Household sewage treatment in Surakarta City depends on the performance of the available domestic wastewater treatment plants (IPAL), including Pucangsawit IPAL, Semanggi IPAL, Mojosongo IPAL, and UNS IPAL. Each of these IPAL’s serves a specific area, such as the UNS IPAL which serves the UNS area and its surroundings, the Mojosongo IPAL which is in charge of the North Area of Surakarta, the Semanggi IPAL which takes care of the South Area of Surakarta, and the Pucangsawit IPAL which serves the Central Area of Surakarta City. This research aimed at the effectiveness of the performance and development plan of each IPAL in the next 20 years. This research used descriptive qualitative and quantitative analysis methods. Qualitative descriptive analysis was conducted by observing the existing condition of IPAL Komunal in the research location. Quantitative descriptive analysis in this study was carried out by testing samples at the inlet, aeration, and outlet points of the IPAL. Based on the quality standards of the Minister of Environment and Forestry Regulation number P 68 of 2016, each IPAL. UNS IPAL is 47.27% for BOD, 73.81% for COD, 76.36% for TSS. Mojosongo IPAL is 88.71% for BOD, 76.50% for COD, 78.57% for TSS. Pucangsawit IPAL was 91.88% for BOD, 83.20% for COD, 74.82% for TSS. Semanggi IPAL is 20.45% for BOD, 69.95% for COD, 69.05% for TSS. Alternative development at the IPAL that can be done to prepare for the next 20 years is to increase the volume in the initial settling basin, aerobic biofilter basin, and also the final settling basin. 
 

This study aims to analyze the impact of administering commercial probiotic bacteria on the wastewater from tofu industries on changes in Bio-logical Oxygen Demand (BOD) and Dissolved Oxygen (DO) levels. Tofu industry wastewater is known to have high BOD and low DO levels, which pose a potential environmental pollution risk. This study used a pure experimental method with variables including the ratio of tofu industry wastewater to commercial probiotics (1:1, 1:2, 1:3) with an incubation interval of 8 hours. The results showed that the administration of commercial probiotic bacteria significantly reduced BOD levels and increased DO levels in the wastewater. The 1:3 ratio of tofu industry wastewater to commercial probiotics showed the most optimal effect in increasing DO and decreasing BOD. An incubation time of 32 hours showed the most optimal effect in increasing DO and decreasing BOD. The 1:3 volume ratio between tofu wastewater and probiotics (25% tofu wastewater and 75% probiotics) proved to be the most effective, with the highest DO increase of 2.51 mg/L and the largest BOD decrease of 144.20 mg/L. In addition, incubation time also had a significant effect, the longer the incubation time, the more optimal the probiotic activity in reducing BOD levels and increasing DO levels. The conclusion of this study is that the administration of commercial probiotic bacteria at a 1:3 ratio and an incubation time of 32 hours is an effective way to improve the quality of tofu industry wastewater.

Butuh Village is one of the villages in Butuh District,  Purworejo Regency, Central Jawa Province. The villages’s need for awareness of adequate sanitation is still quite low. This can be proven by the fact that there are still many houses that do not have adequate domestik waste processing infrastructure. AS we know, if we dispose of domestik waste in the form of grey water and black water directly into the environment without a good waste processing system, it will pollute the environmen. The aim of this design is to determine the domestik wastewater treatment bulding in Butuh village using the hierarchical method.The final calculation using the hierarchical method resulted in thr selected domestic wastewater treatment being the Anaerbic Buffled Reactor (ABR) using 4 parameters in the form of maintenance operatinal cost, land area used, construction costs and removal efficiency. The Anaerobic Buffled Reactor (ABR) is planned to have 5 compartments with a BOD removal efficiency of 84%, construction cost of Rp. 67.899.607, the land area required is 45 m2, and operational costs are Rp. 2.605.281 and maintenance is relatively easy.