Particle interactions and removal of trace contaminants from water and wastewaters

The adsorption of trace contaminants on natural particles is of great interest as this adsorption enhances the possibility of removing these with low pressure filtration such as MF and UF. This study shows that natural hormones such as estrone and estradiol will adsorb to natural particles both organic and inorganic. Experiments have shown that the adsorption capacity of organics is a factor of 10 higher than for inorganics. Ultrafiltration of a solution containing NOM and estrone also indicated this adsorption as the retention of estrone showed strong relationship to the concentration of organic material in the permeate. For practical application of this finding it was investigated if it applied to activated sludge. It was found that activated sludge does adsorb the natural hormones and that activated sludge during ultrafiltration develops a dynamic membrane which enhances the retention of the hormones.

The results indicate that particle —contaminate interactions are critical for trace contaminant removal in water and wastewater treatment. Particles like activated sludge not only act like adsorbents but also like a dynamic membrane or a self rejecting layer. The authors would like to thank Ingenioer Jens Jespersens Fond and IDA’s Laane- og Hjaelpefond for providing grants to Maibritt Mastrup and Table 1 Interactions of estrone with Category I particulates (pH 7–8, 100 ng/L estrone, 1 mM NaHCO3, 24 h of adsorption) Particle Average particle diameter, Concentration, µm g/L Hematite Kaolin Bentonite Cellulose NOM/HS Activated sludge 0.075 — — *dry weight 6.3×10–3 0.1 0.1 0.1 10×10–3 5.4 Estrone adsorption, % Estrone adsorption, ng/g* 0.74 8.87 13.53 8.35 17.50 22.38 150.64 140.46 175.84 113.96 6.15 Rikke Lund Jensen. Also a big thank to Reinholdt W. Jorck og Hustrus Fond for providing a grant to Maibritt Mastrup and Otto Moensteds Fond for providing a grant to Rikke Lund Jensen. The Queensland Government and the Australian Research Council are thanked for project funding.