Based on the theories of acoustic agglomeration and dust wet removal, an experimental apparatus was constructed to study the combined effects of acoustic agglomeration and atomization humidification in the pretreatment process to analyze the filtration performance of filter material. According to the concentration of coal-fired fly ash chosen in the experiments, the proper amount of atomization humidification and the proper sound pressure level (SPL) were determined. Under the relative humidity (RH) of 69% and with SPL in the range of 100 dB to 135 dB, the removal efficiency of fly-ash, the compressibility of the fly-ash particle layer on the filter media, and the performance of pulse filter cleaning were studied. The results indicate that the combined effects of sound fields and atomization humidification can effectively remove PM₁₀ and PM_2.5, and change the interaction and movement of particles, which can improve the pore structure of the fly-ash particle layer and increase the porosity of the dust layer. The results also indicate that with the proper amount of atomization humidification and appropriate SPL, the joint acoustic-atomization pretreatment can delay the filter material blocking, which reduces the pulse filter cleaning frequency and extends the filter cleaning cycle. It can also reduce the residual resistance after filter cleaning and prolong the operating lifetime of the filter media. © 2017 American Association for Aerosol Research

Ultrasonic treatment is a good method of facilitating sewage sludge dewatering characteristics. It can also promote the potential of sludge electro-osmosis dewatering (EDW), which is an accepted method of deep dewatering, but the treatment method and optimizing conditions should be determined by performing experiments. In this study, we consider two treating methods: ultrasonic pre-treatment, which uses ultrasonic treatment as sludge pre-treatment before electro-osmosis dehydration, and ultrasonic coupling, which uses ultrasonic and electric fields simultaneously. Using sludge from the Tianjin Jizhuangzi sewage treatment plant, we analyze the influence of ultrasonic intensity and treatment time on sludge dewatering by performing two different methods. The results show that they effectively facilitated sludge EDW. Under the same conditions, i.e. 2 cm cake initial thickness, voltage of 60 V for 5 min, and 0.1 MPa mechanical pressure for 5.5 min, the optimum processing conditions for ultrasonic pre-treatment were found to be 0.510 W/cm² and 3.5 min, the dehydration rate reached 34.71%, and the optimum conditions for ultrasonic coupling were 0.255 W/cm² and 3.5 min, while the dehydration rate reached 40.78%. The dehydration rates for both approaches were clearly better than 17.40%, which was obtained under pure electro-osmosis dehydration. To compare the effects of ultrasonic pre-treatment and ultrasonic coupling on the electro-osmosis dehydration process, in this paper, we present the curves of dehydration rate, electric current, electro-osmosis flow, and scanning electron microscopy for dewatered sludge. Compared with the ultrasonic pre-treatment method, the effect of ultrasonic coupling on electro-osmosis dehydration was more obvious.