The planned advanced processing technology is aerobically using Rotating Biological Contactors (RBC). The research method used was la iterature study, in-depth interviews, and direct observation to the Sari Murni tofu factory to determine the existing conditions of the existing Wastewater Treatment Plant (IPAL), as well as to determine the discharge and characteristics of the tofu wastewater. From the results of observations in the field, it is known that the maximum discharge of tofu wastewater produced every day is 25 m3 with an average BOD parameter value of 200 mg/L. Furthermore, the researchers calculated the required RBC dimensions so that the BOD parameter value could be below standard (<150 mg/L). Based on the calculation results, it can be seen that the surface area of ​​the Rotating Biological Contractors (RBC) required is 450 m2, the number of disks required is 131 pieces, and the length of the Rotating Biological Contractors (RBC) rotor required is 2.5 meters.

This community service activity was carried out by the community service team of the Environmental Engineering Study Program, Faculty of Engineering, Solo Christian University of Technology (UKTS). This activity was carried out in collaboration with the Solo Christian University of Technology (UKTS) with the Tofu Industry Owner "DELE EMAS" as a follow-up to the collaboration contained in the Memorandum of Understanding (MOU) agreed by both parties. This activity was carried out at the tofu and tempe industrial center, Krajan Village, Mojosongo Village, Surakarta City. The form of action for this community service activity is the dissemination of research results from students and lecturers of the Environmental Engineering Study Program that are relevant to the community, with the aim that the learning and research activities that have been carried out can be of real benefit to helping the community. This is a form of integration between learning and research activities into community service activities. The results of this activity are able to provide positive benefits both for higher education institutions, especially lecturers and students, as well as for partner communities.

Currently, cases of hunger and malnutrition as indicators of food insecurity are common in developing countries. Based on the problems that occurred, a collaborative activity was carried out between the Environmental Engineering Study Program at Surakarta Christian University and PT. Bandungan Hydroponic Agrofarm (PT.HAB), and the Waluyo Panti Hospital Surakarta. The implementation of this Cooperation activity is carried out in 3 stages, namely: the preparation stage which includes selecting a topic, the stage for searching for activity participants and the stage for implementing activities in the form of training. One of the efforts that can be made to support the food security program, as well as improve the community's economy and the quality of the environment, especially the air in Surakarta City and other cities in Indonesia is by implementing a hydroponic farming system.

Air limbah merupakan bahan atau sisa hasil kegiatan yang tidak terpakai  yang dapat membawa dampak negatif terhadap lingkungan maupun masyarakat apabila tidak ditangani dengan baik. Kurang tepatnya penanganan limbah domestik akan menyebabkan terganggunya kondisi lingkungan yang disebabkan secara fisika, kimia, dan biologi. Penelitian ini bertujuan untuk melakukan evaluasi terhadap metode pengolahan air limbah di IPAL Semanggi dengan cara menganalisis dan membandingkan antara kualitas air limbah yang diterima (influent) dengan air limbah hasil pengolahan (effluent), dan menghitung efisiensi dari proses pengolahan tersebut.  Baku mutu air limbah domestik, yang dianalisisi  meliputi BOD5, COD, TSS, pH, Amonia, dan Total Coliform, bersasarkan PERMEN LHK No. 68 Tahun 2016 tentang Baku Mutu Air Limbah Domestik. Pengumpulan data primer dan sekunder, observasi lapangan, dan analisis laboratorium terhadap indikator kualitas air limbah merupakan beberapa teknik studi yang digunakan. Hasil penelitian menunjukkan bahwa proses pengolahan air limbah di IPAL Semanggi mampu menurunkan beberapa parameter pencemar air limbah seperti Biological Oxygen Demand (BOD5) dengan efisiensi 78,28%, Chemical Oxygen Demand (COD) dengan efisiensi 37,21%, Total Suspended Solids (TSS ) dengan efisiensi 41,14%, serta mampu menjaga pH effluent tetap stabil (8,06). Selain itu proses pengolahan juga mampu menurunkan Total Coliform air limbah dengan efisiensi 32,01%, namun demikian penurunan Total Coliform saat ini belum memenuhi baku mutu. Sedangkan parameter Amonia effluent justru mengalami peningkatan dibandingkan dengan influennya sehingga parameter Amonia belum mampu memenuhi baku mutu