Environmental Science
K. Seethong; K. Chunkao; N. Dampin; W. Wararam
Abstract
BACKGROUND AND OBJECTIVES: The increasing population and urban growth have led to a higher demand for water in various sectors, resulting in a significant amount of wastewater. Constructed wetlands mimic natural wetlands, using the interaction between plants, soil, and microorganisms to treat wastewater ...
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BACKGROUND AND OBJECTIVES: The increasing population and urban growth have led to a higher demand for water in various sectors, resulting in a significant amount of wastewater. Constructed wetlands mimic natural wetlands, using the interaction between plants, soil, and microorganisms to treat wastewater efficiently. This study assesses the diversity, species composition, and distribution of benthic organisms in a community wastewater-filter grass system and explores the relationship between water quality and benthos.METHODS: Water samples were collected from plant plots between December 2021 and March 2022. On-site measurements included temperature, dissolved oxygen, salinity, and pH, whereas laboratory analysis encompassed the biochemical oxygen demand, ammonia, nitrate, total phosphorus, orthophosphate, and suspended solids. Soil samples were taken before and during planting at 2-week intervals, evaluating organic matter, pH, electrical conductivity, salinity, phosphorus, potassium, calcium, magnesium, and plant growth indicators. Benthos sampling involved polyvinyl chloride pipe cores at a depth of 5 cm from the soil surface. Statistical tests were performed to analyze the water quality data.FINDINGS: The study observed a decrease in Chironomid abundance in both constructed wetland systems, indicating their effectiveness in treating wastewater. A comparison of system types revealed that the 5-day detention–2-day dry release system exhibited higher Chironomid abundance than the continuous flow system, and the biological oxygen demand maximum decreasing rate was 95%. The ammonia and nitrate maximum decreasing rates were 97% and 94%, respectively, indicating greater wastewater-treatment efficiency. The study also identified diverse benthic organisms, particularly chironomids, as bioindicators for assessing wastewater conditions.CONCLUSION: The continuous flow system and the 5-day detention–2-day dry release system of constructed wetlands can reduce the organic compounds and increase the oxygen levels in the plant plots. The interaction among plants, soil, and microorganisms is critical in wastewater treatment. In addition, the study highlighted the diversity and abundance of benthic organisms, particularly chironomids, which were more prominent in the continuous flow system. Consequently, the 5-day detention–2-day dry release system was more efficient in treating wastewater than the continuous flow system.
F.M. Muvea; G.M. Ogendi; S.O. Omondi
Abstract
The use of constructed wetlands for purifying pre-treated wastewater is a cost effective technology that has been found to be more appropriate for many developing countries. The technology is also environmentally friendly with the wetlands being habitats for many water birds and other aquatic organisms. ...
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The use of constructed wetlands for purifying pre-treated wastewater is a cost effective technology that has been found to be more appropriate for many developing countries. The technology is also environmentally friendly with the wetlands being habitats for many water birds and other aquatic organisms. This study assessed nutrient removal efficiency of two floating macrophytes (Lemna minor and Azolla pinnata). The data generated was analyzed using both descriptive and inferential statistics. The significance level was maintained at 0.05. The results showed that the wastewater physicochemical parameters did not vary during the study period. The concentrations of nitrites and nitrates increased over the experimental period in all the treatments (Azolla pinnata, Lemna minor and control), and the increase between the sampling occasions was statistically significant for the two nutrients (Nitrates: F=24.78, P= 0.00; Nitrates: F=198.26, P= 0.00). To the contrary, in all the treatments the concentrations of ammonia, total phosphorous, soluble reactive phosphorous and total nitrogen, decreased over the experimental period. The decrease in concentration for these nutrients between the sampling occasions was statistically significant (ammonia: F=195.57, p= 0.00; total phosphorous: F= 56.50, p= 0.00; soluble reactive phosphorous: F= 37.11, p= 0.00; total phosphorous: F= 104.025, p= 0.00). Azolla pinnata proved to be better than Lemna minor in the uptake of the nutrients particularly for the soluble reactive phosphorous (F= 35.18, P= 0.044). We conclude that the two macrophytes are good for wastewater treatment. It is recommended introduction and/or multiplication of Azolla pinnata in the constructed wetlands meant for wastewater treatment especially within the tropics.
