Water treatment

#The present invention relates to water treatment, particularly though not exclusively, to methods of treating aqueous systems to inhibit growth of micro-organisms.

#The presence and growth of micro-organisms in aqueous systems, especially in industrial water systems, is a concern. Examples of industrial water systems where micro-organisms are a concern include cooling water systems, pulping and papermaking systems and oil and gas field water systems.

#The presence of micro-organisms in industrial water systems may result in the formation of deposits on system surfaces. These deposits or slime can give rise to various problems. In cooling water systems, slime may restrict water flow, reduce heat transfer efficiency, cause corrosion and may be aesthetically unappealing especially if algae are present due to their visible green pigmentation. Corrosion can also occur in industrial water systems in the absence of visible slime through the action of micro-organisms.

#The present invention will now be illustrated by way of example with reference to the following preferred embodiments.

#Aqueous systems were treated by adding treatment agents comprising: (a) a phosphonium compound and (b) a stabilised halogen containing composition. The phosphonium compound (a) used was TTPC. The stabilised halogen containing composition (b) was a stabilised chlorine composition which comprised sodium hypochlorite stabilised with sulfamic acid to give chlorosulfamate.

#A suspension of Desulfovibrio vulgaris plus Enterobacter aerogenes bacteria containing from 1×106 to 1×108 cells/mL was prepared in sterile pH 7 phosphate buffer containing varying levels of sodium chloride to give the desired total dissolved solids (TDS) concentration. Aliquots of this suspension were dosed with the indicated concentrations of phosphonium compound (a) and stabilised halogen containing composition (b) with the concentrations being measured as ppm by weight of the stated composition in the dosed suspension. The mixtures were allowed to stand at room temperature. At the designated contact times, each mixture was sampled to determine the total number of viable cells of both Desulfovibrio vulgaris and Enterobacter aerogenes by serial 10-fold dilution into API RP 38 media vials and anaerobic acid producing media vials, respectively. The vials were incubated at 37° C. for 72 hours. Results were recorded as cells per milliliter.