Fixed biomass treatment plant

This wastewater treatment plant of a medium-size urban area (about 200,000 inhabitants) is located at Nimes, in the South of France. It includes two biological processes with fixed biomass, with a clarifier in between. The first step is a trickling filter using plastic material, and the second one is a biological filtration on immersed bed (with pouzzolane). 

Several instantaneous samples have been taken along the treatment, at the inlet, after pretreatment (screening), after the first biological step, after the clarifier and after the biofilter corresponding to the outlet of the plant. 

The acquisition of UV spectra has been quickly made, and the results are presented in Fig. 24. The raw wastewater has a regular shape, and the other spectra give some 

More precisely, the spectrum evolution shows that the effect of screening on waste-water is equivalent to a primary settling. Coarse particles, the size of which is above 100 xm, are removed, and the resulting UV spectrum presents a diffuse shape due to the presence of supracolloids and colloids not removed by physical treatment. 

An important part of organic matter is removed in the trickling filter, and a slight nitrate formation can be deduced from a decrease of absorbance after 240 nm and a small 

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The first example (Fig. 10) shows the evolution of UV spectra of raw and treated wastewater for one refinery and one petrochemical site, with two different biological treatment plants, one with fixed biomass, and the other with activated sludge. For both cases, the treatment efficiency is good, with a TOC removal of around 90% (either measured or UV-estimated) and the presence of nitrate in the treated effluent. 

Communities have selected MBRs as an alternative to conventional wastewater treatment plants, in which either suspended or fixed film biological systems convert soluble nitrogenous, carbonaceous and phosphorous nutrients into settleable biomass that is removed by gravity separation. In contrast, MBRs use a microporous membrane in lieu of a clarifier to separate biomass from the treated effluent (Fig. 15.1) (Leslie, 2001). Thus, as... 

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