T. Viraraghavan

Adsorption op cadmium and chromium from wastewater by flyash

Abstract The removal of cadmium and chromium from wastewater by adsorption on fly ash was investigated to determine the effects of contact time, pH, and temperature. Removals of cadmium and chromium attained an equilibrium in three hours. The alkaline (pH 7 to 8) aqueous medium favoured the removal of cadmium by fly ash, while chromium removal was maximum in the pH range of 2.0 to 3.0. Batch adsorption experiments conducted at 5°C, 10°C, and 21°C showed that adsorption capacity of fly ash with respect to cadmium and chromium decreased with an increase in temperature. The data for the adsorption of cadmium by fly ash fitted well the Langmuir isotherm while the removal of chromium by fly ash followed generally the Freundlich isotherm. The maximum removals of cadmium and chromium by fly ash were 93% and 44% respectively.

Removal of copper, nickel and zinc from wastewater by adsorption using peat

Abstract The effectiveness of peat in adsorbing copper, nickel and zinc from wastewater was studied. Batch kinetic and isotherm studies were carried out to determine the effects of contact time, pH, initial concentration of the adsorbate, and temperature on adsorption. It was found that a contact time of two hours was necessary for the adsorption to reach equilibrium. The optimum pH was found to be between 4.5 and 5.0. The data for the adsorption of copper, nickel and zinc were described well by both the Langmuir and the Freundlich models. The adsorption process was found to be exothermic.

An introduction to the use of hydrogen peroxide and ultraviolet radiation: An advanced oxidation process

Hydrogen peroxide and ultraviolet light are combined in a synergistic effect to degrade organic chemicals in aqueous solutions. The generation of hydroxyl radicals is fundamental to the process as the hydroxyl radicals are largely responsible for the success of this process. Other factors affecting the effectiveness of the process are concentration of hydrogen peroxide, water quality, UV dose and spectra, scavengers, and temperature. Several models that have been used for this process are described.

Adsorption of mercury from wastewater by peat

Abstract The effectiveness of peat in adsorbing mercury from wastewater was studied Batch kinetic and isotherm studies were carried out to determine the effect of contact time, pH and temperature on the adsorption process. It was found that a contact time of five hours was necessary for the adsorption to reach equilibrium. The optimum pH was found to be between 5.0 to 5.5. The adsorption isotherm data were described well by both the Langmuir and Freundlich models.

Application of immobilized aspergillus niger, biomass in the removal of heavy metals from an industrial wastewater

Abstract In this study we report the use of dead A. niger, biomass immobilized in polymer polysulfone in the form of spherical beads to remove heavy metals from an industrial wastewater. A packed bed column containing A. niger, beads was able to remove approximately 38 % copper, 58 % lead and 16% zinc at the end of 12 hours from the industrial wastewater containing 0.08, 0.66 and 1.78 mg/L copper, lead and zinc respectively.

Respirometry in environmental engineering

Abstract This paper discusses the application of respirometric techniques in the environmental engineering filed. The development of the instrument, and its uses from early stages have been chronicled. This technique can be used in the determination of BOD, and the biodegradability of wastewaters. The measurement of the oxygen uptake of a biomass in a sample wastewater contained in a batch reactor, over a period of time, is analyzed to find the metabolization of the organic content, in terms of the chemical oxygen demand or total organic content, or BOD for biodegradability studies. The respirometric methods are relatively simple, fast, and economical. Today with the advancement of automation, and the possibility of interface with a computer, data acquisition and analysis is possible automatically, which makes it an attractive tool in environmental control practices. There are a number of other applications, fundamentally based on the respiration rate, which have been described here. In the present contex...

Drinking water at the tap: Impact of plumbing materials on water quality

Abstract Copper and galvanized steel plumbing systems in houses contribute to trace metal concentrations in drinking water. Levels of lead, zinc, copper, iron and manganese in tap water at various locations in Regina, Canada were monitored and the effect of various factors such as building height, type of building, plumbing age and type of plumbing and water chemistry on trace metal levels was examined. It was found that there was no significant effect of plumbing age or type on the extent of metal leaching in South Regina. In North Regina, plumbing type had a marked effect on the lead and iron levels in drinking water. Lead levels in some individual residences were high; these were probably local effects. It was found that corrosion of solders did not contribute significantly to metal levels. Metal leaching into standing water was found to be mostly from kitchen faucets.

Peat‐based onsite wastewater systems

Abstract The paper will present an overview of peat‐based onsite wastewater systems based on the experience in the U.S.A., Canada and Ireland. Both laboratory and field studies have shown that peat‐based systems for septic tank effluent treatment provide excellent performance in respect of BOD, SS and coliform removals. The paper will include a typical design with a schematic diagram of a peat filter for the treatment of household wastewater.

Kinetics of anaerobic filter treatment of wastewaters

Abstract In this study, anaerobic filters treating five types of wastewaters (septic tank effluent, dairy wastewater, potato processing wastewater, slaughterhouse wastewater and whey wastewater) operated at different temperatures and different hydraulic retention times, were evaluated to determine kinetic parameters. Anaerobic filters operated at higher temperatures performed better than those operated at lower temperatures. Anaerobic filters operated at lower temperatures were the most affected by changes in hydraulic retention time.

Removal of chromium from wastewater by peat filters

Abstract The effectiveness of Saskatchewan horticultural peat for removing chromium from the City of Regina wastewater was investigated by using two peat columns each of 100 mm diameter, one column with a 300 mm depth of peat and the second column with a 500 mm depth of peat. Wastewater containing approximately 0.5 mg/L of dissolved chromium was applied to the columns twice daily for a total loading of 1 litre per day. The pH of the wastewater was between 4.0 and 5.0, and the temperature was 23±1°C. The columns were operated for a period of approximately four weeks. The 300 mm and 500 mm columns were found to produce effluents containing a mean dissolved chromium concentration of 0.031 mg/L and 0.018 mg/L respectively with removal efficiencies 94.0% and 96.6% respectively. Fully developed break‐through curves could not be developed for either column within the test period.