The technology of wastewater sludge vitrification in comparison with other processing methodsThe technology of wastewater sludge vitrification in comparison with other processing methods

Summary

The experts of Ekopromtekh R & D Centre, LLC have developed an innovative technology for vitrification of wastewater sludge that provides for reducing significantly the volume of wastes and obtaining a safe vitrified material to be used in construction. A comparison of the vitrification technology with other methods of sludge processing is given: depositing, sludge digestion in digesters, drying, pyrolysis, catalytic and classical incineration. In Russia, more than 90% of the generated sludge is landfilled. If this trend persists, an increase in the sludge hauling distance is inevitable. Using unprocessed sludge as fertilizer increases the risk of soil contamination. Financial models of projects that envisage using digesters and selling biogas or electricity do not pay off. In case of using the drying method to obtain fuel from sludge, almost the same amount of thermal energy is consumed as the final product contains. Therefore, the cost of dried sludge as a fuel will not be less than the cost of natural gas, and taking into account other operating costs, including delivery to the consumer, will exceed the cost of gas by 2–3 times. Pyrolysis to obtain marketable products is under development and involves a lot of research. The technology of catalytic incineration of sludge without preliminary drying does not solve the main problems of any incineration process and causes certain difficulties: the risk of emission of superecotoxicants remains; the ash must be disposed of, the autothermal regime is difficult to maintain, the catalyst wears out and requires replacement. The vitrification technology has a number of advantages, it is ready for scaling and industrial implementation.

Key words

wastewater , methane tanks , incineration , sludge , pyrolysis , sludge drying , sludge cake , vitrification , thermal methods , vitrified material , zero landfilling

Sustainable biosolids management: a review of best available technologies for sludge stabilisation and volume reduction

Summary

Australian water utilities face a significant challenge in moving towards more sustainable biosolids management. There is increasing pressure to move away from the traditional approach of land application of dewatered biosolids due to escalating transport costs, community impacts such as odour and truck movements, and the risk of changing regulation or public perception affecting the future viability of land application. Different sludge treatments have been compared regarding performances, opex and carbon foot print for 2 case studies: Australian Inland and Coastal WWTP. Results have shown that thermal sludge treatments, especially Wet Air Oxidation which is now a proven technology, are highly competitive compared to conventional sludge treatments particularly when sludge disposal costs are high.

Key words

treatment facilities , sludge , thermal drying , incineration , liquid-phase oxidation , technosand , carbon emission