An oxidation ditch is "racetrack type" reactor. It has improvised activated sludge treatment accustomed for long solid retention time which to enhance higher rate of microbial removal. However, there are few applications of oxidation ditches. Is it due to any noticeable disadvantages in oxidation ditches? Please suggest your expert opinions.
The system can be noisy and can also produce odours if not operated properly. Effluent suspended solids concentrations are relatively high compared to other modifications of the activated sludge process. It Requires a larger land area than other activated sludge treatment options. This can prove costly, limiting the feasibility of oxidation ditches in urban, suburban, or other areas where land acquisition costs are relatively high.
Regards
Oxidation ditches have an additional environmental drawback. The water is moved through the ditches using rotors, and these rotors in turn use electricity. The electricity used to operate the plant causes sulphur dioxide and other contaminants to be released into the atmosphere from coal-burning electrical plants.
all surface water agitation systems produce aerosols. this is not the problem and in any case it is possible to mitigate the sprays with special barriers. The rotors actually represent a somewhat obsolete system for the supply of oxygen to the biological reactor. The efficiency is not the best. However, this activated sludge process works very well for standard civil sewage and does not require special maintenance or complicated management software. In addition to this, if properly sized, it is also able to break down phosphorus thanks to the alternation of ox and non-ox zones (see very old South African publications: Baderno Process). It depends on what one wants.
all surface water agitation systems produce aerosols. this is not the problem and in any case it is possible to mitigate the sprays with special barriers. The rotors actually represent a somewhat obsolete system for the supply of oxygen to the biological reactor. The efficiency is not the best. However, this activated sludge process works very well for standard civil sewage and does not require special maintenance or complicated management software. In addition to this, if properly sized, it is also able to break down phosphorus thanks to the alternation of ox and non-ox zones (see very old South African publications: Baderno Process). It depends on what one wants.
It helps to add more oxygen i.e. aeration of the waste water which in turn can aid in reduction of high chemical oxygen demand.
Shuraik Kader
Not sure what you mean by "improvised" activated sludge (AS) treatment?
We do not improvise but rigorously model, design and realize many advanced AS systems for municipal sewage and for a broad range of industrial wastewaters.
In the past, we achieved good results with the now obsolete oxidation ditch loop bioreactor. Its key drawbacks are the same as for the basic AS technology:
1. it is too large with long HRT (up to 4 days for strength wastewater) and SRT (up to 90 days).
2. it consumes/wastes a lot of energy for aeration especially in shallow tanks using surface aeration.
3. it does not remove recalcitrant organics (rCOD) such as micropollutants (medicins, endocriene disruptors, ...), color, ...
4. it combines BOD removal with aerobic sludge mineralisation (requiring extra aeration) which is not efficient as compared to a anaerobic sludge digestion on thickenened sludge.
5. loop reactors are difficult to monitor, control and optimize because the concentrations of dissolved oxygen, organics, nitrogen, biosludge vary a lot over the reactor path including "dead" spots.
Hope this helps.
Dear Bruno Peeters I used the term "improvised" to state the modified AS
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