Wentao Zhao

Identification of priority pharmaceuticals in the water environment of China

In recent years, increasing attention has been paid to the trace-level contamination of pharmaceuticals in the water environment all over the world. Considering a large number of pharmaceuticals used, it is crucial to establish a priority list of pharmaceuticals that should be monitored and/or treated first. In the present study, we developed a ranking system based on the pharmaceutical consumption, removal performance in the wastewater treatment plants (WWTPs) and potential ecological effects, and applied to the situation of China. 39 pharmaceuticals, which had available consumption data and also been reported previously in the WWTPs of China, were selected as candidate pharmaceuticals. Among them, seventeen pharmaceuticals were considered as priority pharmaceuticals, out of which, erythromycin, diclofenac acid and ibuprofen, had the high priority. Compared with other literatures, we found that some pharmaceuticals given concerns to globally should also be included in the priority list in China; while some pharmaceuticals, not mentioned in other literatures, such as cefalexin, ketoconazole, should be also given prior consideration in China. Among all the therapeutic classes, antibiotics, which were grossly abused in China, contributed the most to the priority pharmaceuticals. However, priority antibiotics accounted for only 32% of candidate antibiotics, while 71% and 100% of the candidate anti-inflammatory and antilipidemic respectively were identified as the priority pharmaceuticals, indicating that antibiotics might be overanxiously considered in the previous studies on their behaviors in the WWTPs of China.

Pharmaceuticals and personal care products in the leachates from a typical landfill reservoir of municipal solid waste in Shanghai, China: Occurrence and removal by a full-scale membrane bioreactor

Knowledge on the pharmaceuticals and personal care products (PPCPs) in landfill leachates, which are an important source of PPCPs in the environment, was very limited. Hence, four sampling campaigns were conducted to determine eighteen PPCPs in the landfill leachates from a landfill reservoir in Shanghai. Five of the target PPCPs were first included in a landfill leachate study. Additionally, their removal from landfill leachates by a full-scale membrane bioreactor (MBR) was illustrated. The results showed fourteen out of eighteen PPCPs were detectable in at least one sampling campaign and achieved individual concentrations ranging from 0.39 to 349μg/L in the landfill leachates. Some PPCPs exhibited higher contamination levels than those reported in other countries. Good removal of PPCPs by MBR led to a largely reduced contamination level (<LOQ to 10.6μg/L) in the treated landfill leachates, which was, however, still much higher than those in municipal wastewaters in Shanghai. To the best of our knowledge, this is the first report on the removal of PPCPs in landfill leachates. The findings emphasized the necessity to further study the PPCPs in the landfill leachates in China and the requirement to enhance their removal in the landfill leachates.

Recent advances in pharmaceuticals and personal care products in the surface water and sediments in China

Pharmaceuticals and personal care products (PPCPs) have been regarded as an emerging problem in the surface water environment in the past few decades. In China, although related studies were initiated several years ago, an increasing number of studies on this topic have been conducted in recent years. These studies have expanded knowledge of their occurrence, behavior and associated risk in the surface water environment in China. This review compiles the most recent literature related to the studies of PPCPs in the surface water environment in China. It includes PPCP occurrence in surface water and sediments, their geographical distribution, and outcomes of the associated risk assessment. It shows that antibiotics have received much more attention in both surface water and sediments than other PPCPs. Compared to other countries; most antibiotics in the collected sediments in China showed higher contamination levels. Many more study areas have been covered in recent years; however, attention has been given to only specific areas. Environmental risk assessment based on risk quotients indicated that sulfamethoxazole presents the most significant environmental risk to relevant aquatic organisms; followed by ofloxacin, ciprofloxacin, enrofloxacin, 17α-ethynylestradiol, ibuprofen and diclofenac. Despite limited research on the environmental risk assessment of PPCPs in sediments, higher risks posed by PPCPs in the sediments rather than surface water were identified highlighting the need for further risk assessment of PPCPs in sediment samples.

Removal of pharmaceutical and personal care products by sequential ultraviolet and ozonation process in a full-scale wastewater treatment plant

The application of appropriate advanced treatment process in the municipal wastewater treatment plants (WWTPs) has become an important issue considering the elimination of emerging contaminants, such as pharmaceutical and personal care products (PPCPs). In the present study, the removal of 13 PPCPs belonging to different therapeutic classes by the sequential ultraviolet (UV) and ozonation process in a full-scale WWTP in Beijing was investigated over the course of ten months. Most of the target PPCPs were effectively removed, and the median removal efficiencies of individual PPCPs, ranging from − 13% to 89%, were dependent on their reaction rate constants with molecular ozone. Noticeable fluctuation in the removal efficiencies of the same PPCPs was observed in different sampling campaigns. Nevertheless, the sequential UV and ozonation process still made a significant contribution to the total elimination of most PPCPs in the full-scale WWTP, by compensating for the poor or fluctuant removal performance of PPCPs by biologic treatment process.

New insights into the enhanced performance of high solid anaerobic digestion with dewatered sludge by thermal hydrolysis: Organic matter degradation and methanogenic pathways

Two lab-scale high solid anaerobic digesters fed with untreated sludge (R1) and thermally hydrolyzed sludge (R2) were operated to investigate the influence of thermal hydrolysis pretreatment (THP) on the degradation of individual macromolecular organic components (MOCs), as well as the functional and metabolic responses of microbes during anaerobic digestion (AD). The degradation of MOCs was improved by THP at different rates, in which improved degradation of proteins (by 49.0%) and hemicelluloses (by 25.0%) were the main factors contributing to the increase in volatile solids (VS) reduction. However, no enhancement of final degradation extent of MOCs was observed. With a more densified microbial population, R2 was also enriched in genes involved in amino acid and carbohydrate metabolism, reflected in the enhanced degradation of proteins and carbohydrates. After THP, the methanogenic pathway shifted from strict acetoclastic methanogenesis to acetoclastic/hydrogenotrophic methanogenesis, consistent with the enhanced methane production and the increase of methane content.

Identification of New Oxidation Products of Bezafibrate for Better Understanding of Its Toxicity Evolution and Oxidation Mechanisms during Ozonation

Bezafibrate (BF), a frequently detected pharmaceutical in the aquatic environment, could be effectively removed by ozonation. However, the toxicity of treated water increased, suggesting the generation of toxic oxidation products (OPs). In this study, eight OPs of BF ozonation were identified using a LTQ Orbitrap hybrid mass spectrometer coupled with HPLC, and six of them have not been previously reported during BF ozonation. Based on the abundant fragments and high assurance of accurate molar mass, structure elucidation was comprehensively performed and discussed. Hydroxylation, loss of methyl propionic acid group, and Crigée mechanism were observed as the oxidation mechanisms of BF ozonation. The toxicity of identified OPs calculated by quantitative structure activity relationship indicated that three OPs were probably more toxic than the precursor compound BF. This result together with the evolution of identified OPs in the treated solutions, indicated that two OPs, namely N-(3,4-dihydroxyphenethyl)-4-chlorobenzamide and N-(2,4-dihydroxyphenethyl)-4-chlorobenzamide, were the potential toxicity-causing OPs during BF ozonation. To the best of our knowledge, this is the first attempt to identify toxicity-causing OPs during the BF ozonation.

The dependence of the methylation of mercury on the landfill stabilization process and implications for the landfill management

Mercury species and other chemical characteristics of the leachate from anaerobic and semi-aerobic landfills were analyzed to investigate the factors that control mercury methylation during the landfill stabilization process. At the early landfill stage, the total mercury (THg) and the monomethyl mercury (MMHg) released rapidly and significantly, the THg concentration of the semi-aerobic landfill leachate was obviously higher than that of the anaerobic landfill leachate, while compared with the semi-aerobic landfill, the MMHg concentration in the anaerobic landfill was higher. As the landfill time increased, both of THg and MMHg concentration decreased quickly, the THg concentration in the anaerobic landfill was much higher than that in semi-aerobic landfill, while the MMHg concentration in the anaerobic landfill was lower than that in the semi-aerobic landfill. Generally, the concentrations of dimethyl mercury (DMHg) in the anaerobic landfill leachate were slightly higher than in the semi-aerobic landfill leachate during the stabilization process. A significant positive correlation was found between the DMHg concentrations and the pH value in anaerobic landfill leachate, but this correlation was opposite in the semi-aerobic landfill. The oxidative-reductive potential (ORP) condition was found to be the controlling factor of the methylation process during the early stage. However, the chemical characteristics, especially the TOC concentration, appeared to be the dominant factor affecting the methylation process as the landfill time increased.

Efficient elimination of sulfonamides by an anaerobic/anoxic/oxic-membrane bioreactor process: Performance and influence of redox condition

Membrane bioreactors (MBRs) were shown contradictory results for the removal of antibiotics, such as sulfonamides (SAs), from wastewater in different studies, which highlighted the necessity for comprehensive investigation on removal mechanisms of sulfonamides in well-controlled lab-scale MBRs. In the present study, the removal performance of nine SAs by a lab-scale anaerobic/anoxic/oxic-membrane bioreactor (A1/A2/O-MBR) was studied at environmental relevant concentrations. The results showed that all the SAs were efficiently eliminated (93.9%-97.5%) in the A1/A2/O-MBR, much more efficiently than the previously reported MBR-based processes. The largest contribution to the total removal was made by the aerobic reactor (71.1%-85.3%) A small portion of SAs (7.1%-22.5%) were removed by anoxic reactor. Activated sludge in the A1/A2/O-MBR was harvested to conduct batch experiments to further study the removal and degradation kinetics of SAs under anaerobic, anoxic and aerobic conditions. The results indicated that only sulfisoxazole could be removed under anaerobic condition. Modest biodegradation of individual SAs (15-33%) was observed under anoxic condition. Under aerobic condition, most investigated SAs underwent an efficient and fast removal (68-77%) in 6h without a lag phase; while sulfisomidine and sulfamethazine were removed less efficiently (approximately 47% after 6h reaction). The aerobic and anoxic degradation of SAs fitted the first-order kinetics model well, and the obtained biodegradation rate constants (k1) were reliable to predict removal efficiencies of SAs in the anoxic and aerobic reactor of A1/A2/O-MBR based on their HRTs.

Effect of effluent organic matter on ozonation of bezafibrate

The influence of three effluent organic matter (EfOM) model compounds, humic acid (HA), bovine serum albumin (BSA), and sodium alginate (AGS), on the ozonation of bezafibrate (BF), a typical pharmaceutical and personal care product (PPCP), was investigated. The results show that ozonation efficiently removed BF from aqueous solution with removal efficiencies > 95% within 8 min for all conditions. The reaction rate of BF decreased with increasing model compounds concentrations and the influence was more pronounced for HA and BSA, while less pronounced for AGS. Although BF concentration was significantly reduced, the degree of mineralization achieved was only approximately 11%. The addition of HA and BSA improved the mineralization of the solution, while the influence of AGS was minor. The acute toxicity of BF solution during ozonation was determined using the Luminescent bacteria test, and the toxicity exhibited an initial increase and a successive reduction. An overall decreased acute toxicity was observed with an increase of HA. The presence of BSA increased the formation rate of toxicity intermediates and resulted in inhibition peak forward.

Removal and fate of polycyclic aromatic hydrocarbons in a hybrid anaerobic–anoxic–oxic process for highly toxic coke wastewater treatment

Elimination of polycyclic aromatic hydrocarbons (PAHs) from coke wastewater is crucial to minimize the PAHs contamination levels to the environment. Knowledge about the characteristics of PAHs removal in biological treatment processes, especially hybrid systems, for real coke wastewater treatment has been very scarce. In this study, a lab-scale hybrid anaerobic-anoxic-oxic (A1/A2/O) process was used to treat highly toxic coke wastewater and operated more than 600 d at total hydraulic retention time (HRT) of 50 h, 40 h, 30 h, 20 h and internal mixed liquor recirculation ratio (R) of 3, 6, 9. Removal performance and behaviors of priority PAHs in the hybrid A1/A2/O system were investigated. The results showed that the appropriate total HRT and R from oxic reactor to anoxic reactor for organics and nitrogen removal was 40 h and 3, respectively. The concentrations of total PAHs were very high (254-488 μg/L) in the raw coke wastewater, and effectively reduced to 4.1-4.5 μg/L in the final effluent by the present system under the optimized operational conditions. Among the three treatment units, anoxic reactor made the largest contribution to the total PAHs removal. Large amounts of PAHs (415-1310 μg/g) were adsorbed to the activated sludge in the anoxic and oxic reactor, leading to a much higher load of PAHs (2535 μg/d) in the excess sludge than that in the treated coke wastewater (93 μg/d) at SRT 60 d. Therefore, the excess sludge was identified as the major emission source of PAHs in coke wastewater during the hybrid A1/A2/O process, and might pose an environmental risk if the excess sludge was not properly treated and disposed.