Tlogomas has been operated since 2011 and it service 96 households or 460 peoples. The operating capacity exceed the desain capacity of 350 peoples. Tlogomas CWWTP is an anaerobic treatment which use sedimentation, anaerobic baffled reactor and anaerobic filter as their unit treatment.
This research was aimed to know the quality of effluent Tlogomas CWWTP and their treatment performance. To determine its effect, we followed the Minister of Environment and Forestry regulations No. 68/2016 parameters for wastewater quality standard such as Biochemical Oxygen Demand (BOD) and Chemical Oxygen Demand (COD) to know the actual quality of the wastewater. In addition, this research also tested the concentration of Nitrate (NO3) and Phosphate (PO4) to know nutrient characteristics of the effluent. We sampled CWWTP effluent on 17 May, 7 July, 12 July and 20 July in 2022.
Sampling method we used on this research was based on Standar Nasional Indonesia (SNI) 6989.59:2008. Besides, for determining the effluent quality, we used the laboratory analysis based on SNI 6989.2.2019 for COD, APHA 5210 B.2017 for BOD, Q1/LKA/65 for NO3 and SNI 6989-31:2021 for PO4.
The evaluation result of Tlogomas CWWTP^s effluent quality showed below. The concentration of COD consecutively 584.5 mg/L- 120.5 mg/L- 285.9 mg/L- 194.6 mg/L so it was exceeding the wastewater quality standard which should less than 100 mg/L. For the concentration of BOD, 1 of the samples shows the good result, which still on the wastewater quality standard which should less than 30 mg/L (28.85 mg/L). But for the another, the values were not (206.6 mg/L- 91.44 mg/L- 62.73 mg/L). The value of NO3 concentration respectively 5.323 mg/L- 10.63 mg/L- 11.65 mg/L- 8.919 mg/L. PO4 concentration are 13.23 mg/L- 13.7 mg/L- 21.45 mg/L- 9.115 mg/L. From the data above, the effluent of Tlogomas CWWTP still contain high organic and nutrient. Effluent discharge to riverbank potentially contaminanted the soil and river. The high organic contains in effluent Tlogomas WWTP caused by hydraulic loading (38.22 m3/m2.day) which exceed the design (27.87 m3/m2.day). So, the organic loading also exceeding the design where the value showed respectively 2.2 kg/m2.day- 0.31 kg/m2.day- 0,97 kg/m2.day- 0.67 kg/m2.day. Furthermore, low treatment performance also caused by the maintenance that not routinely conducted. This caused treatment capacity reduced from the sludge accumulation. Recommendation for treatment is sludging drain to extend the capacity of Tlogomas CWWTP. Another recommendation is extending the capacity of CWWTP with adding the unit of treatment
