The specific filtration resistance, moisture, and SVI were used to evaluate the influence of pH on the filtration and dewatering efficiencies when applying Fenton's reagent to treat the excess sludge. The excess sludge used in this study was obtained from the wastewater treatment plant of An-Ping Industrial Park in Tainan, Taiwan. Results show that initial pH has no significant effect on the filtration efficiency of sludge by using the Fenton (Fe2+/H2O2) system as the treatment process. However, the reduction of specific resistance by Fenton-like (Fe3+/H2O2) process decreased suddenly to a level similar to that obtained from the control experiment at initial pH > 4.5. For the moisture of cake sludge, both Fenton and Fenton-like systems have the same tendency; the moisture of cake sludge increased slightly with increasing the initial pH. The SVI values for Fenton process decreased with increasing the initial pH, but the opposite result was obtained from the Fenton-like and control system; higher pH was not favorable for the sludge settling.
Due to lack of proper regulation, information about antibiotics consumption in many countries such as China is difficult to obtain. In this study, a simple method based on wastewater-based epidemiology was adopted to estimate their usage in four megacities of China. Six antibiotics (norfloxacin, ofloxacin, sulfamethoxazole, trimethoprim, erythromycin and roxithromycin), which are the most frequently consumed antibiotics in China, were selected as the targets. Based on our results, Chongqing had the largest total annual consumption of the selected six antibiotics among the four megacities, followed by Guangzhou, then Hong Kong, with Beijing having the least, with values of 4.4 g/y/P, 4.0 g/y/P, 1.6 g/y/P, and 1.3 g/y/P, respectively. Compared with the daily consumption per capita in Italy, the estimated consumption levels of the selected six antibiotics in four cities of China were 12-41 times those of Italy. Our results suggested that the consumption of antibiotics in China was excessive.
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