观赏植物对沼液的净化效果

为研究观赏植物对沼液的净化能力,以滴水观音、水仙、红掌、白掌、万年青、绿萝、风信子为研究对象,通过沼液水培实验,对比分析了不同植物的生长特性及其对污染物的去除效果。结果表明,万年青、白掌、红掌和滴水观音的相对生长量和适应能力明显优于其他植物;随着处理时间的延长,大部分植物对COD的去除率呈增加趋势,最终达80%左右;在处理时间为7 d时,红掌、白掌和万年青对TN的去除率均达到80%以上;7种植物对沼液中TP的去除率在整个水培期间均未超过60%。各植物对污染物的去除效果均显著优于空白组(p0.05),且不同种类的植物之间差异明显(p0.05)。实验表明,万年青、红掌、白掌可作为处理沼液的备选观赏植物。     

猪场废水处理中的沼气热电联产工程案例分析

中高浓度畜禽废水处理中的沼气热电联产是保障沼气工程常年稳定运行的有效手段.以典型猪场废水处理沼气热电联产工程为案例,在工程介绍的前提下,引入相关数学模型,对沼气热电联产相关工艺参数进行了计算分析,结果表明,该工程沼气产量最高为1 678 m3/d,沼气发电机组发电效率为31.3％,发热效率为38.8％,总发电效率为70.1％,该沼气工程投资回报期为3.6年;CSTR厌氧罐秋季可达温度为24.3℃,冬季为15.9℃,CSTR厌氧罐内温度分布为秋季罐内平均温度(T)5.4(换热器顶部温度)=25.4℃,平均温度梯度grad1=1.83℃/m,grad2=0.80℃/m;冬季(T)5.4=19.6℃,(grad)1=1.44℃/m,(grad)2=1.06℃/m;通过参数分析,搅拌器宜尽可能置于换热器所在区域,并控制进水量稳定以保证CSTR厌氧罐的消化效果.     

pH值对玉米秸秆厌氧消化产气的影响

采用批式实验,研究了(35±0.5)℃、搅拌速度65 r/min的厌氧消化体系中,pH值对玉米秸秆厌氧消化产甲烷的影响,分析了消化液相及固相特性的变化.结果表明,厌氧消化第7～9天时各系统VFA浓度均达到最大值,pH值为7和9时,挥发性脂肪酸(VFA)浓度显著高于其他系统,SCOD向VFA的转化效率较高.pH值为9时累积产气量增加速度最快,最大累计产气量达到134.33 mL/g VS.pH值为7时累计产气量最大,高达149.2 mL/g VS,是pH值为5和11系统的3.23和6.71倍.pH值为7和9时,沼气中甲烷的平均含量分别为64.1％和62.5％,比pH值为5和11的系统提高了约10％.pH值为7和9时VS去除率达到67.68％和58.87％,显著高于其他系统.控制厌氧消化pH值在7～9范围内可以有效提高木质纤维素生物质的产气效率.     

The influence of dilute sulfuric acid pretreatment on biogas production from wheat plant

Dilute sulfuric acid pretreatment was used to improve the biomethane production from wheat plant (WP) via mesophilic anaerobic digestion. The pretreatments were performed at 121°C for different time durations of 10, 30, 60, and 120 min. The maximum methane yield of 302.4 mL/g volatile solids (VS) was obtained after the pretreatment for 120 min, which was 15.5% higher than that of the untreated WP. The highest amounts of lignin removal (15.2%) and xylan degradation (91.5%) were also achieved after this pretreatment. The pretreatment for 60 min enhanced the methane yield by 8.9%, while the pretreatments for 10 and 30 min had no positive effects on the methane yield. All of the pretreatments significantly removed the hemicelluloses. Moreover, the qualitative analysis of the untreated and pretreated WP structure showed significant reduction in the crystallinity index accompanied by the destruction of surface layers of WP structure after pretreatment.     

Biogas upgrading and utilization from ICEs towards stationary molten carbonate fuel cell systems

Biogas production from anaerobic digestion has increased rapidly in the last years, in many parts of the world, mainly due to its local scale disposition and to its potential on greenhouse gases (GHG) emissions mitigation. Biogas can be used as fuel for combined heat and power systems (CHP), in particular for internal combustion engines (ICEs). In recent investigations, fuel cells have been considered as alternative CHP systems. In the present article, two different energy conversion systems are compared: a 1.4 MW class MCFC system, running on pipeline natural gas, and an in situ ICE, running on biogas. In the first case, biogas is considered as a source fuel to obtain upgraded gas to be injected in the natural gas grid. In such scenario, the location of the fuel cell power plant is no longer strictly connected to the anaerobic digester site. Several energy balances are evaluated, considering different upgrading techniques and different biogas methane/carbon dioxide ratios.     

污泥厌氧消化的人工神经网络模型

基于污泥固体停留时间(SRT)为20 d的污泥中温厌氧消化实验,建立一个3层BP神经网络,以前1～20 d的进泥挥发性悬浮固体(VSS)、当天消化罐pH值和碱度共22个参数为输入,预测污泥消化系统日产气量,结果表明,网络具有良好的学习能力、泛化能力和辨识能力,能够较为准确地预测出系统日产气量.此外,根据进泥VSS不同,利用网络预测能力,调节pH值和碱度到合适的值,系统日产气量有明显提高,进一步证明了网络具有良好的预测能力和实用性.     

不同存放时间太湖蓝藻产沼气潜力

对不同存放时间蓝藻(新鲜蓝藻、存放3个月、6个月和9个月)进行厌氧消化处置,分析反应过程中沼气量、代谢产物和酶活等变化,获得各自的产沼气潜力。研究结果表明,存放6个月蓝藻组的产沼气率最大,为120.5 mL/g TS,是新鲜蓝藻组的1.29倍。Gompertz模型拟合表明,随着存放时间的延长,最大产沼气量(Pmax)先增大后减小,最大比产气率一直增加。存放3个月蓝藻组的VFA在第6天达到最大,为1 575.4 mg/L,而存放9个月蓝藻组的VFA在第2天达到最大,为1 116.5 mg/L。存放3个月蓝藻组的最大中性蛋白酶酶活为1 203.4μg/(g TS.h),比新鲜蓝藻组提高212.8μg/(gTS.h)。脱氢酶酶活随着蓝藻存放时间的增加呈现先增加后减小的趋势。     

生物氧化磁黄铁矿产生铁离子

从广东云浮矿山酸性废水中富集获得氧化亚铁硫杆菌(Thiobacillus ferrooxidans),利用该氧化亚铁硫杆菌研究了反应时间、pH、温度、矿浆浓度和矿物粒度对磁黄铁矿生物氧化获得铁离子的影响。结果表明,在29℃,摇床转速200 r/min,10%接种量条件下,氧化亚铁硫杆菌可以明显促进磁黄铁矿的氧化,但反应后期有黄钾铁矾沉淀生成,不利于获得铁离子;控制溶液pH值为2.00,温度在29～36℃范围,可促进生物氧化磁黄铁矿获得铁离子;铁离子量随着矿浆浓度的增大和矿物粒度的减小而增加,优化的矿浆浓度和矿物粒径分别为6%和58μm左右。     

Kinetics of the biodegradation pathway of endosulfan in the aerobic and anaerobic environments

The enriched mixed culture aerobic and anaerobic bacteria from agricultural soils were used to study the degradation of endosulfan (ES) in aqueous and soil slurry environments. The extent of biodegradation was ∼95% in aqueous and ∼65% in soil slurry during 15 d in aerobic studies and, ∼80% in aqueous and ∼60% in soil slurry during 60 d in anaerobic studies. The pathways of aerobic and anaerobic degradation of ES were modeled using combination of Monod no growth model and first order kinetics. The rate of biodegradation of β-isomer was faster compared to α-isomer. Conversion of ES to endosulfan sulfate (ESS) and endosulfan diol (ESD) were the rate limiting steps in aerobic medium and, the hydrolysis of ES to ESD was the rate limiting step in anaerobic medium. The mass balance indicated further degradation of endosulfan ether (ESE) and endosulfan lactone (ESL), but no end-products were identified. In the soil slurries, the rates of degradation of sorbed contaminants were slower. As a result, net rate of degradation reduced, increasing the persistence of the compounds. The soil phase degradation rate of β-isomer was slowed down more compared with α-isomer, which was attributed to its higher partition coefficient on the soil.     

用电石渣浆制备烟气脱硫剂

采用电石渣浆经处理后配制成的电石渣试样作为脱硫剂,对除尘后锅炉烟气进行脱硫实验,在烟气巾s与c质量比约为1：30、吸收体系pH为7～8、温度为15℃的条件下,平均脱硫率达96．35％。采用电石渣浆上层清液作脱硫剂对锅炉烟气进行脱硫的工业试验,在烟气流速为2．8～4．2m／s、脱硫塔内nCa：n5=1．2：1、体系pH为7～8的条件下,平均脱硫率达90．66％,且脱硫塔出气口处SO2质量浓度明显低于GB13271-2001《锅炉大气污染物排放标准》。