TRICKLING FILTERS

With apologies to colloidal matter, undesirable/excess wastewater constituents may be present in roughly either or both of two forms, namely soluble and/or particulate, a cutting point being about 0.45 µm. To a certain extent, nonsoluble fractions can or ought to be previously removed by appealing to essentially physical pretreatment means, e.g. settling, flotation, screening. This first step however, leaves us with an at times sizable amount of material in soluble form that will still have to be dealt with. Because further appeals to physical processes will be basically of no avail (or at least will behave as per diminishing returns laws), present environmental engineering practice resorts to and banks on the phenomenal power of natural/biological processes. Wastewater treatment plants essentially replicate in a somewhat controlled mode what has been going on in nature for ages: biological processes. In this way, "troublesome" soluble components are gladly gobbled up by living matter..