Recent Developments in the Application of Ultrasonication in Pre-Treatment of Municipal Sewage Sludge

Abstract

This article presents the experience in the field of using ultrasonication as a pre-treatment method of SS (sewage sludge). On the basis of a review of the literature, the effect of pretreatment of sewage sludge by US (power ultrasound) with different parameters on SS quality parameters and energy effects of the process was presented. The status of commercial applications of US as a sewage sludge pretreatment method was also presented, using the example of wastewater treatment plants in Poland. It was shown that the effective management of SS is an important technological and environmental problem in many wastewater treatment plants. Therefore, new strategies for dealing with this by-product are constantly being sought. In large wastewater treatment plants, the dominant method of stabilizing SS is AD (anaerobic digestion). However, due to the characteristics of SS, it shows low efficiency. Among the numerous strategies, US is one of the new technologies that is finding several full-scale implementations. Its application allows for solubilization of organic matter, disruption of microbial cells, as well as SS floc description and enzyme release. A number of benefits can be obtained as a result of these developments, including increased methane production, improved reaction kinetics and removal of organic matter, as well as enhanced settability and dewatering of SS, thus contributing to savings in wastewater treatment plants.

The Use of Hydrodynamic Cavitation to Improve the Anaerobic Digestion of Waste from Dairy Cattle Farming—From Laboratory Tests to Large-Scale Agricultural Biogas Plants

“…To date, many techniques have been analysed to improve the susceptibility of organic substrates to degradation under anaerobic conditions. These include comminution and mechanical destruction [24], treatment with acids and bases [25], advanced oxidation [26], enzymatic hydrolysis [27], disintegration with ultrasound [28,29], hydrothermal depolymerisation by conventional [30] and microwave heating [31], the use of low temperatures in the freezing processes [32] and the injection of solidified carbon dioxide [33,34], as well as the use of high-voltage disintegration [35]. Unfortunately, in many cases, the optimistic results of the preliminary investigations, which were achieved under laboratory conditions, were negatively confirmed in pilot studies on a technical scale [36].…”