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Abstract

This invention refers to an original solution for the purification of contaminated water streams with the activated sludge method, involving: a) a two-stage aeration system operating at high rate and low rate conditions respectively, where the first stage operates in anoxic conditions promoting denitration, whereas the second stage operates under oxidant conditions so that nitrates are removed to an extent of 70%; b) a system for moving the biological sludge, where the sludge produced in the first aeration tank is totally rejected, and that produced in the second aeration tank is recycled to the first. By disposing of the sludge from the first aeration tank, 70-80% of the phosphate content are removed and the system is relieved of toxicity; c) a system using special ion exchanging resins enclosed in a casing, which are inflatable in water by a factor of 200-350, which have a high ion exchange capacity, and which bind the total metal ions presents; d) in the course of the biological treatment, the thermal activation of the biological culture is introduced by recycling the culture to the first aeration tank, where conditions of toxicity related biological stress develop on the culture, so that thermal activation and selectivity of species are promoted in it; e) following the above, the installation for cleaning contaminated water operates to specification with a very high and steady yield, achieving water purification to an extent of BOD reduction by 95% and with the option for the application of tertiary purification with the development of aquatic plants, leading to the production of recycled water of BOD<5 and hardness <10 in a simple and cost-effective manner. The biological treatment process described constitutes a method for optimizing water purification installations operating with the activated sludge method. It is most suitable for use with installations located in warm climate regions where the oxygen supply in the aeration tanks is reduced due to the high temperature of the contaminated water and where the need for recycling water is maximal.

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