Abstract
One of the relatively affordable and safe waste treatment is biological treatment by utilising certain plants as biofilters. The water lettuce (Pistia stratiotes L.) is an aquatic plant that is usually considered a weed by the community. These plants can be used to absorb toxic elements in wastewater. The purpose of this study was to analyse the relationship between Pistia stratiotes L. and the decrease in the organic matter content of fishery processing wastewater. The research method involved varying the effectiveness of the relationship between the bacteria and the water lettuce, the cover rate of the water slide plants and measuring water quality. Water quality measurements include: analysis of BOD5, COD, TSS, pH and temperature. Data analysis with regression and correlation tests using SPSS 28 software. In this study, the density of Pistia stratiotes L. used was 0 %, 25 %, 50 %, 75 % and 100 %. Based on the results, it can be concluded that the effectiveness of the Pistia stratiotes L. in reducing levels of BOD5, COD and TSS is highest at a density of 100 % with the effectiveness values of each 23.7 mg/L, 58.7 mg/L and 2.67 mg/L.