Besides being useful for making fermented foods such as tempeh, soy sauce, and tape, mushrooms can be used to treat wastewater. They have the ability to decompose organic compounds in waste, greater than bacteria, especially in decomposing polymers with complex bonds such as cellulose, hemicellulose, and lignin.
The fungi contain several extracellular enzymes that are able to decompose complex compounds through nonspecific oxidation reactions. Therefore, mushrooms can function as decomposers of organic compounds in wastewater with low pH. This is very useful because in these conditions, bacterial growth is inhibited so the decomposition process is inhibited as well. In this condition, the fungi can develop quickly and use nutrients used by pathogens to survive, so the pathogens will disappear.
Furthermore, the fungi can denitrify faster than bacteria. This denitrification process is useful for removing nitrite and nitrate compounds so that the processed wastewater is free from both compounds causing fish death and uncontrolled algae growth.
Another advantage of fungi compared to bacteria is the ability to survive in low pH conditions, limited nutrition, and low temperatures. Moreover, mushrooms produce antibiotics that play a role in reducing the growth of bacteria and pathogens, and increasing the breakdown of organic matter. Research showed that the fungus Aspergillus niger and Penicillium corylophilum can reduce water pollution parameters better than bacteria.
Based on these characteristics, a study was conducted to assess the effectiveness of mushrooms in treating domestic wastewater containing liquid cleaning agents. In this study, the fungi used were Aspergillus niger, Aspergillus sp., and Fusarium solani because Aspergillus niger dominated 98 percent of microorganisms in wastewater treatment plants, while Aspergillus sp. and Fusarium solani are found in wastewater treatment deposits.
Reactor C and D Added with Mushrooms
There are 4 reactors tested in this study. The reactors B and D were added with detergent while reactors A and C did not. The addition of detergent affects the acidity in the reactor so that reactor B and D have a pH of 2 due to the HCl content in the detergent. Then, reactors C and D were added with fungus isolate, while reactors A and B did not.
The effectiveness of mushrooms in treating wastewater can be seen from the performance of organic matter removal, the phosphate and ammonia. This parameter was chosen because both are found in domestic wastewater. The main source of phosphate is detergent, while the main sources of ammonia are urine and kitchen waste.
As a result, phosphate concentrations in reactor A and C decreased from the first day to the 18th. The percentage of phosphate removal is 69.6 percent in reactor A and 70.8 percent in reactor C. While the percentage of phosphate removal in reactors B and D fluctuates every day. In contrast to reactors A and C, reactor B only removes phosphate by 14.6 percent while reactor D by 16.5 percent because the reactor acidity affects the function of the fungus in breaking down organic matter. The percentage of reactor D removal began to increase since the 4th day. It proves that mushroom function as decomposers of organic matter in wastewater with low pH condition, where bacterial growth is inhibited.
The percentage of ammonia removal at reactor A was 89.5 percent and at reactor C 90.2 percent. After the 7th day, the percentage tends to be stable and the percentage of the removal for the two reactors is almost the same, 98.8 percent and 99.9 percent. An increase in the percentage of ammonia removal to 99 percent due to the role of fungi as heterotrophic microorganisms that can help the process of nitrification. Through this process, ammonia is converted to nitrate and nitrite so that the concentration of ammonia in the reactor decreases. In addition, the fungi carry out a denitrification process reducing the amount of nitrate and nitrite so that the level of water pollution is reduced.
Meanwhile, reactor B and D only removed ammonia by 32.2 percent and 30.8 percent. In this case, the addition of fungi in reactor D had little effect on the removal of ammonia under acidic conditions, but both reactors still had the ability to reduce the concentration of ammonia. The presence of fungi is useful for the continuation of the nitrification process in acidic conditions, where autotrophic microorganisms playing a role in nitrification do not work.
From this study, it can be concluded that the reactor with and without the addition of mushrooms has the same percentage of phosphate and ammonia removal. The addition of mushrooms to treat domestic wastewater has no significant impact on reducing ammonia and phosphate levels. However, acidic conditions affect the performance of microorganisms in breaking down wastewater because not all microorganisms can survive under acidic conditions. (*)
Author: Nurina Fitriani
Details of the research available at:
Isnadina, D. R., Fitriani, N., Citrasari , N., & Soegianto, A. (2019). Effectiveness of fungi to remove nitrogen and phosphorus in domestic waste water. Pollution Research, 59-64.