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Innovation of tannery waste water technology

Improve depuration technology in the tanning industry,reduce
manufacturing costs/environmental impact through a drastic
reduction of used chemical products, a significant decrease
in final sludges and an improvement in their quality.

The environmental problem facing the European tanning industry has now become dominant due to the high costs which have to be expended for the control and management of pollutant effluents. This problem affects international competition because developing countries do not carry the cost of waste purification burdens. In addition, despite the high costs sustained by factories, the full quality of the effluents, as required by the regulation in force, has not yet been fully achieved. The treatment of tannery waste waters is complex and difficult due to the great amount and excessive number of chemicals used in the manufacturing process. Normally, the average discharge quantity from 1000 kg of processed hides produces about 50 cubic metres of waste waters with 250 kg of COD, 100 kg of BOD, 10 kg of sulphides, 5-6 kg of Cr (Chrome) and 150 kg of suspended solids (data from DG XI/A/3 CEE). Consequently, there is a very high production of wastes and the industrial sector has to sustain high costs for waste water treatment and sludge disposal incurring serious problems in complying with local and national environmental laws. Moreover, waste treatments are very expensive, owing to the presence of toxic compounds and the high consumption of energy (for transport, handling, biological oxidation and physical treatments). For the EU's Directive 75/442, sludges are considered as 'toxic wastes', therefore they require a special class of landfills (2C type), and as it is now very difficult to find suitable locations, this problem is growing day by day. The partners, therefore, to keep the pollutants' concentration within the required limits, aim to investigate a new technical approach, enabling the amount of chemicals and/or number of treatments to be reduced. This may be achieved according to a 'new philosophy' that could permit compliance with the required standards, with few costs and lower global environmental impact. In practice, the intention is to stop applying the traditional physicochemical treatment and introduce specific and tailored interventions requiring negligible amounts of chemical products. In order to obtain such objectives, we need to apply a direct biological treatment to waste waters, but to do this, it is necessary to carry out preliminary elimination of undesired agents such as sulphides and chrome and set up innovatory tertiary processes. Preliminary studies and laboratory research have shown the feasibility of such treatments together with a noticeable decrease in sludges (about 50%), and an increase in their quality. These preliminary results which cannot be generalised, should now be extended, closely examined through a variety of research carried out by the partners to obtain a precise picture of the deriving processes and plant devices. The process will be tested and set up using a small-scale pilot plant. In the pilot plant the process will be optimized and suitable modifications to the layout and apparatus highlighted. In accordance with the scope and objective of the EUREKA programme, this project will enable a technology to be developed which will meet a very important environmental need of the tanning industry, and SMEs will be stimulated to take advantage of the opportunities offered by this technological innovation and more become more aware of environmental technologies. The environmental research carried out in EU countries acts along two guidelines: - modification of productive processes with 'clean technologies', aiming to reduce the production of pollutants at source (LIFE: 93/I/A123/2157, 93/I/A123/2156, 93/I/A123/2150, 94/I/A123/IT/00417/TOS) - treatment of liquid and solid wastes with technologies that, reducing their quantity and increasing their quality, making recycling possible in industrial activities (CRAFT: CR-1176-91). The present proposal is perfectly integrated with the above guidelines, since it follows the same philosophy aimed at the containment of environmental impact, in the still not developed waste waters sector. In order to test the feasibility of the proposed purification strategy, several waste water treatment trials using direct biological methods were performed by the partners, but more quantified and detailed data will be necessary on the growth of bacterial mass and its optimal yield, in unsuitable conditions, versus different chemical characteristics of the polluted water to be processed. The research activity will start with studies and experimental tests on laboratory and pilot plant scale in order to set up new technologies aimed at the elimination of undesired substances such as fats, sulphides and chrome compounds from liquid wastes, allowing their recovery and recycling in the tanning process. Trials will also be performed in order to recover fats from waste waters from sheepskin tanneries. After eliminating toxic substances, it will be possible to perform tests and research for biological degradation without preliminary physicochemical treatments. Chemical, physical and biochemical analyses will be performed on the biological mass in 'blank' and in the presence of pollutant wastes, in order to spot the limiting phase. Specific tests will be performed in order to optimize the biological process to produce the minimum amount of sludges with the maximum degree of stability. Keywords: purification, waste waters, tanneries.
Acronym: 
WASTEWATERS
Project ID: 
2 238
Start date: 
01-12-1999
Project Duration: 
24months
Project costs: 
2 520 000.00€
Technological Area: 
Market Area: 

Raising the productivity and competitiveness of European businesses through technology. Boosting national economies on the international market, and strengthening the basis for sustainable prosperity and employment.