Study on regeneration effect and mechanism of high-frequency ultrasound on biological activated carbon

Abstract

High frequency ultrasonic radiation technology was developed as a novel and efficient means of regenerating spent biological activated carbon (BAC) used in drinking water treatment plants (DWTPs). The results of this study indicated that high frequency ultrasonic treatment could recover the spent BAC, to some extent, with the following optimal conditions: a frequency of 400 kHz, sonication power of 60 W, water temperature of 30 °C, and sonication time of 6 min. Under the above conditions, the iodine value increased from 300 mg/g to 409 mg/g, the volume of total pores and micropores increased from 0.2600 cm/g and 0.1779 cm/g to 0.3560 cm/g and 0.2662 cm/g, respectively; the specific surface area of micropores and the mean pore diameter expanded from 361.15 m/g and 2.0975 nm to 449.92 m/g and 2.1268 nm, respectively. The biological activity increased from 0.0297 mgO/gC·h to 0.0521 mgO/gC·h, while the biomass decreased from 203 nmolP/gC to 180 nmolP/gC. The results of high throughput 16S rRNA gene amplicon sequencing showed that microorganisms such as Clostridia and Nitrospira were markedly decreased due to high frequency ultrasound. The method used in this study caused the inhibition of certain carbon-attached microbials resulting in a negative effect on the removal rate of ammonia-N during the initial stage of the long-term reuse operation. The removal of UV254 and atrazine were restored from 8.1% and 55% to 21% and 76%, respectively.

Single-step synthesis of eucalyptus sawdust magnetic activated carbon and its adsorption behavior for methylene blue

“…The adsorption capacity of iodine, methylene blue, phenol and the iron content of the prepared MAC were determined according to the test methods for wooden activated carbon described in the National Standard of China, [31][32][33][34] GB/T 12496.8-2015, GB/T 12496.10-1999, GB/T 12496.12-1999 and GB/T 12496.19-2015, respectively.…”

Comparison of Nitrogen Removal Efficiencies and Microbial Communities of Full-Scale Anaerobic, Anoxic and Aerobic Processes in Municipal Wastewater Treatment Plants having Low and High COD/TN Ratios

“…Qian et al [22] found decreasing of Nitrospira from 0.44% to 0.04% by DO level of 0.8-1.5 mg-O 2 L -1 with SRTs between 33 and 56 d and NH 4 + 105 mg-N/L. While Sun et al [23] set a short SRT of 15 d with DO concentration at 1.0 and 2.0 mg-O 2 L -1 that increased 1.81 and 2.99%, respectively. Under the longer SRT (30 d) with the DO level (0.7-1.1 mg-O 2 L -1 ) at TH1 presented low abundance of Nitrospira than Nitrobacter, while the three plants with the shorter SRT (17 to 26 d) and higher DO level of 2.4 -4.5 mg-O 2 L -1 presented high abundance of Nitrobacter than Nitrospira.…”

Efficacies of Nitrogen Removal and Comparisons of Microbial Communities in Full-Scale (Pre-Anoxic Systems) Municipal Water Resource Recovery Facilities at Low and High COD:TN Ratios

“…During the collection of all samples of this work, the temperature was recorded from 18.5 to 28 • C. For this reason, the optimal temperature ranges for Nitrobacter and Nitrospira growth are not exactly reported. Huang et al [7] concluded that Nitrobacter was the favorable species under the temperature ranges of 24-25 • C while Nitrospira dominated at a relatively high temperature range of 29-30 • C. On the contrary, Alawi et al [34] indicated that a lower temperature range of 10-20 • C was the optimum condition for Nitrospira growth.…”