New proposal paper-seperately

Issues Related to the Research Proposal
Q1. Why it is important to access clean water?
Access to clean and continuous water supply is a basic necessity for everyone. Clean water reduces the chance of gastrointestinal infections that are caused by water-borne microbes. Moreover, clean water is often fortified with minerals and metals that are necessary for humans, plants and animals. Hunter, MacDonald, and Carter (2010) stated that “safe, reliable, affordable, and easily accessible water is essential to ensure good health across humans” (n. p). However, for several decades the human race has faced the scarcity and accessibility to quality potable water. Hunter et al. (2010) highlighted that almost 7.5 liters of clean water per individual per day is needed to ensure health and sustainability. On the other hand, the value jumps by 7 times per capita when the requirements of accessibility to clean water include agriculture and sewage. Hence, Hunter et al. (2010) stated that ‘to cover all the requirements of drinking, laundry, agriculture, sewage, and daily household activities, there is a requirement of around one thousand cubic meters of freshwater” (n. p.).
Q2. What kinds of pollutants are found in domestic wastewater?
The Water Policy of different countries aims to promote sustainable supply and use of potable water by reducing the discharge of contaminants into the aquatic bodies from either urban or industrial wastes. Metals such as platinum and palladium gains access to waste water from the catalytic convertors.

On the other hand, organic pollutants that are found in wastewater include polycyclic aromatic hydrocarbons (PAH) and PCBs (polychlorinated biphenyls). Such compounds gains access to wastewater through atmospheric deposition and runoffs. Metals like cadmium, zinc, and copper gains access to wastewater from feces, pharmaceuticals, and home-care products. Natural and synthetic oestrogens and detergent residues such as nonyl phenol are also witnessed in wastewater. Such compounds are not only toxic for humans but also increase the chemical oxygen demand of wastewater.
Q3. What are Chemical oxygen demand and its importance?
Chemical oxygen demand refers to the amount of oxygen that is consumed by chemical reactions or compounds in a specific solution. COD is expressed as the mass of oxygen consumed (in milligrams) per unit volume of the solution (in liters). In an activated sludge process or in aquatic bodies the soluble particulates and organic wastes consume oxygen for biodegradation. On the contrary, microorganisms present in bioreactors or wastewater also consumes oxygen for their metabolic activities. This component is referred to the BOD (biological oxygen demand) of the solution. Together, COD and BOD are referred as biochemical oxygen demand (BCOD). Increased BCOD reduce the dissolved oxygen (DO) content of effluents or water bodies. As a result, the yield of water bodies and aquatic biota decreases due to the reduced availability of oxygen. Most of these microorganisms and compounds are biodegradable, hence; appropriate treatment of wastewater is strongly mandated to ensure the viability of clean water with adequate DO.
Q4. What is an Activated Sludge Process (ASP) and what is its significance?
Activated Sludge Process (ASP) is one of the most popular methods for treating sewage and wastewaters from industrial and agricultural settings. The process depends on a two-phase unit system; biological reactor unit and settling unit. The former unit comprises of an aerated biological reactor in which the pollutants are degraded by bacteria. On the other hand, in the settling unit (SU), the activated sludge flows and settles at its bottom. The sludge is then recycled from the SU to the bioreactor. The operational feasibility of the ASP is contended to depend on different limiting factors. Most of the models assumed only one substrate, or one microorganism, or one biochemical reaction limited the feasibility of the ASP. Although microbial death is considered in such models, however; there is no provision of entry of decay products into the recycled substrate pool. However, the operational feasibility of the ASP was considered to be limited by the presence of excess sludge. The disposal of such excess sludge could increase the operational costs of wastewater treatment plants by 50% to 60%.
Q5. Many simple models ignore the depletion of oxygen and assume that temperature is constant? Why will including these effects produce an improved model?
Different studies have tried to improve the operational feasibility of ASP and bioreactors as a function residence time and stability of the microbial population. However, only a few studies have explored the importance of oxygen depletion and temperature fluctuations in assessing the efficacy of the ASP. Oxygen depletion as a function of COD would reduce the DO content of the effluent, while temperature fluctuations in the bioreactor would lead to unpredictable rate of metabolism in the biomass. Temperature is a major determinant of ASP because of its influence on the growth and activity of microbes. An increase or decrease in the temperature of bioreactors would lead to deflocculation of the microbes. The growth or reduction of microbial population could alter the rate of metabolism of activated sludge flocks. Such unpredictable rate of metabolism could lead to substrate depletion or an excess of substrates. Both these phenomenon might influence residence times and eventually, the operational feasibility of the ASP. Hence, future approaches should try to optimize and accommodate the rate of oxygen utilization and temperature fluctuations within a bioreactor to enhance the operational feasibility of ASP.
Q6. What is the research proposal?
Problem statement
Al-Jasser (2011) highlighted explored the effluent quality of six largest water-treatment plants in Riyadh, Saudi Arabia for a period of ten months. Although the effluent quality produced by these plans complied with the recent standards laid down by the Ministry of Municipal and Rural Affairs, Saudi Arabia, there were minor and major violations for effluent quality for wastewaters that are intended for restricted and unrestricted irrigation respectively (Al-Rehili & Misbahuddin, 2001, Al-Jasser, 2011). Hence, Al-Jasser (2011) voiced the need to review the recently framed standards or to upgrade the sewage treatment process in such plants. The research proposal was framed on the findings of Al-Jasser (2011) and Abdulaziz, Hussain & Al-Harbi (2010). Abdulaziz et al. (2010) explored the role of membrane bioreactors in reducing BOD and COD of treatment plants in Riyadh, however; the results were insignificant.
Aim and objectives
The aim of the present research proposal is to upgrade the water treatment process of one of the sewage treatment plants of Riyadh to enhance the quality of effluents that are intended for restricted and unrestricted agricultural irrigation. The findings of the present study might help to improve the quality of effluents from the target wastewater treatment plants as per the recent standards laid down by the Ministry of Municipal and Rural Affairs, Saudi Arabia, The broader aim of this research is to develop and analyze a mathematical model for the treatment of polluted wastewaters from the treatment plants in Riyadh. Such simulated models would help to understand the mechanisms that are required to control the operational parameters those influence the performance of the ASP.
Research Question
The proposed research would explore one primary research question “whether ASP carried out through idealized membrane reactors leads to improved effluent quality (as featured by reduced COD, low turbidity, high DO, low suspended particulates, and low residence times) of a wastewater treatment plant of Riyadh that is intended for reuse of water for both restricted and unrestricted agricultural irrigation compared to its baseline effluent quality?.
Hypothesis
The broader hypothesis for the proposed research question is as follows:
Ha= ASP carried out through idealized membrane reactors leads to improved effluent quality (as featured by reduced COD, low turbidity, high DO, low suspended particulates, and low residence times) of a wastewater treatment plant of Riyadh that is intended for reuse of water for both restricted and unrestricted agricultural irrigation compared to its baseline effluent quality (p<0.01).
References
Abdulaziz A, Hussain, G, and Al-Harbi, O (2010). Use of Membrane Bioreactor and Activated Sludge to remove COD and BOD from sewage water in Saudi Arabia, Research Journal of Environmental Sciences, 1-8
Al-Rehili,A & Misbahuddin, M (2001). Performance of Riyadh wastewater treatment plants and evaluation of effluent reuse practice Journal of Dirasat, Engineering Sciences, 28 (2),188-202
Al-Jasser, A. (2011). Saudi wastewater reuse standards for agricultural irrigation: Riyadh treatment plants effluent compliance, Journal of King Saud University – Engineering Sciences23(1), 1-8
Alharbi, A, Nelson, M, Worthy, A, and Sidhu, H. (2015). Analysis of an activated sludge model in which dead biomass is recycled into slowly biodegradable particulate substrate Asia-Pac. J. Chem. Eng. 10, pp. 580–597
Hunter PR, MacDonald AM, and Carter RC (2010) Water Supply and Health. PLoS Med 7(11), p. e1000361
Nelson M, Balakrishnan B, Sidhu H, and Chen X (2008a) A fundamental analysis of continuous flow bioreactor models and membrane reactor models to process industrial wastewaters Chemical Engineering Journal 140, 521–528
Nelson M, Kerr, T, and Chen X (2008b) A fundamental analysis of continuous flow bioreactor and membrane reactor models with death and maintenance included Asia-Pac. J. Chem. Eng. 3, pp. 70–80