[Enhancement Effects and Mechanisms of Microscale Zero Valent Iron on the Performance of Anaerobic Co-digestion of Waste Activated Sludge and Food Waste]

Focusing on low biogas yields in the anaerobic co-digestion of waste activated sludge and food waste, the enhancing effects and mechanisms of microscale zero valent iron (mZVI) on anaerobic co-digestion was investigated. The results indicated that the addition of mZVI enhanced the methanogenesis stage of co-digestion but had no significant effect on the solubilization, hydrolysis, and acidification stages. With a dosage of 10 g·L^-1 mZVI, the cumulative methane yield (based on VS) within 15 days reached 238.68 mL·g^-1, which was 20.05% higher than the control group. The mechanism analysis showed that mZVI promoted electron transport system (ETS) activity (based on INTF/TS), which increased to 21.50 mg·(g·h)^-1 with 10 g·L^-1 mZVI compared to 13.43 mg·(g·h)^-1 in the control group. Furthermore, mZVI enhanced direct interspecies electron transfer (DIET) between specific bacteria and methanogens. Microbial community analysis demonstrated that the abundance of DIET-related microorganisms, such as Syntrophomonas, Methanosarcina, and Methanobacterium, was higher in presence of mZVI.

Catalytic degradation of ciprofloxacin by a visible-light-assisted peroxymonosulfate activation system: Performance and mechanism

Peroxymonosulfate (PMS) is extensively used as an oxidant to develop the sulfate radical-based advanced oxidation processes in the decontamination of organic pollutants and various PMS activation methods have been explored. Visible-light-assisted PMS activation to construct a Fenton-like process has shown a great potential for pollution control. In our work, BiVO₄ nanosheets were prepared using a hydrothermal process and used to activate PMS under visible light. A rapid degradation of ciprofloxacin (CIP) was achieved by dosing PMS (0.96 g/L), BiVO₄ (0.32 g/L) under visible light with a reaction rate constant of 77.72-fold higher than that in the BiVO₄/visible light process. The electron spin resonance and free radical quenching experiments indicate that reactive species of ^•O₂^-, h⁺, •OH and SO₄^•- all worked, where h⁺, •OH and SO₄^•- were found as the dominant contributors to the CIP degradation. The spectroscopic analyses further demonstrate that the photoinduced electrons were directly involved in the PMS activation process. The generated ^•O₂^- was partially utilized to activate PMS and more •OH was produced because of the chain reactions between SO₄^•- and H₂O/OH^-. In this process, PMS acted as an electron acceptor to transfer the photo-induced charges from the conduction band of BiVO₄ and PMS was successfully activated to yield the high-powered oxidative species. From the degradation intermediates of CIP detected by a liquid-chromatography-mass spectrometer, the possible degradation pathways were proposed. The substantially decreased toxicity of CIP after the reaction was also observed. This work might provide new insights into the visible-light-assisted PMS activation mechanisms and is useful to construct environmentally-friendly catalytic processes for the efficient degradation of organic pollutants.

Remediation of organochlorine pesticides contaminated lake sediment using activated carbon and carbon nanotubes

Organochlorine pesticides (OCPs) in sediment were a potential damage for humans and ecosystems. The aim of this work was to determine the effectiveness of carbon materials remedy hexachlorocyclohexane (HCH) and dichlorodiphenyltrichloroethanes (DDTs) in sediment. Two different carbon materials including activated carbon (AC) and multi-walled carbon nanotubes (MWCNTs) were used in the present research. Sediment treated with 2 wt% AC and MWCNTs after 150 d contact showed 97%, and 75% reduction for HCH, and 93% and 59% decrease for DDTs in aqueous equilibrium concentration, respectively. Similarly, the reduction efficiencies of DDT and HCH uptake by semipermeable membrane devices (SPMDs) treated with AC (MWCNTs) were 97% (75%) and 92% (63%), respectively under the identical conditions. Furthermore, for 2 wt% AC (MWCNTs) system, a reduction of XAD beads uptake up to 87% (52%) and 73% (67%) was obtained in HCH and DDT flux to overlying water in quiescent system. Adding MWCNTs to contaminated sediment did not significantly decrease aqueous equilibrium concentration and DDTs and HCH availability in SPMDs compared to AC treatment. A series of results indicated that AC had significantly higher remediation efficiency towards HCH and DDTs in sediment than MWCNTs. Additionally, the removal efficiencies of two organic pollutants improved with increasing material doses and contact times. The greater effectiveness of AC was attributed to its greater specific surface area, which was favorable for binding contaminants. These results highlighted the potential for using AC as in-situ sorbent amendments for sediment remediation.

Combined intramuscular-intradermal protocol of universal neonate HB vaccination irrespective of mother's status of HBsAg

To evaluate a protocol of combined intramuscular-intradermal (i.m.-i.d.) universal hepatitis B (HB) vaccination of neonates regardless of the mothers' HB surface antigen HBsAg status, 160 full-term newborn babies were sequentially divided into groups A and B (test and control groups). The group A babies were immunized by giving 30 micrograms HB vaccine i.m. within 24 h after birth and 2 micrograms i.d. twice at 1 and 6 months of age. Group B babies were immunized by giving one initial dose of 30 micrograms i.m. and two booster doses of 10 micrograms i.m. after same 0, 1, 6-month schedule. Blood samples were collected at birth before the first dose of the HB vaccine, at 6 months of age before the third dose and at 12 months. The blood samples were tested for HBsAg and anti-HBs by using Abbott RIA reagents. All of the 160 newborns received three doses of vaccine, but in only 96 of them was the blood examination completed. The positive rate of anti-HBs > 10 IU l-1 was 76.27 and 83.08% in groups A and B, respectively at 6 months, and 83.72 and 92.45%, respectively at 12 months. The geometric mean titres (GMT) of anti-HBs was 42.25 and 60.25 IU l-1 in groups A and B, respectively at 6 months, and 74.45 and 87.1 IU l-1, respectively at 12 months. HBsAg was negative in the two groups 6 and 12 months after birth. The chi 2 and t-tests showed there were no significant differences in these data between the two groups. Thus was it demonstrated that the combined i.m.-i.d. protocol using 34 micrograms of HB vaccine can produce a protection similar to that of the conventional 50 micrograms i.m. regimen, while ca on-third of the vaccine can be saved. The new protocol is theoretically rational and may be ideal according to the cost-effectiveness principle.

Cryptosporidium infection and diarrhea in rural and urban areas of Jiangsu, People's Republic of China

Screening of infants and children under age 15 years for Cryptosporidium oocysts in their stools was carried out in the suburb of Xuzhou City and six rural areas of Jiangsu Province. The infection rate varied from 0.7 to 5.06%. Of the total of 5,089 children examined, 89 (1.75%) were oocyst positive. The incidence was evidently higher in the group of children under age 4 years than it was in children from 4 to 15 years (P less than 0.01). Routine blood examination and immunoassay performed on blood samples from some of the infected children indicated that more than half of them had anemia and lower cellular immunity. Diarrhea was the main symptom of cryptosporidiosis. It was intermittent or persistent and was present in 57 of the 89 children positive for Cryptosporidium oocysts, while the other 32 children were asymptomatic carriers. Examination of stool specimens of adult members and domestic animals of about half of the infected families showed that two mothers, one pig, and one dog were positive for Cryptosporidium oocysts.