Abstract
Continued entries of liquid wastes generated by tofu industries into nearby rivers might deteriorate the water quality if disposed of without prior treatments. The research objectives were to determine the liquid waste quality from tofu productions near Parangan River (Magelang, Indonesia), assess the river water quality and investigate the effects of the liquid waste on pollution load and water quality status. With this information, the research can help determine pollutant load allocation in the river and provide the basis for formulating water quality management policies if it is not contaminated or pollution controls if otherwise. This research employed purposive sampling, direct measurements in the field, laboratory tests, descriptive-comparative analysis, mass balance and pollution index method. The results showed that the pH, temperature, COD, BOD, TSS and ammonia levels of the liquid wastes had surpassed their maximum permissible levels. Similarly, the river’s COD, BOD and ammonia contents did not meet the water quality standards. With BOD, a pollution load indicator, exceeding the total maximum daily load, the water quality statuses at monitoring points S2, S3 and S4 were categorised into slightly polluted. It means that the liquid waste generated by the tofu industries has detrimental effects on the water quality of the Parangan River.
Highlights
Water is a natural resource that is utilised vastly to meet the basic needs of living organisms worldwide
Four tofu producers drained their waste byproducts into fish ponds as treatment facilities before the treated waste flowed into the Parangan River through the pond outlets
Based on the interview results, the latter was dominant because there was no space left to build the wastewater treatment plant (WWTP) and the presumption that the liquid waste would not contaminate the river and that after all this water body would continuously flow
Summary
Water is a natural resource that is utilised vastly to meet the basic needs of living organisms worldwide. In Magelang District, Indonesia, tofu industries are small-scale enterprises that have yet to incorporate liquid waste treatment prior to disposal into production costs. This liquid waste contains high pollutants and suspended and dissolved solids that experience physical, chemical and biological changes [3]. With these characteristics, it will substantially reduce the water quality if discarded directly into the river and lead to decreased productivity, environmental capacity and carrying capacity of the river water [23]
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