污水处理厂碳中和运行技术研究进展

全球变暖导致的自然灾害频发是当今世界关注的主要问题之一,各国纷纷制定了各自的碳中和目标。污水处理行业本应是绿色家族的一员,但如今却是碳排放和耗能大户,其低碳转型迫在眉睫。文中从节能和开源两个角度详细介绍了实现污水处理厂碳中和运行低碳转型的技术;如节能方面可以应用低能耗的碳氮两段法(新型AB工艺)、提高设备性能和设备运行的供需平衡;开源方面可以开发污水中的化学能和物理热能。研究可以为实现污水处理行业低碳转型提供借鉴。

Paddy Soil Stability and Mechanical Properties as Affected by Long-Term Application of Chemical Fertilizer and Animal Manure in Subtropical China

Wet stability, penetration resistance （PR）, and tensile strength （TS） of paddy soils under a fertilization experiment for 22 years were determined to elucidate the function of soil organic matter in paddy soil stabilization. The treatments included no fertilization （CK）, normal chemical fertilization （NPK）, double the NPK application rates （2NPK）, and NPK mixed with organic manure （NPK＋OM）. Compared with CK, Fertilization increased soil organic carbon （SOC） and soil porosity. The results of soil aggregate fragmentation degree （SAFD） showed that fast wetting by water was the key fragmentation mechanism. Among the treatments, the NPK＋OM treatment had the largest size of water-stable aggregates and greatest normal mean weight diameter （NMWD） （P ≤ 0.05）, but the lowest PR and TS in both cultivated horizon （Ap） and plow pan. The CK and 2NPK treatments were measured with PR 〉 2.0 MPa and friability index 〈 0.20, respectively, in the Ap horizon, suggesting that the soils was mechanically unfavourable to root growth and tillage. In the plow pan, the fertilization treatments had greater TS and PR than in CK. TS and PR of the tested soil aggregates were negatively correlated to SOC content and soil porosity. This study suggested that chemical fertilization could cause deterioration of mechanical properties while application of organic manure could improve soil stability and mechanical properties.

Inocula selection in microbial fuel cells based on anodic biofilm abundance of Geobacter sulfurreducens

Microbial fuel cells （MFCs） rely on microbial conversion of organic substrates to electricity. The optimal perfor- mance depends on the establishment of a microbial community rich in electrogenic bacteria. Usually this micro- bial community is established from inoculation of the MFC anode chamber with naturally occurring mixed inocula. In this study, the electrochemical performance of MFCs and microbial community evolution were eval- uated for three inocula including domestic wastewater （DW）, lake sediment （LS） and biogas sludge （BS） with varying substrate loading （Lsub） and external resistance （Rext） on the MFC. The electrogenic bacterium Geobacter sulfurreducens was identified in all inocula and its abundance during MFC operation was positively linked to the MFC performance. The IS inoculated MFCs showed highest abundance （18% ± 1%） of G. sulfurreducens, maximum current density [Imax = （690 ± 30） mA.m 2] and coulombic efficiency （CE = 29% ±1%） with acetate as the substrate./max and CE increased to （1780 ± 30） mA.m-2 and 58%± 1%, respectively, after decreasing the Rext from 1000 Ωto 200 Ω, which also correlated to a higher abundance ofG. sulfurreducens （21% ±0.7%） on the MFC anodic biofilm. The data obtained contribute to understanding the microbial community response to Lsub and Roy, for of timizing electricity eneration in MFCs.

The use of environmentally sustainable bio-derived solvents in solvent extraction applications——A review

Replacement of volatile organic compounds （VOCs） by greener or more environmentally sustainable solvents is becoming increasingly important due to the increasing health and environmental concerns as well as economic pressures associated with VOCs. Solvents that are derived from biomass, namely bio-derived solvents, are a type of green solvent that have attracted intensive investigations in recent years because of their advantages over con- ventional VOCs, such as low toxicity, biodegradability and renewability. This review aims to summarize the use of bio-derived solvents in solvent extraction applications, with special emphasis given to utilization of biodiesels and terpenes. Compared with the conventional VOCs, the overall performance of these bio-derived solvents is comparable in terms of extraction yields and selectivity for natural product extraction and no difference was found for metal extraction. To date most researchers have focused on laboratory scale thermodynamics studies. Future work is required to develop and test new bio-derived solvents and understand the kinetic performance as well as solvent extraction nilnt nlant studies.

Nondoped-type White Organic Light-Emitting Diode Using Star-Shaped Hexafluorenylbenzene as an Energy Transfer Layer

White organic light-emitting diodes （WOLEDs） with a structure of indium-tin-oxide （ITO）/N,N＇-bis- （1-naphthyl）-N,N＇-diphenyl- （1, 1＇-biphenyl）-4,4＇-diamine （NPB）/1,2,3,4,5,6-hexakis（9,9-diethyl-9H-fluoren-2- yl）benzene （HKEthFLYPh）/5,6,11,12-tetraphenylnaphtacene （rubrene）/tris（8-hydroxyquinoline） aluminum （Alq3）/Mg：Ag were fabricated by vacuum deposition method, in which a novel star-shaped hexafluorenyl- benzene HKEthFLYPh was used as an energy transfer layer, and an ultrathin layer of rubrene was inserted between HKEthFLYPh and Alq3 layers as a yellow light-emitting layer instead of using a time-consuming doping process. A fairly pure WOLED with Commissions Internationale De L＇Eclairage （CIE） coordinates of （0.32, 0.33） was obtained when the thickness of rubrene was 0.3 nm, and the spectrum was insensitive to the applied voltage. The device yielded a maximum luminance of 4816 cd/m2 at 18 V.

污水碳中和运行潜能分析

污水中含有有机物(COD)化学能和余温热能,但这种潜能一直不被重视。计算表明,污水所含化学能、热能理论值虽然前者小于后者,但相差倍数(3.0)不大,取决于进水COD浓度。然而,COD化学能在能量转化过程中有相当一部分并不能回收或受限于能量转化效率而不能全部转化。对某实际污水处理厂(COD=400 mg/L)潜能转化计算显示,污泥厌氧消化产甲烷(CH4)后实施热电联产(CHP)可转化的化学能折算电当量仅为0.20 k W·h/m^3,只能满足实际运行耗能(0.37 k W·h/m^3)的53.2%。因水源热泵可转换热能(全部出水,4℃温差)1.77 k W·h/m^3(供热)和1.18 k W·h/m^3(制冷),所以,只用不到15%的出水量(供热9.8%、制冷14.7%)即可弥补46.8%的碳中和运行赤字能量。总之,实例厂供热时出水热能与化学能所占总潜能值比例分别为90%和10%;折算电当量后,总潜能值为1.97 k W·h/m^3。

Reversible LiOH chemistry in Li-O_(2)batteries with free-standing Ag/δ-MnO_(2)nanoflower cathode

The low energy efficiency and poor cycle stability arising from the high aggressivity of discharge products toward organic electrolytes limit the practical applications of Li-O_(2)batteries(LOBs).Compared with the typical discharge product Li_(2)O_(2),LiOH shows better chemical and electrochemical stability.In this study,a free-standing cathode composed of hydrangea-likeδ-MnO_(2)with Ag nanoparticles(NPs)embedded in carbon paper(CP)(Ag/δ-MnO_(2)@CP)is fabricated and used as the catalyst for the reversible formation and decomposition of LiOH.The possible discharge mechanism is investigated by in situ Raman measurement and density functional theory calculation.Results confirm thatδ-MnO_(2)dominantly catalyzes the conversion reaction of discharge intermediate LiO_(2)*to LiOH and that Ag particles promote its catalytic ability.In the presence of Ag/δ-MnO_(2)@CP cathode,the LOB exhibits enhanced specific capacity and a high discharge voltage plateau under humid O_(2)atmosphere.At a current density of 200 mA g^(−1),the LOB with the Ag/δ-MnO_(2)@CP cathode presents an overpotential of 0.5 V and an ultra-long cycle life of 867 cycles with a limited specific capacity of 500 mA h g^(−1).This work provides a fresh view on the role of solid catalysts in LOBs and promotes the development of LOBs based on LiOH discharge product for practical applications.