Starch-based flocculants have been emerged as a promising alternative to conventional synthetic flocculants in wastewater treatment, especially for the treatment of oil sand tailings, as they are low cost, safe, biodegradable, fairly shear-stable, readily available from reproducible agricultural resources, and do not result in secondary pollution. In this paper, three types of polymer-grafted starches (St-g-Polymer) with different charge properties were synthesized and their molecular structures were controlled by atom transfer radical polymerization (ATRP). The correlations between the charge properties of starch-based flocculants, external environmental parameters, and flocculation performance were systematically investigated by conducting jar tests under various environmental conditions. It was found that the charge properties of the branch chain had a significant impact on flocculation performance. The cationic St-g-Polymer demonstrated the best performance due to the grafting of the cationic monomer to the starch backbone which improved the solubility of the copolymer and aided in the removal of small/water-soluble particles. The results obtained could assist in guiding the selection and design of suitable biodegradable flocculants when treating targeted wastewater.
A simple UV spectrophotometric procedure is proposed for the survey of an industrial sewage system. Simple, fast and reliable, this technique has been first designed for natural and waste water. It is based on the assumption that any UV spectrum of a sample can be decomposed by using a set of reference spectra. The main application is the determination of specific compounds such as nitrate or anionic surfactants (expressed as DBS) or the estimation of global parameters such as COD, TOC or TSS. Another interest can be found in process control or alarm detection. Based on the UV light absorption by all unsaturated compounds and particularly anthropogenic organic matter, the method is obviously limited by the nature of organics. So, its use for industrial application needs a good knowledge of wastewater composition -and variation- for the choice of the dedicated spectra library. This paper will present the industrial application of UV spectrophotometry including the methods for the definition of the spectra libraries. Its application in the wastewater survey of a large petrochemical site, located in the South of France, is also presented.
A series of carboxymethyl starches (CMSs), with various degrees of substitution from 0.1 to 0.79, were synthesized and selected as a model to study the feasibility of using natural polymers as flocculants for oil sand tailings treatment. The flocculation performance of modified CMS in kaolin clay suspensions and oil sand tailings was evaluated in terms of settling rate, solids content, capillary suction time, and specific resistance to filtration of the sediment phase. It was found that the synthesized CMS effectively accelerates settling of kaolin suspensions and oil sand fine tailings, thus demonstrating the feasibility of this application.
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