吹脱-厌氧消化工艺处理养殖场废水

针对养猪场猪粪污水有机物浓度高,悬浮物浓度高,氨氮浓度高等特点,结合我国农村养殖场的地理位置等实际,设计采用物化除渣,生化降解有机物,吹脱除氨,沼气综合利用,粪渣用作农肥的工艺。有机物去除率高,出水水质稳定,实现了达标排放。

Simultaneous visible-light-induced hydrogen production enhancement and antibiotic wastewater degradation using MoS2@ZnxCd1-xS: Solid-solution-assisted photocatalysis

In this study,a ZnxCd1-xS solid solution was successfully synthesized using a hydrothermal method.MoS2 serving as a co-catalyst for hydrogen evolution was also prepared through a one-pot hydrothermal method.The structures,morphology,chemical states,and optical properties were characterized using powder X-ray diffraction,scanning electron microscopy,high-angle annular dark field-scanning transmission electron microscopy,elemental mapping,X-ray photoelectron spectroscopy,and UV-Vis diffuse reflection spectroscopy.Visible-light-driven photocatalytic experiments were conducted to simultaneously achieve hydrogen production and amoxicillin antibiotic wastewater degradation.The results indicated 8%MoS2/ZnxCd1-xS achieves the best photocatalytic performance.The ZnxCd1-xS samples illustrated a superior performance to that of CdS,which can be attributed to a thermodynamic improvement.Based on the results of PL and TRPL analyses,the enhancement of the hydrogen production mechanisms can be ascribed to the prolonged separation process of the photocarriers.Furthermore,the degradation results were analyzed using the HPLC method and the possible degradation pathways were determined through the HPLC-MS techniques.

Enhancing Biogas Production from Anaerobically Digested Wheat Straw Through Ammonia Pretreatment

Aqueous ammonia was used to pretreat wheat straw to improve biodegradability and provide nitrogen source for enhancing biogas production. Three doses of ammonia(2%, 4%, and 6%, dry matter) and three moisture contents(30%, 60%, and 80%, dry matter) were applied to pretreat wheat straw for 7 days. The pretreated wheat straws were anaerobically digested at three loading rates(50, 65, and 80 g·L-1) to produce biogas. The results indicated that the wheat straw pretreated with 80% moisture content and 4% ammonia achieved the highest methane yield of 199.7 ml·g-1(based on per unit volatile solids loaded), with shorter digestion time(T80) of 25 days at the loading rate of 65 g·L-1compared to untreated one. The main chemical compositions of wheat straw were also analyzed. The cellulose and hemicellulose contents were decomposed by 2%-20% and 26%-42%, respectively,while the lignin content was hardly removed, cold-water and hot-water extracts were increased by 4%-44%, and12%-52%, respectively, for the ammonia-pretreated wheat straws at different moisture contents. The appropriate C/N ratio and decomposition of original chemical compositions into relatively readily biodegradable substances will improve the biodegradability and biogas yield.

Photodegradation of methylmercury in the water body of the Three Gorges Reservoir

Biogeochemical cycling of mercury in the young Three Gorges Reservoir （TGR）, China, is strongly considered. Although methylmercury （MMHg） photodegradation （PD） is an important process involved in mercury cycling in this zone, little is known about this process. In situ incubation experiments were therefore performed to quantify the effect of different wave- length radiations and environmental factors on the PD process of MMHg in the water bodies of TGR. It was found that the ef- fect of solar radiation on MMHg PD was highly dependent on wavelength and water depth. All PD-rate constants resulting from each wavelength range decreased rapidly with water depth. For surface water, UV-A radiation （320-400 nm） was the key driver, accounting for 49%-62% of MMHg PD. For the entire water column, both photosynthetically active radiation （PAR, 400-700 nm） and UV-A were responsible for MMHg PD. MMHg PD fluxes peaked in summer （7.5-18 ng m-2 d-1）, followed by spring （3.3-8.0 ng m-2 d-1）, autumn （1.0-2.7 ng m-2 d-1）, and winter （0.060-0.15 ng m-2 d-1）. The annual fluxes of MMHg PD were estimated to be 1.1-2.8 μg m-2 at. Filtering the reservoir water and amending it with chemicals （i.e., CV, NO C, and dissolved organic matter （DOM）） showed significant effects on MMHg PD rate constants. Stepwise regression analysis showed that intensity of solar radiation, suspended particulate matter （SPM）, DOM, CI-, and NO3- were involved in the PD process. Path analysis clarified the relationship between MMHg PD rate constants and environmental variables, as well as the comparative strength of direct and indirect relationships among variables. The results are of great importance for understanding MMHg cycling characteristics in TGR and also facilitate the understanding of the underlying process, MMHg PD, in natural waters.