Synthesis of a novel humic acid-based polycarboxylic dispersant for coal water slurry

A novel humic acid-based polycarboxylic-type (HAP) dispersant for coal–water slurry (CWS) was successfully synthesized in aqueous solution from the copolymerization of HA, acrylic acid and maleic acid. The structure of HAP was characterized by Fourier transform infrared (FTIR), thermogravimetry (TG) and ¹H NMR. With HAP as a dispersant for Linfen coal slurry, the effects of the mass ratio of HA and monomer, initiator concentration, reaction temperature and reaction time on the HAP dispersant performance were discussed by examining the apparent viscosity of CWS. The results showed that CWS prepared withHAP dispersant performed excellent dispersity and stability. When the dosage of HAP was up to 0.5 wt.%, the apparent viscosity of CWS was 505 mPa·s. Experiments on the stability of CWS containing 0.5 wt.% HAP demonstrated that the penetration ratio reached 85.45 % after 96 h, which was higher by 12.87 % than that of CWS prepared with HA. And the CWS produced with HAP had lower dewatering rate within the storage time, which was less 1.85 % than that of CWS with HA when the storage time was 72 h. Furthermore, the maximum coal content of CWS with 0.5 wt.% HAP may reached 70 wt.%. This work found a new route for utilizing humic acid and enlarged the selecting range of the dispersant for CWS. It has a positive significance for protection of environment.     

自养反硝化脱氮耦合沼气同步脱硫效能研究

污水深度脱氮问题日益突出,在实现污水深度脱氮的过程中尽可能降低运行成本更是符合目前我国的发展目标,因此,开发经济绿色的污水脱氮技术对可持续发展具有重大意义.本试验提出自养反硝化脱氮耦合沼气同步脱硫工艺,具有成本低,资源利用率高等优势.以沼气中的硫化氢作为电子供体,实现了污水中同步脱氮及沼气脱硫净化的耦合,并探究了上升流速、硫氮比对该工艺运行效能的影响.实验结果显示,以硫化氢代替硫化物作为电子供体参与反硝化,对工艺脱氮效能无明显影响,在低硝酸盐负荷条件下运行时,污水脱氮效能不受气体上升流速及硫氮比的影响,均能达到100%.而本工艺的脱硫效能受上升流速影响较小,受硫氮比影响较大.在不同上升流速下,硫化氢去除率均为100%.在硫氮比为5∶8时,硫化氢100%转化为硫酸盐;硫氮比为5∶5时,硫化氢去除率为99.1%,单质硫产率约为30%;硫氮比为5∶2,回流比为1∶1时,硫化氢去除率最高可达91%,单质硫产率为77%.本试验可为后续自养反硝脱氮同步沼气脱硫工艺参数优化及应用的拓展提供理论依据和参考.     

碱后处理对互花米草沼渣理化特性的影响研究

以互花米草厌氧发酵后的沼渣为原料,采用紫外扫描、FTIR、XRD、1H-NMR、13C-NMR和其他一些常规分析手段研究了5%NaOH溶液固态处理前后,互花米草沼渣的物质结构、物质组成以及水浸提液理化特性的变化.结果表明,经5%的NaOH溶液处理48 h后,互花米草沼渣的骨架结构并未受到破坏,只是某些官能团的结构受到破坏;碱处理后,互花米草沼渣中木质素碎片化,木质素的芳香环结构受到不同程度的破坏,但木质素含量稍有增加;碱处理破坏了互花米草沼渣中纤维素的结晶结构,形成可被厌氧微生物破坏的类似结晶区结构,结晶区的比例增加,纤维素相对含量增加;碱处理后,互花米草沼渣中羧酸盐破坏严重,沼渣中羧基碳含量降低,烷烃类物质也受到一定的破坏,半纤维素相对含量降低;碱处理后,互花米草沼渣中烷基碳和芳香碳含量均降低,烷氧碳含量增加,芳香度降低,表明碱处理后互花米草沼渣的脂肪族特性增强,可生物降解性能提高.     

农田施用沼液的重金属污染评价及承载力估算——以江苏滨海稻麦轮作田为例

以江苏滨海稻麦轮作田为对象，研究沼液施用0，3，5a对土壤和作物籽粒重金属（Cu、Zn、Pb、Cd）含量的影响，评价其污染风险并估算农田沼液承载力.结果表明：沼液施用3，5a后，土壤和作物籽粒中Cu、Zn、Pb、Cd均未超标，内梅罗指数与土壤和农产品综合质量指数显示农田重金属污染程度属于清洁.土壤Cu和Zn显著富集，沼液施用5a后，小麦季土壤Cu、Zn含量分别为22.59，63.08mg/kg，较未施用分别提高了19.52%和28.89%.水稻季土壤Cu、Zn含量分别为26.12，78.74mg/kg，较未施用分别提高了27.73%和31.80%.小麦和水稻籽粒Zn含量随沼液施用年限增加而增加（P<0.05），沼液施用5a分别达到25.07，30.98mg/kg，较未施用分别提高了23.50%和16.29%.小麦季和水稻季0~15cm土壤中Cu的累积速率分别为0.74，1.13mg/（kg·a），Zn的累积速率分别为2.83，3.80mg/（kg·a）.基于土壤重金属累积速率，江苏滨海稻麦轮作田沼液安全施用年限为63a.     

堆沤处理对稻草厌氧消化产气的影响

采用厌氧消化后的消化液对稻草进行堆沤预处理,设计正交试验L9(34),考察温度、含水率、混合液悬浮固体(MLSS)及时间对厌氧消化产气量的影响,并对堆沤处理前后的稻草进行了不同有机负荷率下的产气试验.结果表明,堆沤处理后稻草总产气量比未处理提高了3%～49.5%,最优条件组合为温度30 ℃、含水率900 g·kg-1、时间10 d、MLSS 1 500 mg·L-1.在此最优条件下,处理后稻草消化的单位挥发性固体产气量为804.8 mL·g-1,与未处理稻草相比提高51.2%,产气高峰提前10 d左右.     

阴离子膜矿浆电解回收干电池正极材料中的锰

研究了硫酸介质中阴离子膜矿浆电解回收废旧干电池正极材料中锰的工艺条件。实验结果表明,阴极室浸出锰离子的较佳条件为:电流密度150A/m2,酸度1.0mol/L,液固比8∶1,温度20℃。在此条件下恒电流电解90min,锰的回收率为25.77%,阴极表观电流效率为101.1%。经反应机理分析得出,在浸出前1h,反应的控制步骤为混合控制,1h后为化学反应控制,活化能为52.85kJ/mol。采用该法可实现资源的循环利用,具有环境和经济效益。     

Toxicity identification evaluation of anaerobically treated swine slurry: A comparison between Daphnia magna and Raphanus sativus

Anaerobic digestion does not efficiently reduce ionic compounds present in swine slurry, which could present a potential risk to aquatic ecosystems (surface runoff) and terrestrial ambient (irrigation). The objective of this study was to evaluate the ecotoxicological characteristics of anaerobically treated swine slurry using acute and chronic (epicotyl elongation) toxicity tests with Daphnia magna and Raphanus sativus and identification of suspected toxic compounds using the Toxicity Identification Evaluation (TIE) method. The evaluation was performed in three phases: physicochemical characterization of the slurry; acute/chronic toxicity testing with Daphnia magna and Raphanus sativus for each fraction of the TIE (cation and anion exchange columns, activated carbon, pH modification/aeration and EDTA) and identification of suspected toxic compounds. The anaerobically treated slurry contained concentrations of ammonium of 1,072 mg L^?1, chloride of 815 mg L^?1 and metals below 1 mg L^?1 with a D. magna acute toxicity (48h-LC₅₀) of 5.3% and R. sativus acute toxicity (144h-LC₅₀) of 48.1%. Epicotyl elongation of R. sativus was inhibited at concentrations above 25% (NOEC). The cation exchange reduced the toxicity and free ammonia by more than 90% for both bio-indicators. Moreover, this condition stimulated the epicotyl growth of R. sativus between 10% and 37%. In conclusion, the main compound suspected of causing acute toxicity in D. magna and acute/chronic toxicity in R. sativus is the ammonium. The findings suggest the need the ammonium treatment prior to the agricultural reuse of swine slurry given the high risk to contaminate the aquatic environment by runoff and toxicity of sensitive plants.     

小球藻(Chlorella vulgaris)净化沼液和提纯沼气

为了研究同时提纯沼气和净化沼液的可能,利用沼液作为小球藻(Chlorella vulgaris)的培养基,同时把沼气中的CO2作为小球藻培养的碳源。在无菌培养条件下,得出了最适生长条件为沼液浓度50%、初始pH值6.0、接种小球藻干重为0.20 mg/mL、光质为红光。在此条件下沼液中的COD、TN、TP和BOD5的去除率分别达到了88.5%、91.2%、95.3%和87.6%,沼气中甲烷含量由原先的40%提升到60.2%。很好地同时解决了沼气品质低下和高浓度污染物沼液污染环境的问题。     

预处理方法对水葫芦厌氧发酵产沼气的影响

水葫芦可作为厌氧发酵产沼气的原料。研究发现,水葫芦自身的生物特性会制约其产气潜力的发挥,而发酵前预处理有助于解决这一问题。以采自昆明滇池的新鲜水葫芦为研究对象,分别采用物理法(切分法、压榨法),化学法(酸处理法、碱处理法和金属离子处理法)和生物法(酶处理法)对其进行预处理,以预处理后的水葫芦为原料进行发酵产沼气实验。结果表明,金属离子处理的原料产气效果最佳,在中温35℃,进样浓度7.4%(TS)时,其原料TS产气率、平均甲烷浓度和原料容积产气率分别为744.55 m3/t、59.32%和0.144 m3/(m3·d),与切分处理原料相比提高了88%、13%和87%。其余处理方法也在不同程度上优化了水葫芦的产气效果。因此,以预处理的方式来提高水葫芦的生物利用率和产气效率是可行的。     

低浓度溶解氧下猪粪固体有机物水解产酸研究

本文以猪粪为发酵原料,通过批式实验研究不同溶解氧(DO)浓度(0—0.26 mg.L-1)、发酵时间(3—12 d)和挥发性固体(VS)浓度(11.14—111.35 g.L-1)对猪粪固体水解酸化过程的影响,确定了低DO浓度下固体有机物优化水解产酸工艺条件:中温35℃,初始VS浓度37.11 g.L-1,初期的DO浓度0.1—0.26 mg.L-1.在此条件下,发酵时间3 d,DO浓度下降到0.10 mg.L-1以下.猪粪发酵液pH值由7.45±0.10降低到5.86±0.17,VS降解率(25.67±1.20)%,挥发性脂肪酸(VFA)中乙酸(3895±91)mg.L-1、丙酸(2313±82)mg.L-1、正丁酸(1361±17)mg.L-1、正戊酸(540±11)mg.L-1.优化条件下的猪粪水解酸化液进行厌氧产甲烷发酵,发酵10 d内产气停止,低溶解氧水解酸化和厌氧产甲烷发酵累计时间仅为13 d,甲烷体积分数(69.5±0.2)%,VS产气率为(0.282±0.011)L CH.4g-1VS.研究结果表明,适当延长发酵时间能够增加VFA中乙酸的含量,初始VS浓度差异对发酵液VFA浓度和VS降解率的影响较显著,低溶解氧能够促进猪粪固体有机物水解过程.