The Treatment of Nata de Coco Processing Wastewater Using Anaerobic Bio-Filter Muhammad F. Radityo, Yuli Pratiwi*, and Sri Hastutiningrum Abstract—Liquid waste of Nata de Coco industry is acidic and contains high organic matter, hence, it requires proper treatment before being released into the environment. This research aims to determine the quality of Nata de Coco industrial wastewater and the toxicity of liquid waste (LC 50 96 hours) to goldfish bio-indicators before and after being treated with anaerobic bio-filters. The research phase includes: 1) Liquid waste treatment using anaerobic bio-filters with wasp nest media, 2) determination of optimal processing time duration with variations of 48, 72, and 96 hours, 3) toxicity tests before and after processing such as acclimatization, preliminary, and actual tests, and 4) analysis of research data using probit analysis and linear regression. The results showed that biochemical oxygen demand (BOD) and COD (chemical oxygen demand) values are higher than standard values according to the Regulation of the Minister of Environment of Indonesia Number 5 of 2014, while the pH is lower than the standard value. The optimal processing time duration is 48 hours with a decreased percentage of BOD, COD, and pH of 53.24%, 30.37%, and 46.15%, respectively. The actual LC 50 value of 96 hours of liquid waste before and after treatment is 28.20% and 47.21%, respectively. Index Terms—Anaerobic bio-filter, liquid waste, Nata de Coco, toxicity I. INTRODUCTION One of the benefits of the Nata de Coco industry is its ability to increase the selling value of coconut water used as a raw material in the production process. However, this industry also produces liquid waste with acidic characteristics and high organic matter content. This means when this wastewater is not treated properly, it can cause environmental pollution and consequently disrupt the life of organisms. The high content of organic matter in wastewater can decrease dissolved oxygen levels in the water, thereby impacting the life and balance of organisms, specifically aquatic biota. According to Regulation of Minister of Environment of Indonesia number 5 the year 2014 [1], wastewater quality from the Nata de Coco industry has to follow the standard, as shown in Table I. Therefore, the Nata de Coco wastewater must meet the Indonesian Standard before being released into the environment. The liquid waste quality can be enhanced by performing biological and physicochemical treatment [2]. The biological method can be performed either by aerobic or anaerobic treatment, depending on biochemical oxygen demand (BOD). In general, wastewater with BOD below and above 300 mg/L can be treated effectively using aerobic and anaerobic Manuscript received May 16, 2022; revised July 7, 2022; accepted September 9, 2022. The authors are with the Department of Environmental Engineering, Faculty of Applied Science, Institut Sains & Teknologi AKPRIND, Indonesia. *Correspondence: yuli_pratiwi@akprind.ac.id (Y.P.) systems, respectively [3]. TABLE I: WASTEWATER STANDARD FOR COCONUT INDUSTRY [1] Parameter Maximum [mg/L] [kg/ton] BOD 75 1.1 COD 150 2.2 TSS 100 1.5 Fatty acid 15 0.2 pH 6–9 Wastewater 15 m 3 /ton product Several research have been conducted on liquid waste treatment. Khurshid et al. [4] utilized tea waste biochar as an adsorbent filter for wastewater treatment. Maximum COD (Chemical Oxygen Demand) removal efficiencies were found to be 89.35 ± 0.5% and 95.5 ± 0.5% for single and combined modified biochar, respectively. Sela et al. [5] and Beyan et al. [6] treated liquid waste in the textile industry. Sela et al. [5] processed the cephalothorax and abdomen shell of the prawn to obtain chitosan, which is used to reduce the value of BOD and COD of wastewater of textile industry. These research showed that the reduction rate of BOD and COD was significant and in the acceptable range of discharge water quality. Meanwhile, Beyan et al. [6] used activated sugarcane bagasse as an adsorbent for reducing BOD and COD of textile effluent at rate constants of 0.028 and 0.0274 mg/L·min -1 , respectively. Other biomaterials as an adsorbent of liquid waste treatment were Carica papaya leaf MgO-nano powders [7], Avacado peel carbon [8], and activated carbon [9]. Oladipo et al. [7] evaluated the COD and BOD reduction efficiency of MgO-nano powder for a raw tannery wastewater. The result showed that COD reduced from 2725.9 mg/L to126.5 mg/L and BOD decreased from 1899.5 mg/L to 104.5 mg/L. Devi et al [8] found that the maximum percentage reduction of COD and BOD concentration under optimum operating conditions using Avacado peel carbon was 98.20% and 99.18%, respectively. Meanwhile, Hami et al. [9] stated that for dosages of activated carbon in the range of 50–150 mg/L, the removal efficiencies for BOD increased from 27–70% to 76–94%, while for COD it rose from 16–64% to 72–92.5%. Recently, Pratiwi et al. [10] used silica sand as a filter for wastewater treatment in a slaughterhouse. Organic based on nanomaterial has obtained attention as a promising adsorbent for wastewater treatment [11] due to the low cost and large surface area to volume ratio [12]. The large surface area to volume ratio at the nano level improved the adsorption capacity and made it better adsorbing materials than conventional ones. In addition, the small size and active surface with high porosity of the nanomaterial enable them to adsorb, separate, and remove contaminated materials from the water [13–15]. Organic nanomaterial adsorbents used in water treatment are nanoclay for organic compounds and heavy metals, while micelles are used for International Journal of Environmental Science and Development, Vol. 14, No. 2, April 2023 106 doi: 10.18178/ijesd.2023.14.2.1421