CSA PAKISTAN

Floating wetland is an emerging technique for the sustainable treatment of municipal wastewater

Irfan Haidri, Muhammad Qasim, Memoona

Department of Environmental Sciences

Government College University Faisalabad

Abstract:

Floating wetland treatment (FWs) is an efficient and environmentally friendly technology for the treatment of municipal wastewater by adopting phytoremediation. FWs consist of a platform that floats and is connected to the pond or lake’s bottom and is composed of a buoyant material, like polystyrene or recycled plastic. For the purpose of removing nutrients and heavy metals from wastewater, several plants, including cattails, bulrushes, sedges, water hyacinth, duckweed, and water lettuce, are frequently employed in FWs. The choice of plants is influenced by local environmental factors and problems with water quality. To maximize the effectiveness of FWs and create new plant species for FW use, more study is required.

Introduction:

Municipal wastewater treatment is a vital step in ensuring the environment is not harmed when wastewater is released (Daud et al., 2018). Traditional wastewater treatment methods, however, take a lot of energy and can increase greenhouse gas emissions. Floating wetlands (FWs) are gaining popularity as a sustainable and economical method of treating sewage from cities. FWs are man-made floating islands covered in a covering of vegetation that use phytoremediation to remediate wastewater (Alnaser et al., 2022). Throughout the treatment process, plants are essential because they take in and digest the contaminants in the wastewater (Akram et al., 2020).

In this blog, we will discuss the design, functionality, benefits, and limitations of the current research on floating wetlands for treating municipal wastewater.

Design and Operation:

FWs comprised of a platform that floats and is attached to the pond or lake’s bottom and is composed of a buoyant material, like polystyrene or recycled plastic. The soil or pebbles is then spread over the platform, providing a habitat for the flora (Biswas et al., 2022). Typically, a variety of wetland plants including cattails, bulrushes, and sedges make up the vegetation. With the process of phytoremediation, FWs operate by eliminating contaminants from wastewater. Although the microorganisms in the soil transform the pollutants into harmless molecules, the roots of the plants ingest and metabolize the pollutants (Shahid et al., 2020). The environment is then supplied with the purified water. The price of installing FWs might vary based on a number of elements, including the system’s size, the plants utilized, the type of water body, and the project’s location. Installing FWs typically costs more than establishing standard wastewater treatment systems like lagoon or aeration tank systems (Stefanakis, 2019). The cheaper running and maintenance expenses of FWs, however, can eventually make up for the higher installation costs. The size of the system and the level of architectural complexity can affect how long it takes to install FWs. Because FWs are modular and easy to construct, they often need less time to install than standard wastewater treatment systems (Likitswat et al., 2023; Stefanakis, 2020).

Types of Plants Used in floating wetlands:

Cattails are among the most often utilized plants in FWs because of their aptitude for absorbing and metabolizing fertilizers like nitrogen and phosphorus(Wei et al., 2020). They are also aesthetically beautiful and offer homes for aquatic life. According to U.S. research, cattails in FWs can reduce the amount of nutrients in wastewater by up to 99% (Jain et al., 2020). Bulrushes are also frequently used for municipal wastewater treatment because of their capacity to absorb nutrients and heavy metals from wastewater (Shahid et al., 2018). They can also be employed to strengthen shorelines and offer habitat for aquatic creatures. According to a Chinese study, bulrushes in FWs can lower the levels of nutrients in urban wastewater by as much as 82% (Vymazal, 2014). Plant-like sedges has a greater capacity to absorb and digest nutrients and heavy metals, and are frequently employed in FWs (Nuruzzaman et al., 2022). They can be applied in FWs in many locations and are tolerant of a broad range of environmental circumstances. Water hyacinth, a plant with a rapid development rate, is utilized in FWs to treat wastewater. It is very good at removing nutrients from wastewater, like phosphorus and nitrogen. However, water hyacinth may also grow in stress conditions, therefore it must be managed properly to stop it from colonization new bodies of water (Sun et al., 2021). Little floating plants called duckweed are applied in FWs to clean wastewater. It is very effective at eliminating nutrients from wastewater, like nitrogen and phosphorus. Duckweed is a plant that grows quickly and can be collected for biofuel or to be utilized as animal feed. A floating plant called water lettuce is applied in FWs to clean wastewater (Arivukkarasu and Sathyanathan, 2022). It is very good at removing nutrients from wastewater, like nitrogen and phosphorus. In addition to being attractive, water lettuce can serve as a home for aquatic life (Ali et al., 2020).

Advantages:

Compared to conventional wastewater treatment techniques, FWs have a number of advantages. They are inexpensive, simple to install, and require little management (Stefanakis, 2020). FWs also have a smaller carbon footprint than conventional wastewater treatment methods because they don’t need energy-consuming procedures like aeration. FWs can also offer further advantages like better aquatic life habitats and water quality (Zhu et al., 2021). Due to their ability to blend in with their surroundings, FWs can also be used to treat wastewater in urban areas in a way that is both environmentally friendly and aesthetically beautiful (Zhu et al., 2021; Stefanakis, 2020).

Challenges:

FWs confront a number of obstacles in addition to their tremendous benefits. Performance inconsistency is one of the key obstacles. Environmental factors including temperatures, light, and quality of water have a significant impact on FWs (Herrera, 2019). The effectiveness of the treatment process and the growth of the vegetation can both be impacted by changes in these factors. The small range of plant species that can be employed in FWs presents another difficulty. The variety of pollutants that can be cured is constrained by the fact that only a few number of wetland plants are appropriate for FWs (Chowdhury and Moore, 2017).

Conclusion:

FWs are efficient and suitable technology for the treatment of municipal wastewater treatment because it is environment-friendly and economically sensible.  They are more successful at eliminating contaminants from wastewater than conventional wastewater treatment methods and have a number of advantages over them. However, FWs also encounter a number of difficulties, including performance unpredictability and a lack of plant species. To increase the effectiveness and dependability of FWs as a wastewater treatment technique, more study is required.

Reference

Akram, A., N. Tara, M.A. Khan, S.A. Abbasi, M. Irfan, M. Arslan and M. Afzal. 2020. Enhanced remediation of Cr6+ in bacterial‐assisted floating wetlands. Water Environ. J. 34:970–978.

Ali, S., Z. Abbas, M. Rizwan, I.E. Zaheer, İ. Yavaş, A. Ünay, M.M. Abdel-Daim, M. Bin-Jumah, M. Hasanuzzaman and D. Kalderis. 2020. Application of floating aquatic plants in phytoremediation of heavy metals polluted water: A review. Sustainability 12:1927.

Alnaser, Z.H.A., S.R. Chowdhury and S.A. Razzak. 2022. Constructed Wetlands for Wastewater Treatment in Saudi Arabia: Opportunities and Sustainability. Arab. J. Sci. Eng. 1–17.

Arivukkarasu, D. and R. Sathyanathan. 2022. Floating wetland treatment an ecological approach for the treatment of water and wastewater–A review. Mater. Today Proc.

Biswas, J.K., M. Mondal, V. Kumar, A. Bhatnagar, S. Biswas and M. Vithanage. 2022. Nature-inspired ecotechnological approaches toward recycling and recovery of resources from wastewater. Integrated Environmental Technologies for Wastewater Treatment and Sustainable Development. Elsevier. pp.101–145.

Chowdhury, R.B. and G.A. Moore. 2017. Floating agriculture: a potential cleaner production technique for climate change adaptation and sustainable community development in Bangladesh. J. Clean. Prod. 150:371–389.

Daud, M.K., H. Rizvi, M.F. Akram, S. Ali, M. Rizwan, M. Nafees and Z.S. Jin. 2018. Review of upflow anaerobic sludge blanket reactor technology: effect of different parameters and developments for domestic wastewater treatment. J. Chem. 2018:1–13.

Herrera, V. 2019. Reconciling global aspirations and local realities: Challenges facing the Sustainable Development Goals for water and sanitation. World Dev. 118:106–117.

Jain, M., A. Majumder, P.S. Ghosal and A.K. Gupta. 2020. A review on treatment of petroleum refinery and petrochemical plant wastewater: a special emphasis on constructed wetlands. J. Environ. Manage. 272:111057.

Likitswat, F., S. Dejnirattisai, A. Sahavacharin, K.N. Irvine and L.H.C. Chua. 2023. Designing Ecological Floating Wetlands to Optimize Ecosystem Services for Urban Resilience in Tropical Climates: A Review. Futur. Cities Environ. 9.

Nuruzzaman, M., A.H.M.F. Anwar and R. Sarukkalige. 2022. Metal Removal Kinetics, Bio-Accumulation and Plant Response to Nutrient Availability in Floating Treatment Wetland for Stormwater Treatment. Water 14:1683.

Shahid, M.J., A.A. AL-surhanee, F. Kouadri, S. Ali, N. Nawaz, M. Afzal, M. Rizwan, B. Ali and M.H. Soliman. 2020. Role of microorganisms in the remediation of wastewater in floating treatment wetlands: a review. Sustainability 12:5559.

Shahid, M.J., M. Arslan, S. Ali, M. Siddique and M. Afzal. 2018. Floating wetlands: a sustainable tool for wastewater treatment. Clean–Soil, Air, Water 46:1800120.

Stefanakis, A.I. 2019. The role of constructed wetlands as green infrastructure for sustainable urban water management. Sustainability 11:6981.

Stefanakis, A.I. 2020. Constructed wetlands: description and benefits of an eco-tech water treatment system. Waste management: concepts, methodologies, tools, and applications. IGI Global. pp.503–525.

Sun, L., H. Zhao, J. Liu, B. Li, Y. Chang and D. Yao. 2021. A new green model for the bioremediation and resource utilization of livestock wastewater. Int. J. Environ. Res. Public Health 18:8634.

Vymazal, J. 2014. Constructed wetlands for treatment of industrial wastewaters: A review. Ecol. Eng. 73:724–751.

Wei, F., M.J. Shahid, G.S.H. Alnusairi, M. Afzal, A. Khan, M.A. El-Esawi, Z. Abbas, K. Wei, I.E. Zaheer and M. Rizwan. 2020. Implementation of floating treatment wetlands for textile wastewater management: A review. Sustainability 12:5801.

Zhu, T., Z. Su, W. Lai, Y. Zhang and Y. Liu. 2021. Insights into the fate and removal of antibiotics and antibiotic resistance genes using biological wastewater treatment technology. Sci. Total Environ. 776:145906.