Wastewater Treatment Models Research Articles

Mathematical Analysis of Oxygen Uptake Rate in Continuous Process under Caputo Derivative

In this paper, the wastewater treatment model is investigated by means of one of the most robust fractional derivatives, namely, the Caputo fractional derivative. The growth rate is assumed to obey the Contois model, which is often used to model the growth of biomass in wastewaters. The characteristics of the model under consideration are derived and evaluated, such as equilibrium, stability analysis, and steady-state solutions. Further, important characteristics of the fractional wastewater model allow us to understand the dynamics of the model in detail. To this end, we discuss several important analyses of the fractional variant of the model under consideration. To observe the efficiency of the non-local fractional differential operator of Caputo over its counter-classical version, we perform numerical simulations.

Statistical modeling and optimization of tannery wastewater treatment in a fluidized bed bioreactor with low density biomass support

Treatment of tannery industry effluent is a serious challenge due to the presence of toxic pollutants including dyes and heavy metals. This work is focused on the optimization of bed height and air flow rate for tannery industry wastewater treatment in a fluidized bed reactor with low density biomass support. Response surface methodology was adopted for the optimization of process parameters viz air flow rate, bed height and wastewater dilution ratio and the best operating conditions were identified. The optimum values for the maximum chemical oxygen demand (COD) removal are: air flow rate—233 LPH, Bed height—82 cm and wastewater dilution ratio—1:2. The results from the IFBR showed that a maximum of 90.2% of COD reduction obtained at an airflow rate of 233 LPH and initial bed height of 82 cm. In this research, a maximum colour removal of 83.4% was achieved. A high correlation coefficient (R2) value of more than 0.94 for all the three models indicates that the RSM based models predict the data well. The relative effect of variables on COD removal, colour removal and air hold up were depicted in perturbation plots.

On the Use of Mathematical Models for Wastewater Treatment: A Review and Analysis of Activated Sludge Models ASM1 and ASM3

Mathematical models describing the dynamics of key biochemical processes in conventional activated sludge processes are commonly used to design and operate wastewater treatment plants. Since the introduction of the first activated sludge model, namely Activated Sludge Model No. 1 (ASM1), in 1987 by the International Water Association, ASM models received considerable attention and several extensions were suggested. In this study, we briefly review the literature on two important activated sludge models, ASM1 and ASM3. Our literature review indicates that despite the presence of many articles on ASM there is no study on the parameter sensitivity of these differential equation models. In the second part of the study, these two models are simulated in MATLAB with different initial values and parameter combinations to develop further insight into the model structures. In the third part of the study, experiments with ASM1 and ASM3 models are conducted in MATLAB and a basic sensitivity analysis is applied for the parameters of the two models.

ABACO: A New Model of Microalgae-Bacteria Consortia for Biological Treatment of Wastewaters

Microalgae-bacteria consortia have been proposed as alternatives to conventional biological processes to treat different types of wastewaters, including animal slurry. In this work, a microalgae-bacteria consortia (ABACO) model for wastewater treatment is proposed, it being calibrated and validated using pig slurry. The model includes the most relevant features of microalgae, such as light dependence, endogenous respiration, and growth and nutrient consumption as a function of nutrient availability (especially inorganic carbon), in addition to the already reported features of heterotrophic and nitrifying bacteria. The interrelation between the different populations is also included in the model, in addition to the simultaneous release and consumption of the most relevant compounds, such as oxygen and carbon dioxide. The implementation of the model has been performed in MATLAB software; the calibration of model parameters was carried out using genetic algorithms. The ABACO model allows one to simulate the dynamics of different components in the system, and the relative proportions of microalgae, heterotrophic bacteria, and nitrifying bacteria. The percentage of each microbial population obtained with the model was confirmed by respirometric techniques. The proposed model is a powerful tool for the development of microalgae-related wastewater treatment processes, both to maximize the production of microalgal biomass and to optimize the wastewater treatment capacity.

Modeling and optimization of wastewater treatment, from the Ain Chock Faculty in Morocco, using the vertical flow filter filled with pozzolana

Modeling and optimization of wastewater treatment, from the Ain Chock Faculty in Morocco, using the vertical flow filter filled with pozzolana

Study of kinetic models of olive oil mill wastewater treatment using electrocoagulation process

Study of kinetic models of olive oil mill wastewater treatment using electrocoagulation process

Modelling COD Removal from Slaughterhouse Wastewater by Electrocoagulation Using Response Surface Methodology

Modeling is an indispensable tool for a better wastewater treatment strategy. However, the modelling of slaughterhouse wastewater treatment by electrocoagulation can be difficult to achieve because of the various physico-chemical mechanisms involved. It is in this context that the objective of this study was to model and optimize COD removal and electrical energy consumption by response surface methodology (RSM) during the treatment of slaughterhouse wastewater by electrocoagulation (EC). For this purpose, a full factorial design (FD) was first used to observe the effect of experimental parameters (stirring speed, pH, time and current intensity) on COD removal and energy consumption. Then, a central composite design (CCD) was performed to optimize COD removal and electrical energy consumption. The optimum conditions are obtained at the stirring speed of 871 rpm, pH = 6.83; time of 80 min and current intensity of 1.85 A. By applying these optimal conditions for the treatment, reductions of 84 ± 1.08% of COD; 93.86 ± 0.91% of BOD; 97.80 ± 0.86% of turbidity and 99.62 ± 0.12% of PO₄^3- and an energy consumption of 9 KWh.m^-3 were obtained. Thus, this study reveals that RSM is an effective tool for the modeling and optimization of electrocoagulation.

Life Cycle Assessment of Artificial Wetland Systems for Rural Wastewater Treatment

Decentralized wastewater treatment technology, especially natural ecological treatment technology has widely been used in rural regions. In this paper, a comprehensive life cycle assessment (LCA) of a typical wastewater ecological treatment technology - artificial wetland technology was conducted. SimaPro software was applied to simulate the wastewater treatment facility, and the CML2 baseline2000 impact evaluation method was selected to analyze the environmental loads and benefits during the life cycle. The environmental impact of the facility adopting grey-black separation mode is compared with that of the unified collection and treatment model to provide scientific basis and suggestions for the selection of wastewater collection and treatment model. The results indicated that the main environmental impact of the Southeast University artificial wetland system comes from the construction and operation of the artificial wetland and aeration tank. Marine water ecotoxicity is the main impact factor, followed by freshwater water ecotoxicity.

Modeling of photosynthesis and respiration rate for microalgae–bacteria consortia

In this article, the influence of culture conditions (irradiance, temperature, pH, and dissolved oxygen) on the photosynthesis and the respiration rates of microalgae-bacteria consortia in wastewater treatment was analyzed. Specifically, some short photo-respirometric experiments, simulating outdoor raceway reactors, were performed to evaluate the response of microalgae, heterotrophic bacteria, and nitrifying bacteria to variations in environmental parameters. Results demonstrate that irradiance is the most dominant variable to determine microalgae photosynthesis rates. However, reduction in microalgae activity was not observed at higher irradiance, ruling out the existence of photoinhibition phenomena. Related to heterotrophic and nitrifying bacteria, their activities were strongly affected by the influence of temperature and pH. Moreover, the effect of dissolved oxygen concentrations on microalgae, and bacteria activities was studied, displaying a reduced photosynthetic rate at dissolved oxygen concentrations above 20 mg/L. Data have been used to develop an integrated model for each population (microalgae, heterotrophic bacteria, and nitrifying bacteria) based on considering the simultaneous influence of irradiance, temperature, pH, and dissolved oxygen. The models fit the experimental results in the range of culture conditions tested, and they were validated using data obtained by the simultaneous modifications of the variables. These individual models serve as a basis for developing a global biologic microalgae-bacteria model for wastewater treatment to improve the optimal design and management of microalgae-based processes, especially outdoors, where the cultures are subject to variable daily culture conditions.

Identification of development potentials and routes of wastewater treatment and reuse for Asian countries by key influential factors and prediction models

In recent years, the conflict between water supply and demand has increased. Using reclaimed water is an effective way to alleviate water resource shortages, prevent pollution of the water environment, and promote the sustainable development of the economy and society. Some countries and regions in Asia have implemented effective reclaimed water use practices. However, on the whole, wastewater treatment and reclaimed water use are not well developed in most Asian countries and regions. This paper identified GDP per capita and water stress as the key factors affecting wastewater treatment and reclaimed water use in Asia. Based on these factors, a development potential estimation model for wastewater treatment and reuse was established using logistic regression analyses. According to the current development status and future development potential of wastewater treatment and reclaimed water use, 48 selected Asian countries are classified into four categories using the model: high potential and high development, high potential and low development, low potential and high development, and low potential and low development. Based on the characteristics of the four classifications, development routes and measures for wastewater treatment and reclaimed water use were proposed. This study provides important information for the development planning of wastewater treatment and reclaimed water use in Asian countries, and can help in systematically promoting and improving the level of sustainable water management.

An intensified ozonation system in a tank reactor with foam block stirrer: Synthetic textile wastewater treatment and mass transfer modeling

A novel multiphase tank reactor with foam block stirrer, also called rotating foam stirrer reactor (RFSR), was used to intensify ozone mass transfer and oxidation of synthetic textile wastewater processes for the first time. Results show that the RSFR can improve the ozone mass transfer process by adjusting operation conditions and gas hydromechanics. In order to predict the volumetric mass transfer coefficient, a set of correlation was developed within ±15% deviation. Further, based on an Acid Red B (ARB) solution used as simulated synthetic textile wastewater, it was found that the removal efficiency was improved by intensifying ozone mass transfer process, and changing operation conditions can promote the transformation of the ozone oxidation path to an indirect reaction way. Finally, results show that the Fe-Co oxides coated on the foam block stirrer can further intensify the degradation processes in the ARB solution. This study gives a fundamental understanding of the intensification mechanism of the RFSR and shows the promising prospect of an RFSR used in in the wastewater treatment.

Application of stress induces ascorbate peroxidases of S. polyrhiza for green-synthesis Cu nanoparticles

The objective of this study was to assess the effects of stress on physiology/biochemical component of S. polyrhiza and its impact on CuNPs synthesis and bioethanol production. NaCl with RV5 provokes oxidative stress in S. polyrhiza and significantly increase MAD, Proline, H2O2, ROS, SOD and APX activity compare to control condition. Starch accumulation in S. polyrhiza was found 354% higher and correspond 4.4 times higher ethanol yield under stress condition compare to control. CuNPs were synthesized with an average size of 23–26 nm by purified fraction of APX having 37 KDa MW, 1.44 IU specific activity. Synthesized CuNPs were stable up to 15 consecutive cycles and potency against wide range of reactive dyes. The maximum remedial efficiency of synthesized CuNPs for COD and BOD was 55263.3 ± 3298.5 mg/m3min. and 30560.3 ± 1987.5 mg/m3min. respectively for RV5 wastewater. 0.072 mg/g of bioethanol was produced from the wet pulp remaining after nanoparticles synthesis. High efficiency of CuNPs and significant production of Ethanol, indicate that the feasibility for circular model for continuous industrial wastewater treatment.

Integrated Fuzzy AHP-TOPSIS for selecting the best color removal process using carbon-based adsorbent materials: multi-criteria decision making vs. systematic review approaches and modeling of textile wastewater treatment in real conditions

ABSTRACT Here, Fuzzy AHP-TOPSIS methodology proposed for selecting the best colour treatment process using carbon-based adsorbent materials. Cost, safety, accessibility, reuse and adsorption capacity were identified as the main criteria for decision making. The priority of the criteria based on the experts’ opinions ordered as accessibility, reuse, adsorption capacity, environment safety, human safety, material cost, equipment cost with BNP = 0.250, 0.217, 0.172, 0.144, 0.105, 0.070 and 0.049, respectively. The consistency ratio was found 0.7% (less than 10%), which was acceptable to prioritise the criteria results. Fuzzy TOPSIS decision matrix with respect to criteria for evaluating the performance of eight carbon-based adsorbent materials in colour removal was formed and adsorbents ranked according to the NCCi as powder activated carbon>granular activated carbon >carbon nano tube >graphene oxide > graphene >reduced graphene oxide >graphite>coal. Finally, the effect of key factors in the treatment of real textile wastewater using PAC was investigated and optimised with RSM-CCF modelling. The optimal value of the parameters for the best productivity (81.60%) were as follows: pH: 3, PAC dose: 9.99 g L−1 and contact time: 83.19 min, respectively. The adsorption equilibrium and kinetic data were fitted with the Langmuir monolayer isotherm model (qmax: 127.431 ADMI/g, R2: 0.999) and Pseudo-first-order kinetics (R2: 0.998). Thermodynamic parameters, i.e. R2 > 0.995, ΔH°> 0, ΔS°> 0 and ΔG°< 0 also indicated colour adsorption are feasible, spontaneous and endothermic in nature.

Optimization of recovery and utilization pathway of chemical energy from wastewater pollutants by a net-zero energy wastewater treatment model

Recovering chemical energy from wastewater is an important route to reduce the electricity input in wastewater treatment plants (WWTPs), which can significantly decrease the carbon footprint of wastewater treatment. Existing evaluation models of energy self-sufficiency focused on macroscopic substance-energy flow and considered the overall energy balance of WWTPs but ignored the substance and energy conversion process via microbial metabolism. In this study, a net-zero energy (NZE) model was established based on microbial metabolism and energy balance to estimate the potential for chemical-energy recovery from wastewater pollutants and the optimization of metabolic substrate allocation, which was implemented in a large WWTP with anaerobic digestion. The results indicate that temperature and ΔCOD were key influence factors for specific energy consumption μ. The average energy self-sufficiency rate was 43.9% under the existing operations in the WWTP. The energy self-sufficiency rates with optimized substrate allocation ranged from 58.3% to 110.6%, with an average value of 78.8%. The energy self-sufficiency rates obtained in July and August were higher than 100%, indicating that the WWTP could achieve NZE status and output electric energy in July and August, but not in other months. Seasonal variation significantly affected the potential of chemical energy recovery from wastewater pollutants in the WWTP. The average reduction in greenhouse gas emissions with energy recovery under optimal operation conditions reached 76.4% in the WWTP studied herein. The enhanced anaerobic digestion efficiency and optimization of substrate allocation between catabolism and anabolism could increase the possibility of achieving NZE status based on the model.

Simultaneous heavy metals removal via in situ construction of multivariate metal-organic gels in actual wastewater and the reutilization for Sb(V) capture

Metal-organic gels (MOGs) as outstanding heavy metals adsorbents suffer the problems of ex situ construction and not being able to reutilize, which restricts the widespread applications. To deal with this challenge, an in situ ultrasound-assisted technology integrated adsorbent fabrication with heavy metals removal in actual wastewater was firstly proposed. Characterizations analyses showed that the multivariate MOGs (MMOGs) was successfully constructed in industrial wastewater and simultaneous obtained a superb removal efficiency of 97.2%, 95.3% and 98.1% for Cu(II), Cd(II) and Cr(III), and the treated wastewater can reach the effluent standard. X-ray photoelectron spectroscopy (XPS) analysis and density functional theory (DFT) calculation indicate that MMOGs obtained the most stable structure owing to the most stable binding energy, mainly attributed to the interaction between Cu(II) and − COOH of gelators that generates additional bonding sites for capturing Cd(II) and Cr(III) during the synthesis of adsorbent. Furthermore, we successfully show the possibility to reuse the adsorbed MMOGs in the oxyanions contaminated water, and it exhibits satisfactory removal capacity for Sb(V) with favorable biodegradability. This study provides a new insight and promising model for actual heavy metal wastewater treatment as well as resource utilization.

Advanced Wastewater Treatment and Mathematical Modeling

Advanced Wastewater Treatment and Mathematical Modeling

Minimum-Time Optimal Control for a Model of Biological Wastewater Treatment

We consider a mathematical model that describes biological treatment of wastewater. The model is a controlled nonlinear three-dimensional system of differential equations. A minimum-time optimal control problem is posed that achieves the required contaminant concentration in the shortest possible time. The problem is investigated by Pontryagin’s maximum principle. The optimal control in this problem is represented by a switching function and its properties are analyzed. The results of this analysis make it possible to reduce the solution of the problem to a successive application of finite-dimensional constrained minimization and the parameter continuation method. The application of these approaches is discussed in detail, and the relevant numerical results are reported.

Plant-wide modelling in wastewater treatment: showcasing experiences using the Biological Nutrient Removal Model.

Plant-wide modelling can be considered an appropriate approach to represent the current complexity in water resource recovery facilities, reproducing all known phenomena in the different process units. Nonetheless, novel processes and new treatment schemes are still being developed and need to be fully incorporated in these models. This work presents a short chronological overview of some of the most relevant plant-wide models for wastewater treatment, as well as the authors' experience in plant-wide modelling using the general model BNRM (Biological Nutrient Removal Model), illustrating the key role of general models (also known as supermodels) in the field of wastewater treatment, both for engineering and research.

A new optimization model for wastewater treatment planning with a temporal component

The management of wastewater systems constitutes a complex problem in the environmental engineering field. The variability and uncertainty of the inflows of wastewater treatment plants involve a real risk of reducing the effectiveness of the treatments and worsen the ecological state of river basins. An adequate reduction of contaminants requires an optimal combination of wastewater contributions that must constitute the treatment inflow. The problem is complex because of different dynamics and casuistics of wastewater generation, especially when the waste is from industrial activities. In addition, a realistic focus requires consideration of the temporal component due to the distances from the treatment. This paper presents a new optimization model for planning the wastewater inflow in a consistent way, with the novelty from the inclusion of this temporal component. Under the assumption of a complete knowledge of the future, the problem can be expressed as a quadratically constrained program (QCP). With growing problem size, solvers such as CONOPT have increasing difficulties to find good solutions to such problems. Therefore, we propose solving this problem as an online optimization problem in which the quadratic terms are eliminated. Our approach was applied to a virtual case study based on a high number (200) of industrial wastewater generators (located in 4 different zones) and a single wastewater treatment plant. The results obtained evidence the applicability of the model to plan favourably the operation of treatments and contribute to sustainability in the context of the internet of things.

Development of Cost effective Waste Water Treatment Model for Sustainable Utilization of House Hold Waste Water

Development of Cost effective Waste Water Treatment Model for Sustainable Utilization of House Hold Waste Water