Phosphate Removal by Chemical Precipitation

In wastewater treatment plant, the level of phosphate can be lowered by means of incorporating the phosphate compound into suspended solids and then eventually these solids will be removed. High level of phosphates (more than 1ppm) in the water is not a desirable condition because this will lead to problems later part on discharge whereby it will cause algae bloom. There are basically two different methods for phosphate removal involving wastewater plant technology, one is by using biological phosphorus removal technique and another is by Chemical Precipitation.

Chemicals that are often selected to help in phosphate removal are either lime or metal salts for instance like ferric chloride and aluminum sulfate, which are often used in conjunction with polymers and alum. Lime is the less preferred choice of chemical because it can lead to huge noticeable increase in the volume of sludge generated. Usually chemicals can be added at different stage of wastewater treatment process either during the start of raw wastewater feed into primary sedimentation or during biological treatment step.

The chemistry behind the whole process involving chemical precipitation is very much complex. Usually it is difficult to predict the outcome of chemical reaction because there are possible side reactions that may occur with other compounds present in the wastewater. Nowadays improved formulation of chemicals plus with polymer can significantly assist towards phosphate removal. Check with local manufacturers that will be able to provide more details on the best chemical combination to use.

Other chemical process related to wastewater treatment:
Ozone Disinfection before final discharge

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