IWA Publishing in conjunction with the International Water Association’s Young Water Professionals is happy to announce the newest post spotlighting the work of Young Water Professionals and showing how the work published in IWA Publishing Journals can be useful to those beginning their careers in the water sector.

Our 10th Young Water Professional's Spotlight Blog comes from Dr. D. Gokul, who is a Research Scientist at the Water & Effluent Treatment IC and part of Larsen & Toubro Construction in India. Dr Gokul has recently been appointed as Strategic Advisor for the Young Water Professionals (YWP) Steering Committee. You can connect with Dr Gokul on LinkedIn.

Dr Gokul was granted access to our entire journal portfolio for one month in order to select papers that relate to his research interests. Thank you to Dr Gokul for participating, we wish you the best of luck for the future!

Phthalates: A greater threat to wastewater treatment

Hello Water Professionals!

I am Dr. Gokul Dayalan, Research Scientist, Office of Chief Technology Officer, Water & Effluent Treatment IC, and part of Larsen & Toubro Construction in India. I am excited to write this blog following my election as Strategic Advisor for the Young Water Professionals (YWP) Steering Committee so I can throw some light on one of the globally emerging topics in the wastewater sector.

When contemplating wastewater treatments, I always consider water in conjunction with every other environmental component in order to implement a coordinated solution. After working for over a decade on different technologies for wastewater treatment, it’s time to diversify our focus away from the conventional pollutants which are common at our treatment plants. Leachate is generated by the interaction of MSW with water that percolates through the landfill, producing highly polluted wastewater [Ren et al., 2021]. In many developing countries, leachate wastewater contains a large amount of organic matter consisting of humic substances, along with ammonia nitrogen, heavy metals, chlorinated organics, phenolic compounds and, most importantly, phthalate compounds.

Phthalate esters, known as phthalates, are plasticizers that are used to increase the quality and durability of polymers [Wang et al., 2018]. Phthalates leach and migrate from the plastic products into the environment as they are bonded to the products by physical and not chemical means, posing serious environmental threats and potential human health problems [Asaithambi et al., 2017]. Phthalates, considered priority pollutants, have broad applications worldwide - they have a high biological toxicity to humans and are considered endocrine disruptor compounds (EDC) by the US Environmental Protection Agency (USEPA), European Environmental Agency (EEA), and other environmental agencies [Xu et al., 2007]. Specifically, Diethyl Phthalate (DEP) is commonly found in leachate and groundwater due to its high solubility and wide use in many items, among them being cosmetics, plastic products, paints, and toys. The USEPA-issued national primary drinking water regulation regarding organic chemical contaminants for DEP is 0.006 mg/L, which is the maximum permissible limit.

Studies have demonstrated the removal of organic contaminants and heavy metals from landfill leachate by various technologies, including pre-treatment techniques, such as a coagulation–flocculation process, stripping, and precipitation methods, followed by discharge to the municipal wastewater treatment plant, adsorption, or oxidation. Advanced Oxidation Processes (AOPs) have been successfully implemented for the degradation of recalcitrant substances from leachate wastewater [Mohan et al., 2019] and to improve its biodegradation by increasing the ratio of biochemical to chemical oxygen demand (BOD5/COD).

Due to the high percentage of plastics in MSW composition, there is a high concentration of phthalates in the leachate [Ayanda et al., 2016]. However, the removal of phthalates by Ozone (O3) based Advanced Oxidation Process (AOP) from the complex matrix of leachate wastewater has never been explored. In an article by Miriyam et al. [Miriyam et al., 2022], an O3-based AOP—the Peroxone process (O3 & H2O2)—was tested for the removal of DEP in real leachate wastewater from an open dumpsite. The specific goal of this study was to demonstrate the impact of the O3 and H2O2 doses during degradation on DEP removal from the leachate and the formation of ozonation intermediate by-products, in addition to changes in COD, pH, and UVC during the process. After the optimization of the AOP treatment, there was a complete removal of phthalates in the wastewater to less than 0.006 mg/L, which meets the discharge standards which protect groundwater from further degradation. The water was subsequently classed as accessible for safe water.

In summary, the role of Advanced Oxidation Processes in emerging contamination treatments have been competently explored in complex wastewater systems by depending upon the correct technologies which consider influencing factors. Water professionals working in the treatment area should focus on finding and implementing techniques which focus on the emerging issues in wastewater treatment which also indirectly improve access to safe drinking water. I have tried to highlight one of the globally emerging issues which requires further specialized research in the future.

I hope you have enjoyed reading this blog and that it sparks some new ideas regarding emerging contaminants which need to be eliminated in wastewater treatment and its applications. I hope to get a chance to discuss any ideas at a conference or workshop in the future. Feel free to reach out to me and I will be happy to hear your thoughts for collaboration.

Thank you,

Dr. Gokul Dayalan

Research Scientist

Larsen and Toubro Construction

 

Bibliography

Asaithambi, P.; Sajjadi, B.; Abdul Aziz, A.R. Daud, W.M.A.B.W. (2017). Ozone (O3) and sono (US) based advanced oxidation processes for the removal of color, COD and determination of electrical energy from landfill leachate. Separation and Purification Technology. 172, 442–449. https://doi.org/10.1016/j.seppur.2016.08.041

Ayanda S. O., Olutona O.G., Olumayede G.E., Akintayo O.C., and Ximba J.B. (2016) Phenols, flame retardants and phthalates in water and wastewater – a global problem. Water Science & Technology. 74,5, 1025-1038. https://doi.org/10.2166/wst.2016.314

Miriyam B.I., Anbalagan K., and Magesh K.M. (2022). Phthalates removal from wastewater by different methods – a review. Water Science & Technology. 85,9,2581-2600. https://doi: 10.2166/wst.2022.133

Mohan S., Hadas Mamane., Dror Avisar., Igal Gozlan., Aviv Kaplan., Gokul Dayalan. (2019). Treatment of diethyl phthalate leached from plastic products in municipal solid waste by ozone-based advanced oxidation process. Journal of Materials. http://dx.doi.org/10.3390/ma12244119

Ren Q., Gao J., Imtiaz A.S., Li C., Huang H. (2021). Increasing importance of anammox process: the present status and its development trend in municipal wastewater treatment system. H2Open Journal. 4,1, 302-320. https://doi.org/10.2166/h2oj.2021.093

Wang, Z.; Shao, Y.; Gao, N.; Lu, X.; An, N. Degradation of diethyl phthalate (DEP) by UV/persulfate: An experiment and simulation study of contributions by hydroxyl and sulfate radicals. (2018). Chemosphere. 193, 602–610. https://doi.org/10.1016/j.chemosphere.2017.11.075

Xu, B.; Gao, N.Y.; Sun, X.F.; Xia, S.J.; Rui, M.; Simonnot, M.O.; Causserand, C.; Zhao, J.F. Photochemical degradation of diethyl phthalate with UV/H2O2. (2007). Journal of Hazardous Materials. 139, 132–139. https://doi.org/10.1016/j.jhazmat.2006.06.026

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