1 st International Conference Eco-Innovation in Science, Engineering, and Technology Volume 2020 http://dx.doi.org/10.11594/nstp.2020.0515 How to cite: Ramadhany, N. M. M. F., Safrilia, S., Kurniasari, L., Ramadhan, I., Hidayah, E. N., & Farahdhiba, A. U. (2020). Oxidation ditch reactor to remove ammonia and phosphate in tofu wastewater and skin tanning wastewater. 1 st International Conference Eco- Innovation in Science, Engineering, and Technology. NST Proceedings. pages 102-106. doi: 10.11594/ nstp.2020.0515 Conference Paper Oxidation Ditch Reactor to Remove Ammonia and Phosphate in Tofu Wastewater and Skin Tanning Wastewater Ni Made Maya Febriana Ramadhany 1 , Savira Safrialia 2 , Lolita Kurniasari 2 , Iqbal Ramadhan 2 , Euis Nurul Hidayah 2 *, Aulia Ulfa Farahdiba 2 1 Department of Enviromental Science, Universitas Pembangunan Nasional “Veteran” Surabaya, East Java, Indonesia 2 Department of Enviromental Engineering, Universitas Pembangunan Nasional “Veteran” Surabaya, East Java, Indonesia *Corresponding author: ABSTRACT Wastewater containing various types of environmental pollutants, for example, Ammonia and phosphate. Wastewater disposal without proper handling will have an impact on environmental quality degradation, so it is necessary to wastewater treatment using an oxidation ditch reactor with a capacity of 500 liters with an operational volume of 250 liters. The variation treatment in this study was by using tofu wastewater (T) and skin tanning wastewater (PK) with direct sunlight and aeration process with 60 rpm rotation speed for 24 hours x 7 days. The results showed (T) was able to reduce the ammonia concentration by 94.1% from a value of 0.18 mg/L to 0.07 mg/L and a phosphate concentration of 75.3% from a value of 16.05 mg/L to 3.96 mg/L. Whereas the (PK) able to reduce the ammonia con- centration by 94.1% from a value of 0.18 mg/L to 0.07 mg/L and a phosphate concentration of 41.4% from a value of 10.2 mg/L to 5.9 mg/L. Keywords: oxidation ditch reactor, wasterwater, ammonia, phosphate E-mail: euish.t1@upnjatim.ac.id Introduction Every stage in industrial processing generally uses relatively large amounts of water (Gerbens- Leenes et al., 2013). The final process of industrial activities can also produce wastewater which contains many organic compounds such as ammonia and phosphate. Tofu and skin tanning indus- trial wastewater contains high levels of organic materials in the form of protein, carbohydrates, fats, oils, and amino acids (Nurhasan & Pramudyanto, 1997). The presence of these organic com- pounds causes industrial wastewater to contain high ammonia and phosphorus which, if dis- charged into the water without prior treatment, can cause pollution (Husin, 2003;Akpor et al., 2014). Most of the tofu and tanning industry still do not have wastewater treatment, so that industrial entrepreneurs dispose of their wastewater into water bodies which if it exceeds the carrying ca- pacity of the environment it can reduce the quality of the environment (Nurhasan, 1997). Based on these considerations, the oxidation ditch reactor is one way that can be used to treat industrial process wastewater that is environmentally friendly (Alaya et al., 2010). This reactor consists of a series of reactor that aims to purify wastewater so that it is not harmful to the envi- ronment. The advantages of this technology in wastewater treatment are simple construction, easy to design, and can continue to function even though the various types of waste, such as live- stock waste, household waste, and other domestic waste, produce algae containing high protein, which can be utilized for fisheries and maintenance costs are relatively cheap (Abdel-Shafy & Mansour, 2018; Jayashree et al., 2014).