Degradation of VOCs by phototcatalytic oxidation reactor using TiO2 pellets

Volatile Organic Compounds (VOCs) are air pollutants that come from burning fossil fuels and industrial emissions. They have potentially adverse health effects being carcinogenic and highly persistent in the environment. The use of photocatalytic oxidation to remove VOCs has the potential to be applied in indoor air quality improvement and industrial emission control. A fixed bed photocatalytic reactor was designed and built. UV black light lamps were installed in the reactor to provide a source of UV radiation. A non-film titania media as pellets were placed on the three fixed beds within the reactor. Toluene and acetone were used as indicators of VOCs during the experiment. With a flow rate of 12.75l/min, the oxidation efficiencies were obtained at four different concentrations of acetone laden gas streams ranging from 40ppm to 250ppm. It was found that the lower the acetone concentration of the untreated inlet gas, the higher the oxidation efficiency. The oxidation efficiency was in the range of 40–70% for various concentrations of untreated gases. Two concentrations of toluene laden gas stream were also tested using the same reactor. The oxidation efficiencies were found as 50% for 120ppm toluene gas and 45% for 300ppm toluene gas. It was found that the times required for toluene to reach oxidization equilibrium have been halved than for acetone gas stream. Other parameters such as flow rate and UV intensity were also altered to see their effects on the oxidation efficiency. A full spectrum scan was carried out using a Bio-rad Infrared spectrometer. It was found that the main components of the treated gas stream from the outlet of the reactor were CO2 and water along with small amount of untreated acetone. The suspected intermediates of aliphatic hydrocarbons and CO were found in very minimal amounts or undetectable. The research experiments supported that the TiO2 pellets can work effectively in a fixed bed photocatalytic reactor and achieve significant oxidation efficiencies for degradation of toluene and acetone as indicators of VOCs.

Estimating the increasing cost of commercial buildings in Australia due to greenhouse emissions trading

The ratification of the Kyoto Protocol by most industrial nations will result in an international greenhouse emissions trading market by or before 2008. Calculating the quantity of embodied energy in commercial buildings has therefore taken on added significance because it is in the creation of energy that most greenhouse gas that causes global warming is released. For energy efficient commercial buildings in Australia, the embodied energy can typically represent between 10 and 20 years of operational energy. When greenhouse emissions trading is introduced in Australia the cost of energy will rise significantly, particularly electricity which relies primarily on burning fossil fuels for generation. This will affect not only the operating energy costs of buildings (light, power & heating/cooling) but also the cost of building materials and construction. Early estimates of the potential cost of future greenhouse emission permits in Australia vary between $IO/tonne to $180Itonne. This cost would be imposed primarily on the producers of energy and passed on by them to consumers via higher energy costs. For a typical commercial building this could lead to an increase in the total procurement cost of buildings of up to 20% due to the energy embodied during the construction or refurbishment of the building. To assist in evaluating these potential cost increases McKean & Park, Sinclair Knight Merz and Deakin University have developed a web-based Carbon Cost Calculator for commercial buildings.

Industrial wastewater minimization

Industrial pollution emitted to the environment has created a drastic damage to the environment. Natural purification processes such as dilution and dispersion are not applicable due to the enormous amounts of discharged wastes, as they exceed the assimilative capacity of the local environment. Concern about the environment by the general public has forced governments to establish effluent standards for industrial wastes and emissions. Increasing numbers of industries each year has exerted pressure on the environment compelling regulators to further tighten the standards. This has led to modification and improvement in the existing end-of-pipe treatment facilities resulting in higher investment as well as operation and maintenance cost, whereas in recent years, implementation of proactive methods of waste minimization is gaining much attention within industrial sectors. Various waste minimization techniques such as improved housekeeping, change in process technology, change in product, change in input materials, recycling of chemical and raw materials, and recovery of byproducts are discussed in detail. A number of successful examples discussed in this paper indicate that substantial benefits can be gained by implementing waste minimization programs.