Assessment of tools for protection of quality of water: Uncontrollable discharges of pollutants

Highlights

• Appropriate crisis management tool is selected during sudden and accidental pollution.

• Water quality protection is accomplished under uncontrollable loading of pollution to the river.

• A new classification and novel constraints were offered to conserve water quality.

• A new tool for water quality protection is proposed and simulated for the first time called detention time.

• Dilution flow and detention time were calculated with a new numerical method called SEF.

Abstract

Selecting an appropriate crisis management plans during uncontrollable loading of pollution to water systems is crucial. In this research the quality of water resources against uncontrollable pollution is protected by use of suitable tools. Case study which was chosen in this investigation was a river-reservoir system. Analytical and numerical solutions of pollutant transport equation were considered as the simulation strategy to calculate the efficient tools to protect water quality. These practical instruments are dilution flow and a new tool called detention time which is proposed and simulated for the first time in this study. For uncontrollable pollution discharge which was approximately 130% of the river's assimilation capacity, as long as the duration of contact (T_c) was considered as a constraint, by releasing 30% of the base flow of the river from the upstream dilution reservoir, the unallowable pollution could be treated. Moreover, when the affected distance (X_c) was selected as a constraint, the required detention time that the rubber dam should detained the water to be treated was equal to 187% of the initial duration of contact.

Introduction

Contamination of surface water is one of the most controversial environmental issues. Pollution discharge is usually accidental and uncontrollable in the real world. This environmental hazard must be measured, simulated and calculated separately, so a suitable crisis management plan should be applied. Control of allowable concentration of the pollution for daily water demands needs special instruments for water treatment. Employing water refinery facilities is an inevitable resolution but establishing such equipment have notable expenses, so proposing applicable and replaceable solutions which are effective and also low in cost is crucial. Obviously a very cost-effective way to confront any disturbance is using the natural ability of a water system. This natural ability in the river is achieved by adjustment of water flow versus entered pollution World Meteorological Organization Technical Report, 2013). Assimilative capacity and dilution flow are well-known instruments to protect water quality which employ regulation of water flow for treating polluted water. Assimilative capacity and dilution flow were used to manage controllable and uncontrollable pollution entrance, respectively (Hashemi Monfared et al., 2017).

Regulation of water flow to minimize the hazards caused by sudden and unallowable entered pollution is a practical remedial action to manage pollution crisis, which is called dilution flow (Zhang et al., 2017). To determine the amount of dilution in the previous researches, a method was extended employing the equation of mass-balance for aluminum and considering sources of aluminum from surface water, groundwater and filter-backwash effluents. Hazards caused by water withdrawal, sedimentation and spill discharge from the reservoir were investigated. The method was used for 13 reservoirs and data on aluminum and dissolved organic carbon (DOC) concentrations in reservoirs and influent water were collected (Colman et al., 2016). Dilution flow was employed as a tool to protect the hypothetical case study when the pollution discharge into the river is accidental or uncontrolled (Ciolofan et al., 2018, DeSmet, 2014). Their simulation was based on the analytical method of pollution propagation (Farhadian et al., 2014, Skulovich and Ostfeld, 2017).

Precise solving of the pollution transport equations by different methods and models is the first step for accurate modeling of the behavior of pollution. It was proved that Symmetric Exponential Function (SEF) and Quick methods are appropriate to simulate the tools for water quality management with high accuracy (Hashemi Monfared and Dehghani Darmian, 2016, Ardestani et al., 2015). Pollution transport in the river was simulated using numerical methods and quality of that river water was managed (Falconer and Liu, 1988, Gao et al., 2015, Farhadian et al., 2016, Farhadian et al., 2018). Interaction between the finite-difference technique and the real GA optimizer to eliminate a heavy-metal pollutant plume from an aquifer was illustrated (Awad et al., 2011).

Compromising between desires and conflict targets in the state of abrupt pollutants discharge and selection of the appropriate strategy to analyze the reaction of water resource system is available by use of the system quality-quantity modeling and conflict-resolution methods. These methods are done employing the CE-QUAL-W2 model (Shokri et al., 2014) for loading of coliform pollution in the Karaj Dam, Iran (Haddad et al., 2013). Oscillation in quality of reservoir water was modeled and estimated upon entered biological load using CE-QUAL-W2. Some factors affected the pollutant behavior significantly, such as stored water volume in the reservoir and location of the entered contamination (Haddad et al., 2015).

Many researchers centralized their investigations on the identification of the pollution source in surface waters (Khorsandi et al., 2014). Information of the water quality and networks monitoring as necessary factors in tolerable of water resources management and pollution control were determined. Their management and evaluation approach had been used to optimize the monitoring of water quality network in the Heilongjiang River, northeast China (Chen et al., 2012). A method to optimize monitoring networks of water quality in river-reservoir systems to determine optimal sampling locations and discover the sudden pollution release [methyl tert-butyl ether (MTBE)] were developed considering two goals 1) minimizing the prediction error at the reservoir's outlet gate; and (2) minimizing the average time where MTBE is detected at sampling locations. A support vector regression (SVR) tool is coupled to non-dominated sorting genetic algorithm II (NSGAII) to optimize the sampling locations of water quality (Aboutalebi et al., 2016a). Transport of pollutants released into a water body was simulated by use of data-mining tools. Concentration of (MTBE) at various locations within a river-reservoir system was modeled by apply the (SVR) which is a data-mining tool (Aboutalebi et al., 2016b). Framework to Multi-objective optimization was proposed for determination of optimal load of pollutants into rivers considering three factors including: (1) the total cost of treatment, (2) the balance between the pollution dischargers and (3) the dissolved oxygen (DO) concentration in the water (Yandamuri et al., 2006). Complementing analytical chemistry approach to manage effluent or surface water was investigated by considering the importance of biomonitoring methods with special focus on zebrafish models (Li et al., 2018).

Data-driven models were considered to analyze indices of water quality (Mahmoudi et al., 2016, Karamouz et al., 2003, Solgi et al., 2017). Genetic programming (GP) as a data-driven model is an efficient instrument for identifying water quality parameters (Orouji et al., 2013).

Interaction between quality condition of soil and water were performed to achieve the best quality management tool according to the region's situation (Ali et al., 2017a; 2017b; 2018). A study investigated the pollution degree of toxic metals and rare earth elements in comparing sediment, soil and plant samples surrounding rivers in the African copperbelt area specified by the presence of numerous abandoned mines and industrial mining activities (Atibu et al., 2018). Evaluation of ecological hazards (Yang et al., 2017, Wang et al., 2018) and risk assessment of two coastal ecosystems in Iran including Hara Protected Area and the Azini Bay is accomplished using common pollution indices, by measuring daily concentration of Pb, Zn, Cu, Cd (Ghasemi et al., 2018) and similarly for Meiliang bay of Taihu lake in China (Rajeshkumar et al., 2018). Moreover, metal pollution indices and sediment specifications were evaluated (Sharifinia et al., 2018). Suitable strategies to evaluate the health risk and uncertainties from trace organic chemicals in water environment were reviewed (Bieber et al., 2017).

One of the most important characteristics in the field of water resource management is considering of the opinions of stakeholders and fulfilling their requirements. Optimal operation of the reservoir systems is a challenging function in management of water resource; including stakeholders with several utilities which may sometimes are conflicting to each other (Fallah-Mehdipour et al., 2014).

Assimilative capacity of the river was proposed and calculated for managing controllable pollution discharge (Hashemi Monfared et al., 2017). In order to guarantee quality and safety of water and also improve consumer satisfaction, existence of an integrated quality management system against controllable and uncontrollable pollution entrance is essential. Therefore in this investigation, the management of uncontrollable loading of pollution which is greater than river's assimilation capacity has been discussed. For achieving this purpose based on the environmental conditions of the region and stakeholders requirements, two economical utilities for water quality management have been used; dilution flow and a new tool called detention time which is introduced and simulated in this study. These quality conservation tools rely on the adjustment of river-reservoir flow to tackle various amounts of pollution hazards and enhancing the quality of the water.