Raymond A. Sierka

Influence of peat on Fenton oxidation

A diagnostic probe was used to estimate the activity of Fenton-derived hydroxyl radicals (.OH), reaction kinetics, and oxidation efficiency in batch suspensions comprised of silica sand, crushed goethite (alpha-FeOOH) ore, peat, and H2O2 (0.13 mM). A simple method of kinetic analysis is presented and used to estimate the rate of .OH production (POH) and scavenging term (ks), which were used to establish the influence of organic matter (Pahokee peat) in Fenton systems. POH was greater in the peat-amended systems than in the unamended control, and ks was approximately the same. Any increase in scavenging of .OH that resulted from the addition of peat was insignificant in comparison to radical scavenging by reaction with H2O2. Also, treatment efficiency, defined as the ratio of probe conversion to H2O2 consumption over the same period was greater in the peat-amended system. Results suggest that .OH production is enhanced in the presence of peat by one or more peat-dependent mechanisms. Fe concentration and availability in the peat, reduction of Fe(III) to Fe(II) by the organic matter, and reduction of organic-complexed Fe(III) to Fe(II) are discussed in the context of the Fenton mechanism.

Ozonation of aquatic organic matter and humic substances: An analysis of surrogate parameters for predicting effects on trihalomethane formation potential

Abstract Ozone represents a potential oxidant for controlling trihalomethanes (THMs) during water treatment. The results presented herein indicate that partial oxidation of THM precursors by ozone produces by‐products which are lesa reactive in forming THMs upon chlorination. It is demonstrated that surrogate parameters such as nonvolatile total organic carbon, UV absorbance, and fluorescence are capable of monitoring the performance of the ozonation process in reducing the THM formation potential of waters containing THM precursors.

An Energy Saving Process for the Reactivation of Activated Carbon Saturated with Organic Contaminants

Activated carbon is the best broad-spectrum adsorbent available for the removal of dissolved organic material in aqueous solution. Granular activated carbon (GAC) has been commonly used to adsorb molecules that cause taste and odor, mutagenicity and toxicity. Synthetic organics, natural organic matter (humic and fulvic acids) pharmaceuticals, personal care products and disinfection by-products (chloroform) are well removed from domestic and industrial wastewaters. Physical adsorption efficiency of GAC is due to extensive surface area within the adsorbent deposited in a large range of pore sizes and volumes while the adsorbent surface chemistry affects chemisorption of adsorbates. Activated carbons have finite adsorption capacity that when exceeded, the adsorbent must be reactivated before reuse.

Activated Carbon Adsorption and Chemical Regeneration in the Food Industry

Approximately 5.2 million pounds (2.36 million kg) of pesticides were used worldwide in 2008. In the United States alone, there are sales of more than 1,055 registered active ingredients found in 16,000 pesticides. There are negative environmental and human health consequences from the use of pesticides.