Has anyone worked with polyalumium chlorohydrate in the metal hydroxide precipitation process? Of the references that I found have been very little in explaining the mechanism of this reaction or the type of Al species that occur at pH 9.5. In the industrial wastewater pretreatment for waste containing heavy metals, the waste is treated with sodium hydroxide to form metal hydroxide. Since the hydroxide precipitation is very small, adding coagulant/ polyelectrolytes forms a gel like mass to create bigger floc, and adding a polymer helps the floc to separate out of the solution so that either sinks or float. The type of wastes that I am dealing with are metalworking fluids. Some may be semi synthetic or synthetic. Part of what the coagulant does is to neutralize the electrical charges on the oil doplets within emulisfied liquid. If someone know of resources where I could find information that would be a big help. Thanks.