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AGROIWATECH Informe resumido

Project ID: ICA2-CT-2002-10010
Financiado con arreglo a: FP5-INCO 2
País: Serbia

Optimal operating conditions to get the sludge with increased useful material content and increased dewaterability

Anaerobic stabilization as a form of biological treatment is used to remove organic contaminants from the industrial waste streams. Studies of the conditions of anaerobic treatment of solid wastes from agro-industry (brewery, sugar factory and edible oil refinery) and its further stabilization on the increase in content of useful materials and simultaneous increase in sludge dewaterability (as an important characteristic from the aspect of its handling and utilization), was carried out on a pilot-plant scale.

Composition of the initial mixture in the experiments involving solid waste from brewery, sugar factory and edible oil refinery was chosen on the basis of the production characteristics of these industries. Studies of the effect of treatment of agro-industry solid waste and its further stabilization by adding CaO on the quality of obtained sludge in respect of content of organic matter and nutrients (N and P), as well as its dewaterablity, encompassed eight series of experiments with different substrates (two from brewery, two from sugar factory, and one from edible oil refinery). In the frame of the study of the effect of conditions of anaerobic treatment on dewaterability of the obtained sludge, the effect of pH correction of anaerobically stabilized sludge was also examined.

The results obtained can be summarized as follows: careful choice of the initial mixture composition can to a great extent influence the quality of the final product of anaerobic digestion in respect of content of useful materials and dewaterability of the sludge. However, for brewery solid waste composition didn't affect efficiency of dewatering. Anaerobic treatment of solid waste from edible oil refinery gave a sludge of increased nutritive value, but characterized by a long filtration time and a low efficiency of dewaterability.

The comparison of the results of anaerobic treatment of different substrates in respect of content of useful materials and dewaterability shows that the highest-quality sludge in respect of nitrogen matter content was obtained by digesting solid brewery waste (C/N ratio 5.39 and 10.85), and from the aspect of dewaterability by digesting sugar factory waste. Adjustment of the pH of the investigated anaerobic sludges to pH≤3 yielded improved dewaterability.

Stabilization with CaO of the anaerobic sludge originated from brewery solid waste reduced content of nitrogen matter, important for its potential use as a fertilizer, but on the other hand increased the dewaterability of the stabilized sludge. Stabilization with CaO (6-10%) of the anaerobic sludge originated from sugar factory waste yielded a decrease in organic matter content, whereby the C/N ratio showed also a decrease. Judging from dewaterability parameters, a dose of 6% was sufficient to improve the sludge quality. Stabilization with CaO (4-10%) of the anaerobic sludge originated from edible oil refinery yielded improved sludge characteristics in respect of content of useful materials and dewaterability, whereby a dose of CaO of 4% was sufficient to produce the desired positive effect.

Reported by

University of Novi Sad
Trg Dositeja Obradovica 3
21 000 NOVI SAD
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