Environmental Technology ChimH409 (2-0-1) Michel Verbanck 2012 Universite Libre de Bruxelles Bruface Dept Water Pollution Control

Course structure Part 1. Introduction (incl. generic methods) Part 2. Air pollution control engineering Part 3. Water & wastewater treatment Part 4. Solid and hazardous wastes

As highlighted previously, excess biomass production will be first minimized by appropriate operational management of the bioreactors The cost of biomass disposal amounts to about half the cost of wastewater treatment. Note: Aeration, if used, counts for almost up to half of the rest of the cost. Actually if there was no aeration, the capital cost, including the cost of land, would be very high. This is usually unaffordable in Europe and in densely populated areas. Solid wastes generated by wastewater treatment The case of biosolids disposal

sludge mass decrease through aerobic digestion

Centrifugal separators widely used for dewatering (additives such as lime and polyelectrolytes are used, notably to counteract the affinity of sludge for water); can work (almost) continuously if necessary; but investment cost also not negligible.

Filter Presses discontinuous; necessitate supervisory manpower & operator intervention

Continuous Belt Filter Presses designed to work continuously, but apparently suffer from frequent troubleshooting & work interruptions anyway (not an optimal solution). If the purpose is to operate continuously, presumably centrifuge separators would form a better choice.

Wet oxidation process the organic fraction of sewage sludge is oxidized with pure oxygen at super-critical conditions (pressure > 221 bar, T > 374 °C).

Anaerobic sludge digester.

High rate two-stage sludge digester.