Qian Sui

Occurrence and removal of pharmaceuticals, caffeine and DEET in wastewater treatment plants of Beijing, China

The occurrence and removal of 13 pharmaceuticals and 2 consumer products, including antibiotic, antilipidemic, anti-inflammatory, anti-hypertensive, anticonvulsant, stimulant, insect repellent and antipsychotic, were investigated in four wastewater treatment plants (WWTPs) of Beijing, China. The compounds were extracted from wastewater samples by solid-phase extraction (SPE) and analyzed by ultra-performance liquid chromatography coupled with tandem mass spectrometry (UPLC-MS/MS). Most of the target compounds were detected, with the concentrations of 4.4 ng L(-1)-6.6 microg L(-1) and 2.2-320 ng L(-1) in the influents and secondary effluents, respectively. These concentrations were consistent with their consumptions in China, and much lower than those reported in the USA and Europe. Most compounds were hardly removed in the primary treatment, while their removal rates ranging from -12% to 100% were achieved during the secondary treatment. In the tertiary treatment, different processes showed discrepant performances. The target compounds could not be eliminated by sand filtration, but the ozonation and microfiltration/reverse osmosis (MF/RO) processes employed in two WWTPs were very effective to remove them, showing their main contributions to the removal of such micro-pollutants in wastewater treatment.

Seasonal variation in the occurrence and removal of pharmaceuticals and personal care products in different biological wastewater treatment processes.

The occurrence of 12 pharmaceuticals and personal care products (PPCPs) in two wastewater treatment plants in Beijing was studied monthly over the course of one year. The removal of PPCPs by three biological treatment processes including conventional activated sludge (CAS), biological nutrient removal (BNR), and membrane bioreactor (MBR) was compared during different seasons. Seasonal variations of PPCPs in the wastewater influent were discrepant, while in the wastewater effluent, most PPCPs had lower concentrations in the summer than in the winter. For the easily biodegradable PPCPs, the performance of MBR was demonstrated to be more stable than CAS or BNR especially during winter months. Diclofenac, trimethoprim, metoprolol, and gemfibrozil could be moderately removed by MBR, while their removal by CAS and BNR was much lower or even negligible. Nevertheless, no removal was achieved regardless of the season or the treatment processes for the recalcitrant PPCPs. Studies on the contribution of each tank of the MBR process to the total removal of four biodegradable PPCPs indicated the oxic tank was the most important unit, whereas membrane filtration made a negligible contribution to their elimination.

Degradation of trichloroethylene in aqueous solution by calcium peroxide activated with ferrous ion.

The application of calcium peroxide (CaO2) activated with ferrous ion to stimulate the degradation of trichloroethylene (TCE) was investigated. The experimental results showed that TCE could be completely degraded in 5 min at a CaO2/Fe(II)/TCE molar ratio of 4/8/1. Probe compound tests demonstrated the presence of reactive oxygen species HO· and O2(-·) in CaO2/Fe(II) system, while scavenging tests indicated that HO· was the dominant active species responsible for TCE removal, and O2(-·) could promote TCE degradation in CaO2/Fe(II) system. In addition, the influences of initial solution pH and solution matrix were evaluated. It suggested that the elevation of initial solution pH suppressed TCE degradation. Cl(-) had significant scavenging effect on TCE removal, whereas HCO3(-) of high concentration showed favorable function. The influences of NO3(-) and SO4(2-) could be negligible, while natural organic matter (NOM) had a negative effect on TCE removal at a relatively high concentration. The results demonstrated that the technique of CaO2 activated with ferrous ion is a highly promising technique in in situ chemical oxidation (ISCO) remediation in TCE contaminated sites.

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.

Rapid photocatalytic degradation of PCP―Na over NaBiO3 driven by visible light irradiation

The photocatalytic performance of sodium pentachlorophenate (PCP-Na) over NaBiO(3) under visible light irradiation was first investigated systematically. After 1h of photocatalytic reaction, the degradation rate of PCP-Na could reach to 90.5% in appropriate conditions. OH is the dominant photooxidant rather than O(2)(-) based on the experiment results and density of states (DOS) analysis. The PCP-Na solution became basic (pH value increased to approximately 9) with the progress of photocatalytic reaction which may be attributed to the PCP(-) oxidized to the pentachlorophenoxy radical by an attack on PCP(-) by OH. The photocatalytic reaction over NaBiO(3) follows the rule of first-order reaction according to the Langmuir-Hinshelwood model. The initial concentration of the PCP-Na, the initial pH value of PCP-Na aqueous solution and the amount of NaBiO(3) used have great influences on the photocatalytic performance. Three kinds of photocatalytic systems (P25, Bi(2)O(3) and P25-Bi(2)O(3) heterojunction) exhibited relative lower photocatalytic activity compared to NaBiO(3) powder.

Coking wastewater treatment for industrial reuse purpose: Combining biological processes with ultrafiltration, nanofiltration and reverse osmosis

A full-scale plant using anaerobic, anoxic and oxic processes (A1/A2/O), along with a pilot-scale membrane bioreactor (MBR), nanofiltration (NF) and reverse osmosis (RO) integrated system developed by Shanghai Baosteel Chemical Co. Ltd., was investigated to treat coking wastewater for industrial reuse over a period of one year. The removals reached 82.5% (COD), 89.6% (BOD), 99.8% (ammonium nitrogen), 99.9% (phenol), 44.6% (total cyanide (T-CN)), 99.7% (thiocyanide (SCN-)) and 8.9% (fluoride), during the A1/A2/O biological treatment stage, and all parameters were further reduced by over 96.0%, except for fluoride (86.4%), in the final discharge effluent from the currently operating plant. The pilot-scale MBR process reduced the turbidity to less than 0.65 NTU, and most of the toxic organic compounds were degraded or intercepted by the A1/A2/O followed MBR processes. In addition, parameters including COD, T-CN, total nitrogen, fluoride, chloride ion, hardness and conductivity were significantly reduced by the NF-RO system to a level suitable for industrial reuse, with a total water production ratio of 70.7%. However, the concentrates from the NF and RO units were highly polluted and should be disposed of properly or further treated before being discharged.

Perchloroethylene (PCE) oxidation by percarbonate in Fe2+-catalyzed aqueous solution: PCE performance and its removal mechanism

The performance of Fe(2+)-catalyzed sodium percarbonate (SPC) stimulating the oxidation of perchloroethylene (PCE) in groundwater remediation was investigated. The experimental results showed that PCE could be completely oxidized in 5 min at 20 °C with a Fe(2+)/SPC/PCE molar ratio of 8/8/1, indicating the effectiveness of Fe(2+)-catalyzed SPC oxidation for PCE degradation. Fe(2+)-catalyzed SPC oxidation was suitable for the nearly neutral pH condition, which was superior to the conventional Fenton oxidation in acidic condition. In addition, the investigations by using hydroxyl radical scavengers and free radical probe compounds elucidated that PCE was degraded mainly by hydroxyl radical (HO) oxidation in Fe(2+)/SPC system. In conclusion, Fe(2+)-catalyzed SPC oxidation is a highly promising technique for PCE-contaminated groundwater remediation, but more complex constituents in groundwater should be carefully considered for its practical application.

Degradation of carbon tetrachloride in aqueous solution in the thermally activated persulfate system

Thermal activation of persulfate (PS) has been identified to be effective in the destruction of organic pollutants. The feasibility of carbon tetrachloride (CT) degradation in the thermally activated PS system was evaluated. The experimental results showed that CT could be readily degraded at 50 °C with a PS concentration of 0.5M, and CT degradation and PS consumption followed the pseudo-first order kinetic model. Superoxide radical anion (O2(*-)) was the predominant radical species responsible for CT degradation and the split of CCl was proposed as the possible reaction pathways for CT degradation. The process of CT degradation was accelerated by higher PS dose and lower initial CT concentration. No obvious effect of the initial pH on the degradation of CT was observed in the thermally activated PS system. Cl(*-), HCO3(*-), and humic acid (HA) had negative effects on CT degradation. In addition, the degradation of CT in the thermally activated PS system could be significantly promoted by the solvents addition to the solution. In conclusion, the thermally activated PS process is a promising option in in-situ chemical oxidation/reduction remediation for degrading highly oxidized organic contaminants such as CT that is widely detected in contaminated sites.

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.