Pochai, Nopparat

Preferred name

Pochai, Nopparat

Alternative Name

Pochai, N.

Main Affiliation

School of Science

nopparat.po@kmitl.ac.th

Now showing 1 - 10 of 56

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A simple mathematical model of water quality control for recirculating pond on a shrimp farm
(2021-01-01)
Kraychang, Witsarut
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Meechowna, Sompoom
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Welamas, Weerapol
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Pochai, Nopparat
— In many countries, shrimp is one of the most valuable export commodities. Shrimp farming raises a number of issues, including shrimp waste contamination, shrimp feed residues, and biochemical reactions in the shrimp pond. In this research, mathematical models were utilized to analyze the water quality in shrimp ponds and wastewater treatment ponds for circulation systems, with BOD serving as a significant indication of water quality. In the circulation system, two separate ponds were investigated: the shrimp pond and the wastewater treatment pond. The shrimp pond was tested for pollutant levels generated by shrimp excretion, shrimp feed residues, and biochemical reactions. A Chaipattana low-speed surface aerator was used to treat the shrimp pond pollutants, and some of the waste was drained to the next pond. The pollutant levels in the treatment pond were investigated. This pond is polluted by sewage from the shrimp pond as well as biological reactions. Lower-efficiency aerators treat the contaminants in the treatment pond, and part of the waste is transferred to the next pond. The advection equation is being used to describe the pollutant concentration in two ponds, and Runge-Kutta order 4 is also being used to determine the approximated solution to the problem. The results of the mathematical model are presented in graphs and tables comparing the pollutant concentrations in many cases. The last section shows an example of wastewater treatment by aerator in a shrimp pond. It was found to reduce the number of days needed for wastewater treatment. The water quality could generate shrimp in this condition, but the water quality could not grow shrimp if the aerator was not turned on the first day of shrimp farming and then turned on the next day. On the first day of shrimp farming, the aerator should not be turned off since the pollutant concentration would be high, making wastewater treatment difficult the next day. In addition, the research showed a maximum five-day reduction in wastewater treatment time (last days of the month). When wastewater is treated every other day, every three days, or every five days, the pollutant concentration must be lower than the minimum necessary for shrimp farming. It can also be used to reduce the cost of water treatment by saving energy.
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A One-dimensional Salinity Measurement Model in the Chao Phraya River with the Chao Phraya Barrage Dam Using a Shooting Method
(2023-03-01)
Vanishkorn, Buddhaporn
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Pochai, Nopparat
Sea water receding from the Gulf of Thailand causes salinity diffusion in the Chao Phraya River, Thailand, and the amount of northern water is reduced in the dry season. It has an impact on people, particularly the generation of tap water. The Samlae raw water pumping station is the major pumping station. The Ban Krachaeng subdistrict is located in Mueang district, Pathum Thani province, and is affected by saltwater intrusion, which causes the salinity level to exceed the recommended threshold. In order for the Metropolitan Waterworks Authority (MWA)'s water supply system to achieve the standard, the salinity index at the Samlae raw water pumping station is controlled to not exceed the surveillance threshold of 0.25 g/l in this research. A barrage dam consists of a number of large gates that can be opened or closed to control the amount of fresh water passing through. There is a Chao Phraya barrage dam which is across the Chao Phraya River at Chai Nat, the northern part of the focused area. The objective of this research is to demonstrate a onedimensional steady-state salinity measurement model in a river with a barrage dam. Irrigation is done in rivers with dams using the shooting method to estimate the solution. The results obtained from simulating simulated salinity measurements from Phra-Nakhon Tai Power Plant Station to Samlae Station demonstrated that the shooting method can be used to accurately estimate the solution. Freshwater flow velocity and salinity dissolving efficiency were discovered to be the most important elements controlling salinity levels. The suggested salinity control approach may help to regulate the salinity level until it reaches a normal level.
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Numerical groundwater quality assessment model using a new fourth-order scheme with Saulyev method
(2020-10-02)
Khatbanjong, Suriyun
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Pochai, Nopparat
Landfill is a cause of environmental groundwater pollutant. Landfill operations most feasible in many medium income developing countries. The groundwater pollutant measurement is required to control the drinking water quality. The mathematical model are introduced to predict the environmental impact assessment. The predicted impact of groundwater quality in is needed if a landfill project is planned to constant in considered area. In this research, a long term groundwater quality assessment in heterogenous soil model is proposed. There are two numerical models are introduced. The traditional forward time centered space finite difference technique is used to approximate the groundwater pollutant concentration in an area around a landfill. The new fourth-order finite difference technique with Saulyev method is also employed to approximate the solution as well. The approximated solutions are compared with the ideal exact solution. Both numerical techniques give good agreement approximated solution. The proposed new fourth-order scheme with Saulyev method give better approximated solution than the traditional method. The propose numerical models can be apply to predict the groundwater quality long period of time in another type of soil-physics.
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A Mathematical Model of Hazardous Smoke Emission Control Considering Primary and Secondary Pollution Concentrations
(2024-01-01)
Oyjinda, Pravitra
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Pochai, Nopparat
The major cause of air pollution concerns is industrial development, which has an influence on human health, human lifestyle, and the environment around an industrial zone. Air quality management assists in the control and improvement of air pollution in order to lower the quantity of numerous air contaminants. The purpose of this investigation is to examine various air pollution emission control and quality control mechanisms. Several atmospheric diffusion equations are used to solve numerous air pollution concentration indices that can represent how air pollutants disperse in the atmosphere. Primary and secondary pollutant concentrations are approximated by using the finite difference technique. Monitoring points are installed for checking the air pollutant concentration levels of sulfur dioxide (SO2), sulfur trioxide (SO3), and sulfuric acid (H2SO4). Suitable emission control scenarios are proposed. The approximate solutions of air pollution control simulations at each monitoring point are compared. The air quality standard is also used to compare the results of the experiments. There are suitable emission control scenarios presented. At each monitoring location, the approximate solutions of air pollution control models are compared. The proposed strategy selects a good decision-monitoring point. According to the research, an observation area should be near an industrial area. The chosen monitoring location provides the most effective overall air quality for emission control techniques around industry and residential areas. As a result, the location of collecting for each monitoring station influences the air quality of the air pollution control schedule.
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A Simulation of Shoreline Evolution with a Groin Structure Using an Alternative Machine Learning Algorithm
(2025-07-01)
Manilam, Surasak
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Pochai, Nopparat
Uneven sediment transport is a major cause of coastal erosion. Using groin structures is one method to help slow the outflow of sediment from the shoreline. Studying coastal behavior and forecasting future shoreline changes are crucial for managing and assessing the viability of remediation strategies. This research presents simulations of shoreline evolution with a single groin structure using two different methods, such as mathematical modeling and an alternative machine learning. A mathematical model is a representation of a real-world shoreline evolution phenomenon using partial differential equations. A machine learning algorithm is designed to learn patterns and relationships directly from real data. In this research, an alternative machine learning algorithm is designed to learn patterns and relationships directly from mathematical simulation data and let the machine make a decision in a situation that it has never learned before. For mathematical modeling, we introduced a one-dimensional model to predict the shoreline evolution. The initial and the boundary conditions with related parameter settings are introduced. The Saulyev finite difference method is used to obtain the approximated solution. An alternative machine learning algorithm for unexpected shoreline evolution prediction is also proposed. For alternative machine learning simulations, we identified six suitable features for the training dataset and developed an alternative K-nearest neighbor algorithm. It provides a way of predicting the evolution of the shoreline with a single groin structure. Additionally, an exact solution in an ideal scenario is used to test the precision of the simulation as well. The results show that the Saulyev technique outperforms an alternative K-nearest neighbor algorithm due to the lower root mean square error value. Both results of them are closed together. According to the research, mathematical modeling outperforms the KNN regression technique in terms of computational effectiveness during time periods of 0.5, 1, 5, 10, 15, and 20 years. Based on the modeling configuration and parameter simplicity, the KNN algorithm is still a good option for non-expert users.
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Numerical Simulations of a Two-dimensional Vertically Averaged Air Pollution Measurement in a Street Canyon
(2022-02-01)
Thongzunhor, Hasakarn
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Pochai, Nopparat
Air pollution is the release of pollutants into the atmosphere that are harmful to human health and the ecosystem as a whole. Initially, urban air pollution was considered to be a regional problem caused largely by domestic heating and industrial emissions, both of which are now well under control. The building's canyon structure and the geometry of the streets in urban areas are street canyons. Side Street connects the two sides of the street, which are made up of portions of buildings. Street canyons, which are urban streets bordered on both sides by structures, have shown high levels of pollution. Pedestrians, cyclists, vehicles, and residents will most likely be surrounded by pollution concentrations higher than current air quality limits on these walkways. The research is focused on detecting air pollution in a street canyon. There will be an introduction to a transient two-dimensional advection-diffusion equation. A two-dimensional vertically averaged air pollution measurement model is utilized to characterize the air pollution concentration along a street canyon. The model delivers the pollutant concentration in the air each and every time. The model's air pollutant concentration is approximated using a finite difference technique. An approximation approach to open and closed boundary conditions is proposed. Wind direction effects are also modelled. The suggested numerical approaches performed well in producing a high level of agreement. Simple explicit schemes have the benefit of being simple to compute. These techniques may be used to simulate air pollution measurements in a variety of street canyons.
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Numerical simulation for salinity intrusion measurement models using the MacCormack finite difference method with lagrange interpolation
(2020-08-17)
Kulmart, Khemisara
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Pochai, Nopparat
This study aims to develop numerical simulation of one-dimensional advection- diffusion equation. We propose two different methods for salinity intrusion measurement in a stream. In the first method, the forward time centered space (FTCS) is used. In the second method, the MacCormack scheme is applied. The results from these methods can be used as salinity intrusion measurement compared with the first set of exact numbers. Then, we interpolate function at left boundary by using the MacCormack scheme compared with the second set of exact numbers. The results prove that the interpolate function can actually be used. Moreover, the parameters are used and tested with technique of the MacCormack Scheme in order to simulate salinity intrusion measurement methods. After comparing results of both methods with the first set of exact numbers, we found that the MacCormack scheme is the most suitable method.
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A Numerical Model of Groundwater Quality Assessment Using a Special A-D Cubic Spline Method
(2025-01-01)
Klankaew, Pantira
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Pochai, Nopparat
Nowadays, when the industrial sector and human habitation have expanded rapidly, causing more and more various pollutants to come out, water is considered one type of pollution that is contaminated by these community and industrial sources. When this toxic water seeps through the soil, it can contaminate groundwater sources. Groundwater contamination can affect the health of humans and other living things, both directly and indirectly. In some areas, groundwater contamination can cause the population to become sick with various diseases. Long-term groundwater quality investigations near landfill sites need the use of mathematical models. A one-dimensional advection-diffusion equation (ADE) was used to analyze the groundwater's quality by describing the amount of contamination present. The objectives are mathematical simulations that can be used to assess the quality of groundwater that becomes contaminated over a long period of time. This study proposes numerical simulations for a one-dimensional mathematical model for long-term measurement of groundwater pollution around landfills. The natural cubic spline method, the Crank-Nicolson method, the upwind explicit method, and the special A-D cubic spline method are approximated in the model solution. The exact and approximate solutions are compared in each case. The proposed upwind explicit method analysis provides close to exact and properly accurate solutions. In five to ten years, the proposed numerical model can simulate several scenarios.
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Numerical simulations for reactive nitrogen compounds pollution measurements in a stream using Saulyev method
(2020-01-01)
Vongkok, Areerat
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Pochai, Nopparat
Nutrient pollution is one of most harmful environmental problems, and is caused by surplus nitrogen in water. This nitrogen concentration occurring in water can take several forms, such as organic nitrogen, ammonia, nitrite, nitrate, and dissolved nitrogen gas. Pollution levels can be measured via data collection; however, this is a rather difficult and complex process, and the results obtained widely deviate in term of measurement. A mathematical model can be used in complicated water-quality measurement. The advection-dispersion-reaction model provides a pollutant concentration field. In this research, there are five numerical models for nitrogen pollutant concentration measurement in a stream proposed: a total nitrogen dispersion model, an organic nitrogen dispersion model, an ammonia dispersion model, a nitrite dispersion model, and a nitrate dispersion model. The traditional Forward Time Central Space finite difference technique and the unconditionally explicit Saulyev technique are employed to obtain five approximated types of organic and inorganic nitrogen pollutant concentrations in each time and place. This paper proposes five forms of nitrogen pollutant measurement model for the unconditionally stable Saulyev method, so as to make it more accurate without incurring any significant loss of computational efficiency. The five approximated forms of pollutant concentrations obtained indicate that all models improve the nutrient pollution measurement process.
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One-dimensional Numerical Simulations of Oil Spill in a Coastal Bay with Delayed Removal Mechanisms
(2025-01-01)
Kasamwan, Teerat
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Pochai, Nopparat
Oil spills in marine and coastal areas can result from various activities, such as oil drilling, transportation, shipping, tank cleaning, illegal disposal of oil-contaminated or used water, and accidents like ship collisions or sinking incidents. These events result in oil slicks or tar balls that form in the sea and eventually drift towards the coast. There are many methods for addressing oil spills, such as containment, employing skimmers, chemical dispersants, bioremediation, burning, beach cleanup, environmental restoration, and monitoring and assessing long-term impacts on the shoreline. A delay in oil spill response can have severe consequences for both the environment and local economies. When oil spills occur, rapid and effective action is essential to minimize damage. Unfortunately, delays in response can exacerbate the problem and lead to more extensive environmental harm. In this research, a one-dimensional mathematical model for an oil spill in a coastal bay with delayed removal mechanisms is considered. The governing equation for an oil spill in a coastal bay with delayed removal mechanisms is introduced. The initial and boundary conditions for an oil spill in a coastal bay are also presented. A mathematical model incorporating delayed removal mechanisms is proposed. The solution of the proposed model is approximated using a finite difference method, specifically the forward time-centered space (FTCS) method. In the simulations, two scenarios are illustrated, namely, the instant removal mechanism scenarios and the delayed removal mechanism scenarios. In the instant removal mechanism scenarios, various average removal rates and basic water flow behaviors are simulated. In the delayed removal mechanism scenarios, realistic oil spill situations are considered. Therefore, the spillage rate and removal mechanism rate throughout the simulation period are analyzed. The simulation results show that the concentration of the late-coming removal mechanism leads to a poorer recovery outcome than the faster-coming removal mechanism in all scenarios. This aligns with the reality that when oil spill removal is effectively managed, the concentration of oil in the sea should decrease. The findings of this study demonstrate that, under all circumstances, delayed oil removal has more detrimental effects on seawater recovery than speedy removal. Therefore, removing oil spills quickly and effectively will significantly reduce the amount of oil in the water.

Pochai, Nopparat

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