Adsorptive separation of phosphate oxyanion from aqueous solution using an inorganic adsorbent

Phosphate removal from aqueous solution was explored using granular ferric hydroxide (GFH) as an inorganic adsorbent. Adsorption, desorption and kinetic studies were conducted on laboratory scale to evaluate the performance of GFH as an adsorbent for low concentrations of phosphate solution. The effect of pH on adsorption was investigated, and phosphate uptake was shown to decrease with an increase in solution pH, with maximum removal seen to occur at pH 3. The experimental data best fit the Temkin isotherm at both pH 3 and 4. Uptake of phosphate by GFH follows second-order kinetics, with the small particle range (76–200 μm) removing phosphate from the solution more rapidly than the larger particle range (710–850 μm). The kinetic results suggest that intra-particle diffusion is an important factor in phosphate adsorption onto GFH. Thermodynamic parameters (ΔG°, ΔH°, ΔS°) were evaluated, and the results indicated that the adsorption process was endothermic and spontaneous. This study demonstrates that GFH has potential to be used as a cost-effective adsorbent for phosphate removal from aqueous solution.     

Developing a sustainable energy strategy for a water utility. Part I: A review of the UK legislative framework

Increasing political effort to improve water quality across the UK and Europe has led to water and sewerage companies investing heavily in high-tech wastewater treatment plants capable of producing high quality effluents. Consequently, amounts of bought-in electricity used for wastewater treatment has and will continue to increase significantly over coming years, while greater provision of enhanced sewage treatment also produces greater volumes of sewage sludge requiring treatment and disposal. Over the same period, tougher controls on the quality of biosolids applied to agricultural land have also been introduced, while there has been an international attempt to reduce the use of fossil-fuel derived power sources because of concerns over global warming. The latter has brought about the introduction of financial instruments, such as the Climate Change Levy, to curb energy use, promote energy efficiency and encourage the development of renewable energy technologies. These factors are set to drive-up the costs of providing adequate sewage treatment services, while at the same time, a tough regulatory line taken to control profits on regional monopolies held by the UK water companies will significantly reduce their revenues over the period 2000-05. The result is that, financially, UK water and sewerage companies face their most challenging period since privatisation in 1989. This paper briefly outlines the current regulations relating to water quality and energy use that will affect water company operations over coming years.