Improving the efficiency of wastewater sludge pretreatment by high temperature hydrolysis before digestion

Summary

The results of investigating activated sludge and primary sludge thermal pretreatment with the purpose of improving the efficiency of anaerobic digestion are presented. The highest efficiency of activated sludge organics transfer into readily soluble form is ensured after thermal hydrolysis at 160°C. The solubility of primary sludge organic matter increases evenly with the temperature increase in the range of 100–200 °С. The maximum biogas output in the ultimate digestion test is increasing after activated sludge hydrolysis at 160°С, primary sludge hydrolysis – at 180–200°С. Digestion in a continuous mode after activated sludge pretreatment at 140–160 °С results in 53% gas generation increase. Any further hydrolysis temperature increase produces a negative impact on gas generation and disintegration of activated sludge ashless matter. Thermal hydrolysis of primary sludge in thermophilic mode is not efficient. Pretreated sludge dewatering performance is improved; consequently the flocculant dosage can be reduced by 0.8–1.0 kg/t DS.

Key words

energy efficiency , sludge , fermentation , biogas , dewatering performance , thermal hydrolysis

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UDC 628.336.5

Nikolaev Yu. A., Kevbrina M. V., Dorofeev A. G., Vanyushina A. Ya., Agarev Anton

High technology of methane digestion of wastewater sludge with biomass recycling

Summary

The technology of methane digestion of wastewater sludge with biomass recycling developed at Mosvodokanal MPUE is presented. The technology advantages ensure reducing the dry weight of sludge compared to the traditional digestion due to deeper decomposition of ash-free matter, and saving the sludge transportation, dewatering and utilization costs. Introduction of the technology at large-scale facilities will provide for eliminating the problem of hydraulic overloading.

Key words

sludge , biogas , activated sludge , biomass recycling , methane digestion , thickening , specific resistance to filtration

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UDC 628.35:661.63

Belov N. A., Kevbrina M. V., Aseyeva V. G., Gavrilin A. M., Gazizova N. G.

Acidification potential of the incoming wastewater and raw sludge at the Moscow wastewater treatment facilities

Summary

The consistency of biological phosphorus elimination process depends on the readily available organic matter concentration in the incoming wastewater. The concentration of this substance in the wastewater at the Moscow wastewater treatment facilities is not high. Acidification is one of the methods of enhancing readily available organic matter concentration. The production of biologically readily available organic matter (volatile fatty acids) of raw sludge and incoming wastewater at the Kouryanovo Wastewater Treatment Facilities was evaluated in an anaerobic batch-flow reactor at various temperature and time values of prefermentation process. On the basis of the experimental results the techniques of evaluating the availability of the organic compounds for phosphate accumulating bacteria (the technique of evaluating acidification potential) was developed. Acidification potential provides for the assessment of acidification process efficiency for the reduction of phosphate-phosphorus in the effluent.

Key words

acidification , acidification potential , readily available organic matter , prefermentation , phosphorus elimination

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UDC 628.169.7:628.381

KOZLOV M. N., GRACHEV V. A., Khramenkov S. V., Shchegolkova N. M., Vanyushina A. Ya., Agarev Anton

The use of soils with addition of water and wastewater sludge for industrial crop cultivation

Summary

Industrial crop cultivation for biofuel production with the use of municipal solid wastes as fertilizers is a promising technique of improving energy efficiency. Comprehensive large-scale studies of technical crop sowing (false saffron, spring rape, false flax, brittle willow) were carried out on an experimental field with soil application of water and wastewater sludge. It was shown that soil application of sludges under oil-plants provided for the significant additional yield of rape, false flax and false saffron. The yield of tree crops was higher with the application of wastewater sludge; whereas technical herbage crops (false saffron, false flax, rape) showed higher yield with water sludge application. Under unfavorable weather conditions the application of sludge enhances the drought resistance of crops. When cultivating oil-plants on soils with high pollution concentration the seeds do not absorb hazardous substances; therefore no special safety measures are required when processing the plants for biofuel production.

Key words

utilization , sludge , sludge from water treatment plant , soil , biofuel , deposition

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UDC

Shibaev S.