“Some chemicals that we use in our everyday lives including medicines (such as prescription and non-prescription drugs), personal hygiene products (for example, soaps, disinfectants, …) and their chemical additives (such as preservatives) are present in the environment and associated with various sources such as municipal wastewater treatment plants, runoff from agricultural and urban land surfaces, and septic systems. These contaminants are referred to collectively as “contaminants of emerging concern” (CEC) and represent a shift in traditional thinking as many are produced industrially yet are dispersed to the environment from domestic uses” (USGS).
Several CECs have been detected downstream of River May which is to be abstracted for the provision of drinking water for a rural community of 3000 residents. A refinery is located 20 km upstream of the point of abstraction. The refinery discharges its effluent into the river and high levels of PAHs have also been detected in the river water.
The key CECs that has been detected includes:
CEC Levels in River May
1,4-Dioxane 2 mg/l
Ethinyl Estradiol (17-alpha ethynyl estradiol) 15 ng/l
Erythromycin 80 ng/l
Perfluorooctane sulfonic acid (PFOS) 200 ng/l
Carbamazepine 430 ng/l
Bisphenol A 100 ng/l
Diclofanac 150 ng/l
PAH 300 ng/l
1. Propose a design solution for the treatment of the River May water for potable use. Justify your proposed solution (800 words).
2. Critically evaluate the occurrence and treatment of a chosen CEC in either Europe, North America or Asia (1200).
Distribution of marks:
A clear rational and justification for design solution (10%)
Appropriateness of design solution (20%)
Presentation and references (10%)
Appropriateness of evaluation of the chosen and coherence CEC (20%)
State of the art review of occurrence and treatment (30%)
References and presentation (10%)
1. You are expected to use the CUHarvard referencing format. For support and advice on how this students can contact Centre for Academic Writing (CAW).
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3. Any student requiring an extension or deferral should follow the university process as outlined here.
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6. Assignments that are more than 10% over the word limit will result in a deduction of 10% of the mark i.e. a mark of 60% will lead to a reduction of 6% to 54%. The word limit includes quotations, but excludes the bibliography, reference list and tables.
River May Water Treatment
Water treatment for drinking requires a comprehensive system. The system becomes even more elaborate when such water could contain industrial effluent. Treatment of such water requires a thorough analysis to check on levels of various contaminants and how best they can be removed to ensure the water is safe for drinking (US EPA, 2019). Normal water treatment plants remove most water contaminants. However, the contaminants of growing concern represent the category which cannot be removed through the contemporary water treatment method (Ma et al., 2012). Instead, additional effort should be made to deal with such components which may have devastating health when ingested by humans and animals. This paper seeks to justify the designed treatment plan for River may remove all waste including the contaminants of growing concern.
The first steps of water treatment are characteristic of all water treatment systems. Secondary treatment of water through coagulation and flocculation removes sediments from wastewater. Such sediments include solid particles such as soil and industrial wastes. Advanced treatment, on the other hand, comprises of various processes which assist remove other contaminants including contaminants of emerging concern from wastewater to make it safe for drinking.
According to Furlong et al. (2017), there are various treatment plans for dealing with contaminants of emerging concern. For instance, personal care and pharmaceutical products in source and drinking water can be removed through various processes. Personal care and pharmaceutical contaminants of emerging concern such as Ethinyl Estradiol (17-alpha ethynyl estradiol), Erythromycin, Carbamazepine, Bisphenol A, and Diclofenac, can be removed from water through chlorination treatment and oxidation systems. Use of granular activated carbon also removes these pharmaceutical and personal care products up to 99%% (Ma et al., 2012). Reverse osmosis, nanofiltration, and membrane filtration are also used for efficient removal of personal and pharmaceutical products from the water such as erythromycin. All pharmaceuticals at typical 3mg/L dosage can be removed by the chlorination process (Furlong et al., 2017).
Ingestion and skin contact with PAH is found to have carcinogenic effects. Extremely low contents of PAH is required to have a 10^-6 cancer risk level. Exposure to PAH also leads to systemic toxicity and tissue damage. A polycyclic aromatic hydrocarbon (PAH) is removed from the water through aeration of the water. These compounds are hydrophobic hence escape the aerobic wastewater treatment by binding with the sludge. As a result, they are eliminated from the drinking water. In case the contents are still present in drinking water after the aerobic process, anaerobic degradation is used to remove them under methanogenic conditions (Nepis, 2019).
Perfluorooctane sulfonic acid is a man-made chemical present in the environment and used to make consumer products water resistant and non-stick. In many industrial processes, it is contained in foams used for fire fighting. However, Perfluorooctane sulfonic acid persists in the environment and bioaccumulates in bodies of animals and humans (US EPA, 2019). Perfluorooctane sulfonic acid is dissolved in River May’s water which makes it extremely difficult to remove it. The content is removed through high pressure activated carbon absorption and ion exchange. Activated carbon treatment is used to adsorb synthetic organize chemicals, taste and odor compounds, and natural organic compounds in treatment systems for drinking water. Adsorption is a chemical and physical process where substances are accumulated at the solid and liquid interface. The highly porous activated carbon material with coal, lignite and wood contents is very efficient in removing the Perfluorooctane sulfonic acid contents from the water (Nepis, 2019). The carbon can be in the form of a powder or granular activated carbon.
Ion exchange treatment, on the other hand, utilizes a polymeric highly porous material which is insoluble in water, acid, and base. Hydrocarbons are used to make the tiny beads comprising the resin. Ion exchange resins can be anionic or cationic are used to remove negatively and positively charged ions of Perfluorooctane sulfonic acid (PFOS) and 1,4-Dioxane from the water by attracting them (Nepis, 2019). This technology is highly efficient because resin regeneration is not needed hence there are no contaminants requiring disposal, treatment and special handling (Ma et al., 2012).
High-pressure membranes such as reverse osmosis and nanofiltration also remove Perfluorooctane sulfonic acid (PFOS), pharmaceuticals and personal care products. High-pressure membranes are dependent on the permeability of the membrane. A nanofiltration membrane has a high rejection degree to hardness while reverse osmosis membranes have high rejection degrees to all salts. Therefore, nanofiltration removes particles while the reverse osmosis removes minerals (Furlong et al., 2017).
In conclusion, water treatment disinfectants such as UV, monochloramine, activated charcoal, free chlorine, and ozone can remove pharmaceutical and personal care contaminants of emerging concern from River May. High pressure membrane processes such as nanofiltration and reverse osmosis activated carbon, and ion exchange is used to remove Perfluorooctane sulfonic acid, 1,4-Dioxane, pharmaceuticals and personal care products from the river. Removing all contaminants of emerging concern from River May using a single process requires research and invention.
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