热处理时间对餐厨垃圾高温干式厌氧发酵的影响

餐厨垃圾中有机物大部分以大分子的形式存在,对其进行热处理,破坏大分子有机物的存在形式,将会影响其干式厌氧发酵的过程。实验对餐厨垃圾进行了热处理(100℃),处理后将其在含固率(TS)20%、接种率25%的条件下进行高温55℃厌氧发酵。实验结果表明,热处理后,餐厨垃圾的理化性质发生显著变化,累计产气量、TS和VS的去除率均增大。当热处理时间为15 min时,餐厨垃圾的SCOD值最高,为59.49 g/L,比未处理时提高了3.3倍。同样该条件下,累计产气量也最高,为2 782.8 m L,与未处理相比累积产气量提高58.30%,第二产气高峰比未处理提前3天。各发酵瓶发酵前后TS、VS去除率的变化趋势与累计产气量的变化基本一致,累计产气量越大,TS、VS的去除率越大。     

甲苯对UASB反应器中溶解性微生物产物的影响

以乙酸钠为外加碳源,考察了UASB反应器内甲苯对可溶性微生物产物（SMP）的影响。实验结果表明：低质量浓度（20~70 mg/L）的甲苯对微生物有刺激作用,使得污泥增殖速率变小,SMP的质量浓度也逐渐减少,经过一段时间的驯化后,系统COD和TOC的去除率分别达到93%和94%以上,下降趋势较小;较高质量浓度（70~200 mg/L）的甲苯对微生物有抑制作用,污泥活性下降,反应器运行状况开始恶化,SMP的质量浓度也逐渐增大,经过一段时间的驯化后,系统COD和TOC的去除率分别维持在81%和83%以上;当甲苯质量浓度超过200 mg/L时,表现为污泥活性严重下降,对COD的去除效果极差。     

臭氧氧化—包埋菌流化床生物处理组合工艺深度处理煤气化废水

采用臭氧氧化—包埋菌流化床生物处理组合工艺对煤气化废水进行深度处理。实验结果表明：当臭氧的质量浓度20 mg/L、臭氧进气流量1.5 L/min、臭氧通气时间30 min、包埋菌流化床水力停留时间24 h时,臭氧氧化工序的COD去除率达到30.0%~40.0%,总酚去除率达到100.0%;包埋菌流化床工序的COD去除率达到60.0%以上,氨氮的去除率大于95.0%;经组合工艺处理后,出水COD<60 mg/L,ρ（氨氮）<1.0 mg/L,ρ（总酚）未检出,色度小于50倍,达到GB8978—1996《污水综合排放标准》中的一级排放标准。     

用于石油污染土壤降解的高效降解菌的筛选及其降解条件优化

经过富集、分离优选出高效石油降解菌L-1,根据形态观察和生理生化特征初步鉴定为琼氏不动杆菌;采用单因素花盆实验模拟微生物原位修复并对其降解条件进行优化。结果表明,将高效石油降解菌应用于修复石油污染土壤,适宜接种量、表面活性剂浓度、CNP比、翻耕频率分别为15%、0.1%、100∶10∶1和1 d 1次;在该降解条件下修复28 d,可达到16.80%的石油降解率,远远高于土著微生物6.92%的降解率。     

降解SO2功能菌的16S rRAN基因测序及降解特性

用低浓度SO2诱导驯化方法获得高效脱硫菌群,并用分离培养与16S rRNA基因测序技术相结合的方法鉴定菌群种属,分析驯化过程中种群结构的动态变化,同时研究分离纯菌种的脱硫性能。结果表明,从诱导驯化7 d和14 d菌液中分别分离出23株菌和22株菌,16S rRNA序列分析发现这些菌归属于13个种,其中有6个种(Rhodococcus erythropolis、Pseudomonas putida、Microbacterium oxydans、Sphingomonas koreensis、Acinetobacter junii、Acinetobacter johnsonii)对SO2-3有较强的降解能力,并在持续驯化过程中稳定的生长传代,降解产物以硫酸根为主,还有极少量的单质硫。与含混合菌的驯化菌液降解SO2-3的能力相比,单一脱硫菌的脱硫性能较弱。脱硫功能菌株及其基本特性的研究为微生物处理SO2烟气提供了丰富的菌源信息和理论基础。     

厌氧系统中碱处理对污泥减量的影响

碱解预处理污泥和原污泥按一定比例进行混合后,投入厌氧反应器中进行消化,研究其对污泥减量化的影响。结果表明,该处理既可以提高污泥减量率,又能改善污泥厌氧消化性能,提高污泥产气量。当碱处理污泥和原污泥混合比为1∶3时,在混合初期由于稀释作用和水解中和作用,溶液的pH能迅速恢复到中性。SS减少48%,较对照组提高了10%;SCOD减少约80%,较对照组提高20%,而空白对照组因未发生溶胞作用,各参数值均处于较低水平,降解率也维持在较低水平。     

干式厌氧消化过程挥发酸对硫酸盐还原菌的影响

在牛粪干式厌氧消化过程中,通过添加不同挥发酸(乙酸、丙酸、丁酸),考察消化稳定阶段,挥发性脂肪酸的分布特征,挥发性脂肪酸酸组成变化对硫酸盐还原菌(SRB)的影响,微生物种群组成和种群间关系。实验结果表明,挥发性脂肪酸对SRB还原速率的贡献依次为:丙酸丁酸乙酸。相比乙酸和丁酸,添加一定量的丙酸,更有利于激活SRB的活性,从而加强SRB与产甲烷菌(MB)的种间协同,保证厌氧系统的稳定运行。     

利用白云石石灰去除与回收污泥厌氧消化液中氮和磷

以白云石石灰为实验材料去除与回收污泥厌氧消化液中的氮磷,通过小试实验研究不同投药固液比S/L、初始pH值、反应温度、搅拌速度及反应时间对去除与回收氮磷效果的影响。实验结果表明,在最佳投药固液比S/L为300mg/L,最佳初始pH值范围为8.5~9.5,反应温度为25.0℃,搅拌速度为150 r/min,反应时间为24 h条件下,氨氮(NH+4-N)和磷(PO3-4-P)的去除率分别为37.26%和89.60%。利用X射线衍射仪(XRD)、扫描电镜(SEM)对沉淀产物进行了表征,通过分析可知沉淀产物中含有磷酸铵镁(MAP),可实现废水中氮磷经济有效的回收。     

A novel use of anaerobically digested liquid swine manure to potentially control soybean cyst nematode

Experiments were carried out in two steps to determine the effect of anaerobically digested swine manure on soybean cyst nematode (SCN) egg control. In the first step, liquid swine manure underwent anaerobic digestion to search for the best digestion time for both volatile fatty acids (VFA) and ammonium nitrogen (NH₄ ⁺) enrichment. The results showed that about 17 and 28 days of incubation were needed, respectively, to reach the maximal levels of VFA and NH₄ ⁺ in the manure. In the second step, raw, VFA-enriched, and NH₄ ⁺-enriched manure were applied separately, at four different rates (25, 50, 100, and 200 mL/pot), to soil pots inoculated with nematode eggs in a greenhouse environment. Soil samples were collected 35 and 61 days after inoculation to determine the effect of such treated manure on SCN egg productivity. The data indicated that the SCN egg counts were inversely related to the manure application rates in a linear manner with correlation coefficients of 0.998, 0.967, and 0.900 for raw, NH₄ ⁺-enriched, and VFA-enriched manure for the 35-day samples. While no such relationships were found for the 61-day samples, implying that none of the treatments were still effective 61 days after application. At the four application rates, the VFA-enriched manure performed best in reducing SCN egg counts (by 18.1, 19.5, 34.3, and 18.6%) as compared to the raw manure treatment. In contrast, the NH₄ ⁺-enriched manure achieved mostly negative reductions. To achieve the best control of SCN egg growth, the VFA-enriched manure should be used and applied to soybean fields every 35 days.     

Impact of redox conditions on metolachlor and metribuzin degradation in mississippi flood plain soils

Abstract

The effect of soil redox conditions on the degradation of metolachlor and metribuzin in two Mississippi soils (Forrestdale silty clay loam and Loring silt loam) were examined in the laboratory. Herbicides were added to soil in microcosms and incubated either under oxidized (aerobic) or reduced (anaerobic) conditions. Metolachlor and metribuzin degradation under aerobic condition in the Forrestdale soil proceeded at rates of 8.83 ngd^‐1 and 25 ngd^‐1, respectively. Anaerobic degradation rates for the two herbicides in the Forestdale soil were 8.44 ngd^‐1 and 32.5 ngd^‐1, respectively. Degradation rates for the Loring soil under aerobic condition were 24.8 ngd^‐1 and 12.0 ngd^‐1 for metolachlor and metribuzin, respectively. Metolachlor and metribuzin degradation rates under anaerobic conditions in the Loring soil were 20.9 ngd^‐1 and 5.35 ngd^‐1. Metribuzin degraded faster (12.0 ngd^‐1) in the Loring soil under aerobic conditions as compared to anaerobic conditions (5.35 ngd^‐1).