METHOD FOR CLEANING CONTAMINATED WATER

摘要

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 non acidic 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 recycled to the first. By disposing the sludge from the first aeration tank, 70-80 % of the phosphate contents 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 present; d) in the course of the biological treatment, the thermal activation of the biological culture is introduced by the recycle of 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 contaminated 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 recycle water of BOD<5 and hardness <10 in a simple and cost-effective manner. The biological treatment process described constitutes indeed an intervention for optimising contaminated 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 ability in the aeration tanks is reduced due to the high temperatures of the contaminated water and where the needs for water recycle are maximal.