Detoxification of wastewater from the wine-making process by means of chemical/electrochemical methods

The paper monitors detoxification of wastewater from the processing of grapes through various phases of chemical and electrochemical treatment. For the purpose of removing organic / inorganic pollutants from wastewater, oxidation with ozone and sedimentation with CaO were used as preliminary treatment phases as well as three electrochemical methods (electro-oxidation, electro-reduction and electro-coagulation) utilizing electrodes made of stainless steel, iron an aluminium, with a simultaneous ozonation as the primary treatment. The toxic effect of wastewater before and after each treatment phase was monitored through the values of the germination parameter after exposure of the plant Hordeum vulgare L. to the samples of untreated/treated wastewater. The wastewater was characterized by low pH value (4.02), intense odour and colouring (28400 PtCo), high values of organic pollutants (18430 mg dm(-3) COD, 1340 mg dm(-3) total phenols, 1720 mg dm(-3) BOD5) and elevated values of nutrients and heavy metals. The synergic and additive impact among organic indicators, primarily phenols and heavy metals and a low pH value, were probably responsible for an extremely high phytotoxic impact with the EC50 value of only 0.08 % and a full cessation of the germination after the seed exposure to undiluted wastewater. A preliminary treatment with lime, which removed 46% - 99.8% of heavy metals, 90.4 % of colour, 98,3 % of turbidity, 98.6 % total suspended solids, 95,4 % of phosphates, 91.5 % of sulphates and 39 % -47 % of organic indicators, resulted in 50 % toxic impact reduction. The final treatment resulted in clear effluent without odour and a barely noticeable colouring, with a removal degree of characteristic indicators from 73.8 % to 100 %, which also fully removed its toxic impact (germination = 99.2 +/- 0.2 %; germination index = 99.2 +/- 0.2 %). Based on the above stated, it can be concluded that the selected set of methods is suitable for detoxification of biologically poorly degradable effluents of a very complex and variable composition, such as wastewater from the wine-making process. The determination of the germination parameters on the plant Hordeum vulgare L. proved to be a very sensitive, simple and inexpensive test system for monitoring the toxic impact of industrial effluents and the degree of their detoxification in different treatment phases and with different methods.