Saber Ahmed

Influence of parameters on the heterogeneous photocatalytic degradation of pesticides and phenolic contaminants in wastewater: A short review

In recent years, the application of heterogeneous photocatalytic water purification processes has gained wide attention due to its effectiveness in degrading and mineralizing the recalcitrant organic compounds as well as the possibility of utilizing the solar UV and visible-light spectrum. This paper aims to review and summarize the recent works on the titanium dioxide (TiO(2)) photocatalytic oxidation of pesticides and phenolic compounds, predominant in storm and wastewater effluents. The effects of various operating parameters on the photocatalytic degradation of pesticides and phenols are discussed. Results reported here suggest that the photocatalytic degradation of organic compounds depends on the type and composition of the photocatalyst and, light intensity, initial substrate concentration, amount of catalyst, pH of the reaction medium, ionic components in water, solvent types, oxidizing agents/electron acceptors, catalyst application mode, and calcination temperature in the water environment. A substantial amount of research has focused on the enhancement of TiO(2) photocatalysis by modification with metal, non-metal and ion doping. Recent developments in TiO(2) photocatalysis for the degradation of various pesticides and phenols are also highlighted in this review. It is evident from the literature survey that photocatalysis has good potential to remove a variety of organic pollutants. However, there is still a need to determine the practical utility of this technique on a commercial scale.

Impact of Operating Conditions and Recent Developments in Heterogeneous Photocatalytic Water Purification Process

The heterogeneous photocatalytic water purification process has gained significant attention due to its effectiveness in degrading and mineralizing biorecalcitrant organic compounds. This author reviews and summarizes the recently published works on the photocatalytic oxidation of various organic compounds in wastewater with particular emphasis on the impact of various parameters on the photocatalytic degradation of pesticides, dyes, and phenols in wastewater. Recent developments using modified TiO2 and ZnO photocatalytic system for the enhanced degradation of various organic compounds are also highlighted.

Performance evaluation of hybrid earth pipe cooling with horizontal piping system

Earth pipe cooling technology is a building design approach for cooling a room in a passive process without using any customary units. It can reduce energy consumption of the buildings for hot and humid subtropical zones. This chapter investigates the performance of horizontal earth pipe cooling (HEPC) in combination with a green roof system. To measure the performance, a thermal model was developed using Fluent in ANSYS 15.0. Data were collected from three air-conditioning modeled rooms installed at Central Queensland University, Rockhampton, Australia. One of the rooms was connected to a HEPC system, the second to a green roof system, and the third standard room had no cooling system. The effect of air temperature, air velocity, and relative humidity of the hybrid earth pipe cooling performance were assessed. A temperature reduction of 4.26°C is predicted for a combined HEPC and green roof system compared to the standard room, which will assist the inhabitants to achieve thermal comfort and save energy in the buildings.

Numerical Modeling of Vertical Earth Pipe Cooling System for Hot and Humid Subtropical Climate

Energy crisis is one of the major problems facing the progress of human society. There are several energy-efficient technologies that can be applied to save energy and make a sustainable environment. Passive air cooling of earth pipe cooling technology is one of them to reduce the energy consumption for hot and humid subtropical climates. The technology works with a long buried pipe with one end for intake air and the other end for providing air cooled by soil to the desired space such as residential, agricultural, or industrial buildings. It can be an attractive economical alternative to conventional cooling since there are no compressors or any customary mechanical unit. This chapter reports the performance of a vertical earth pipe cooling system for a hot and humid subtropical climatic zone in Queensland, Australia. A series of buried pipes were installed in vertical arrangement in order to increase earth pipe cooling performance. To measure the performance of the system, a numerical model was developed and simulated using the CFD software Fluent in ANSYS 15.0. Data were collected from two modeled rooms built from two shipping containers and installed at the Sustainable Precinct at Central Queensland University, Rockhampton, Australia. The impact of air temperature and velocity on room cooling performance has also been assessed. A temperature reduction of 1.82 °C was observed in the room connected to the vertical earth pipe cooling system, which will save the energy cost for thermal cooling in buildings.

Numerical Simulation of Flow in a Photocatalytic Reactor Containing Baffles

In this study a new immobilized flat plate photocatalytic reactor for wastewater treatment has been investigated using computational fluid dynamics (CFD). The reactor consists of a reactor inlet, a reactive section where the catalyst is coated, and outlet parts. For simulation, the reactive section of the reactor was modelled with an array of baffles. In order to optimize the fluid mixing and reactor design, this study attempts to investigate the influence of baffles with differing heights on the flow field of the flat plate reactor. The results obtained from the simulation of a baffled flat plate reactor hydrodynamics for differing baffle heights for certain positions are presented. Under the conditions simulated, the qualitative flow features, such as the distribution of local stream lines, velocity contours, and high shear region, boundary layers separation, vortex formation, and the underlying mechanism are examined. At low and high Re numbers, the influence of baffle heights on the distribution of species mass fraction of a model pollutant are also highlighted. The simulation of qualitative and quantitative properties of fluid dynamics in a baffled reactor provides valuable insight to fully understand the effect of baffles and their role on the flow pattern, behaviour, and features of wastewater treatment using a photocatalytic reactor.

A Study on Energy and Environmental Management Techniques Used in Petroleum Process Industries

Petroleum process industries are one of the most energy- and emission-intensive sectors throughout the world. There are natural gas processing plant, crude oil and condensate fractionation plant, liquefied natural gas plant, liquefied petroleum gas plant, etc. that create environmental pollution by processing and handling of petroleum products. The study critically reviewed and discussed the energy and environmental management including pollution control of petroleum process industries of Bangladesh. They produce both gaseous (process gas, waste gas, etc.) and liquid (produced water, waste oil, grease, etc.) pollutants. The study found that the liquid pollutant like waste water is more hazardous and its treatment process is highly complicated due to its higher salinity, more corrosivity and grease-containing characteristics. As part of energy management, the rational use of energy and energy flow diagram of the petroleum industry is presented. Finally, a time frame measure which can be implemented in order to save energy is outlined. The study concluded that the rational use of energy and proper environmental management are essential for achieving energy and environmental sustainability of process industries.

FLOW FIELD INVESTIGATION IN A WATER TREATMENT REACTOR USING COMPUTATIONAL FLUID DYNAMICS

The hydrodynamic behaviour of a novel flat plate photocatalytic reactor for water treatment is investigated using CFD code FLUENT. The reactor consists of a reactive section that features negligible pressure drop and uniform illumination of the photocatalyst surface to ensure improved photocatalytic efficiency. The numerical simulations allowed the identification of several design issues in the original reactor, which include extensive boundary layer separation near the photocatalyst support and regions of flow recirculation that render a significant portion of the reactive area. The simulations reveal that this issue could be addressed by selecting the appropriate inlet positions and configurations. This modification can cause minimal pressure drop across the reactive zone and achieves significant uniformization of the tested pollutant on the photocatalyst surface. The influence of roughness elements types has also been studied with a view to identify their role on the distribution of pollutant concentration on the photocatalyst surface. The results presented here indicate that the flow and pollutant concentration field strongly depend on the geometric parameters and flow conditions of the reactor.Copyright