Pretreatment of 3-hydroxyacetophenone in pharmaceutical wastewater using combined salting-out crystallization+ Fenton system and subsequent impact analysis of effluent water.

Selecting a suitable pretreatment process for pharmaceutical wastewater that is difficult to treat biochemically so that it can enter the subsequent biochemical treatment. In this study, pharmaceutical wastewater consisting of 45 g/L sodium bisulfate, 9 g/L 3-hydroxyacetophenone (3-HAP), and 36.75 g/L sulfuric acids,which is a kind of typical pharmaceutical wastewater, was used for the pretreatment case study, and the process was screened by technology. A salting-out crystallization+Fenton system(SC-F) was developed for the treatment of this wastewater. The salting-out agent is formed by the pH adjustment process without additional additions and the salting-out crystallization effect is significant for the precipitation of 3-HAP from the wastewater. Subsequently, the optimal operating conditions for SC-F were derived from experiments as H2O2 of 0.4692 mol/L, n(H2O2):n(Fe2+)=30:1, pH=3. Under optimal conditions, the reaction time of 2 h achieved a COD removal rate of 90% and a BOD/COD value of 0.56, confirming the effectiveness of the technology in treating this wastewater. Additionally, it was discovered that the Fenton treatment was not significantly impacted by the inorganic components of the effluent. Analysis of effluent properties and possible effects on subsequent treatment by LC-MS and toxicity analysis. The results show that the biodegradability are enhanced by the pretreatment technology. However, the effluent still suffers from high acidity and high salt content, and this study proposes a solution to this problem. Furthermore, research on the treatment of 3-HAP wastewater has not been reported and this study provides a new case study in the field of wastewater treatment.

Photodegradation performance and mechanism of sulfadiazine in Fe(III)-EDDS-activated persulfate system.

In order to overcome the shortcomings in the traditional Fenton process, Fe(III)-EDDS-activated persulfate advanced oxidation process under irradiation is carried out as a promising technology. The photodegradation of sulfadiazine (SD) in Fe(III)-EDDS-activated persulfate system was investigated in this paper. The results showed that SD could be effectively degraded in Fe(III)-EDDS/S2O82-/hv system. The effects of Fe(III):EDDS molar ratio, the concentration of Fe(III)-EDDS, and the concentration of S2O82- on SD degradation were explored. At neutral pH, when Fe(III):EDDS = 1:1, Fe(III)-EDDS = 0.1 mM, S2O82- = 1.5 mM, the best SD degradation was achieved. The experiment of external influence factors showed that the degradation of SD could be obviously inhibited by the presence of CO32-, SO42-, whereas the degradation of SD was almost unaffected by the addition ofCl-. The degradation of SD could be slightly inhibited by the presence of humic acid and NO3-. The effect of pH on SD degradation was investigated, and SD could be degraded effectively in the pH range of 3-9. ESR proved that 1O2, ·OH, SO4-, and O2- were produced in the process. SO4- and ·OH were identified as the main radicals while O2·- also played non-ignorable role. Eleven intermediate products of SD were analysed. The C = N, S-N, and S-C bonds of SD were attacked by radicals firstly, leading to a series of reactions that eventually resulted in the destruction of SD molecules and the formation of small organic molecules.

Direct start-up of aerobic granular sludge system with dewatered sludge granular particles as inoculant.

Aerobic granular sludge (AGS) is a promising technology for engineering applications in the biological treatment of sewage. New objective is to skip the conventional granulation step to integrate it into a continuous-flow reactor directly. This study proposed a method for integrating spherical pelletizing granular sludge (SPGS) into a new patented aerobic granular sludge bed (AGSB), a continuous up-flow reactor. AGSB system could be startup directly, and after 120 days of operation, the SPGS maintained a relatively intact spherical structure and stability. With an initial high chemical oxygen demand (COD) volume loading of over 2.0 kg/(m3·d), this system achieved the desired effect as the same as a mature AGS system. The final mixed liquid suspended solids, and the ratio of 30 min-5 min sludge volume index (SVI30/SVI5) were 20,000 mg/L, and 0.84, respectively. Although hydraulic elution and filamentous bacteria (FBs) had a slightly negative impact on initial phase pollutant removal, the final removal rates for COD, total nitrogen (TN), ammonia nitrogen (NH4+-H), and total phosphorus (TP) were 90%, 70%, 95%, and 85%, respectively. The presence of specific functional microorganisms promoted the secretion of extracellular polymeric substances (EPS), from 90.65 to 209.78 mg/gVSS. The maturation process of SPGS altered the microbial community structures and reduced the species abundance of microbes in sludge.