Characterization of the Effect of Programmed Aeration on Energy Efficiency of Microalgae Cultivation System

With autotrophic microalgae cultivation,?we can feed back the CO2?content of process streams and we can get lots of valuable organic compounds, among others biofuel components. For the production of energy source,we must reckon with the energy balance of the whole process. Densification and processing of microalgae can consume 50% - 70% of the energy that can be extracted from the cells,?therefore the cultivation should use such a little energy as it possible. In closed cultivation systems,?there are three main energy intensive steps: artificial illumination, dissolution of gas compounds and mixing. We have carried out our measurements in our lab-scale screening photobioreactor system for the investigation of the most energy effective program for aeration. We have found the aeration program considerable solution for lower energy consumption in?algae cultivation.

The acceleration degradation processes of different aged refuses with the forced aeration for landfill reclamation

Forced aeration is one of the promising ways to accelerate landfill reclamation,and understanding the relation between aeration rates and waste properties is the prerequisite to implementing forced aeration under the target of energy saving and carbon reduction.In this work,landfill reclamation processes with forced aeration were simulated using aged refuses(ARs)of 1,4,7,10,and 13 disposal years,and the potential of field application was also investigated based on a field project,to identify the degradation rate of organic components,the O_(2)consumption efficiency and their correlations to microbes.It was found that the removal rate of organic matter declined from 20.3%(AR_(1))to 12.6%(AR_(13)),and that biodegradable matter(BDM)decreased from 5.2%to 2.4%at the set aeration rate of 0.12 L O_(2)/kg waste(Dry Matter,DM)/day.A linear relationship between the degradation rate constant(K)of BDM and disposal age(x)was established:K=−0.0002193x+0.0091(R^(2)=0.854),suggesting that BDM might be a suitable indicator to reflect the stabilization of ARs.The cellulose/lignin ratio decrease rate for AR1(18.3%)was much higher than that for AR13(3.1%),while the corresponding humic-acid/fulvic-acid ratio increased from 1.44 to 2.16.The dominant bacteria shifted from Corynebacterium(9.2%),Acinetobacter(6.6%),and Fermentimonas(6.5%),genes related to the decompose of biodegradable organics,to Stenotrophomonas(10.2%)and Clostridiales(3.7%),which were associated with humification.The aeration efficiencies of lab-scale tests were in the range of 5.4–11.8 g BDM/L O_(2)for ARs with disposal ages of 1–13 years,and in situ landfill reclamation,ARs with disposal ages of 10–18 years were around 1.9–8.8 g BDM/L O_(2),as the disposal age decreased.The increased discrepancy was observed in ARs at the lab-scale and field scale,indicating that the forced aeration rate should be adjusted based on ARs and the unit compartment combined,to reduce the operation cost.

Optimizing the aeration performance of a perforated pooled circular stepped cascade aerator using hybrid ANN-PSO technique

Artificial aeration system for aquaculture ponds becomes essential to meet the oxygen requirement posed by the aquatic species.The performance of an aerator is generally mea-sured in terms of standard aeration efficiency(SAE),which is significantly affected by the different geometric and dynamic parameters of the aerator.Therefore,to enhance the aer-ation performance of an aerator,these parameters need to be optimized.In the present study,a perforated pooled circular stepped cascade(PPCSC)aerator was developed,and the geometric and dynamic parameters of the developed aerator were optimized using the hybrid ANN-PSO technique for maximizing its aeration efficiency.The geometric parameters include consecutive step width ratio(W_(i-1)/W_(i))and the perforation diameter to the bottom-most radius ratio(d/R_(b)),whereas the dynamic parameter includes the water flow rate(Q).A 3–6-1 ANN model coupled with particle swarm optimization(PSO)approach was used to obtain the optimum values of geometric and dynamic parameters correspond-ing to the maximum SAE.The optimal values of the consecutive step width ratio(W_(i-1)/W_(i)),the perforation diameter to the bottom-most radius ratio(d/R_(b)),and the water flow rate(Q)for maximizing the SAE were found to be 1.15,0.0027 and 0.0167 m^(3)/s,respectively.The cross-validation results showed a deviation of 3.07%between the predicted and experimen-tal SAE values,thus confirming the adequacy of the proposed hybrid ANN-PSO technique.

Treatment of Slightly Polluted Wastewater in an Oil Refinery Using a Biological Aerated Filter Process

The slightly polluted wastewater from oil refinery contains some COD, oil pollutants and suspended solids （SS）. A small-scale fixed film biological aerated filter （BAF） process was used to treat the wastewater. The influences of hydraulic retention time （HRT）, air/water volume flow ratio and backwashing cycle on treatment efficiencies were investigated. The wastewater was treated by the BAF process under optimal conditions： the HRT of 1.0 h, the air/water volume flow ratio of about 5 ： 1 and the backwashing cycle of every 4-7 days. The results showed that the average removal efficiency of COD, oil pollutants and SS was 84.5%, 94.0% and 83.4%, respectively. And the average effluent concentration of COD, oil pollutants and SS was 12.5, 0.27, 14.5 mg·L^-1, respectively. The experimental results demonstrated that the BAF process is a suitable and highly efficient method to treat the wastewater.

Treatment performance of integrated biological aerated filter by orthogonal experiments

Biological aerated filters have many advantages such as small volume and high treatment efficiency. This research focused on sewage treatment performance of integrated biological aerated filter (IBAF) under different conditions such as aeration, hydraulic retention time and the height of fillers layer, to identify the turn of marked affecting factor of removal performance through orthogonal experiments, optimize the function parameter of IBAF, reveal the regularity of sewage treatment of IBAF under different conditions, and adopt suitable measures to guarantee excess water quality of IBAF.

加气对南疆设施无花果生长及土壤磷吸收转化的影响

以‘布兰瑞克’无花果果树为试验材料,采用地下穴贮灌溉装置对无花果根际土壤通气,设置加气施磷肥(OP)、加气不施磷肥(OF)、不加气施磷肥(NP)、不加气不施磷肥(NF)4个处理,研究其对南疆设施无花果植株的生长情况及土壤磷吸收转化的影响,以期为地下穴贮滴灌注气技术在设施无花果中的应用提供参考依据。结果表明:OP、OF、NP在不同程度上均可以促进无花果植株生长,增加各土层土壤的含水量及调节土壤pH。其中OP在30~80 d、OF在50~80 d均显著促进无花果的新梢生长;在0~20 cm土层中,OP、OF、NP的土壤含水量较NF分别降低15.02%、9.84%、1.98%;OP较NF处理能够显著提高各土层的土壤酸性磷酸酶活性,其中对0~20 cm土层提升效果最佳,提高了157.37%;OP处理的土壤速效磷含量在0~20、20~40、40~60 cm的3个土层中分别提高了212.82%、160.79%、98.77%。综上,加气处理对‘布兰瑞克’无花果植株的生长及土壤全磷转换为速效磷等均有促进作用。

夏冬两季AAO工艺微孔曝气系统性能测定与评价

以上海某城镇污水处理厂为研究对象,在夏冬两季通过好氧池沿程实地测试,对污染物去除效果和曝气系统性能进行系统测定与评价。结果表明,冬季水量负荷较夏季低,好氧池反应时间延长且充分曝气,抵消了低温对硝化的负面影响,因此,夏冬两季出水水质均达到《城镇污水处理厂污染物排放标准》(GB 18918—2002)一级A排放标准。与夏季相比,冬季生物处理工艺的需氧量更高,微孔曝气系统的氧传质效率更低,导致所需供气量更高,曝气效率更低。夏季和冬季供氧量比需氧量分别高38.99%和7.07%,夏季节能潜力较大。好氧池污染物浓度沿程下降,末端污染物浓度几乎不变,而末端溶解氧浓度远高于前端,说明末端的供氧并未用于COD_(Cr)氧化和氨氧化作用,存在过度曝气现象,因此,可适当降低好氧池末端供气量。

陶瓷膜臭氧曝气强化传质工艺优化研究

臭氧氧化技术存在气液传质效率低、臭氧利用率不高等问题,改进臭氧的曝气条件是强化臭氧传质效率的重要方法。进行了陶瓷膜臭氧曝气的试验研究,表征了陶瓷膜的微孔性与形态结构,探究了不同操作条件对臭氧传质效率的影响。结果表明:臭氧传质系数随进气流量、气相臭氧质量浓度的增加先增大后减小,最佳条件:进气流量为0.4 L/min,气相臭氧质量浓度为28 mg/L。陶瓷膜表面疏水改性可以提升臭氧传质效率,臭氧溶解度及传质效率随膜孔径的减小而增大,随着曝气压力从0.1 MPa提高到0.5 MPa,臭氧传质效率先增大后减小,最佳的曝气压力约为0.3 MPa,并基于杨氏方程分析了陶瓷膜加压曝气强化臭氧传质的机理。

加气对西北旱区膜下滴灌棉花光合及水分利用效率的影响

为探明西北旱区滴灌棉花适宜的加气灌溉模式,试验以不加气灌溉为对照(CK),设置5个加气灌溉处理:苗期加气(AS)、蕾期加气(AB)、花铃期加气(AF)、蕾期加气+花铃期加气(ABF)、苗期加气+蕾期加气+花铃期加气(AW);研究了不同生育期加气灌溉对西北旱区棉花光合作用及水分利用效率的影响.结果表明,与CK相比,所有加气处理的光合特性及地上部生物量都显著提高,其中处理AW较CK的净光合速率显著增加22.68%,蒸腾速率显著增加41.19%,气孔导度显著增加33.42%,胞间CO 2浓度显著降低16.22%;花铃期加气灌溉使西北旱区棉花地上部茎、叶、蕾/铃干物质累积量分别显著增加29.26%,11.15%和33.41%.不同生育期加气灌溉下,棉花光合特性、地上部生物量以及产量最优的处理为AW和AF,且差异不具有统计学意义;但是处理AF的水分利用效率最高,为1.51 kg/m 3,显著高于处理AW.因此,从高效节水增产的角度考虑,在棉花花铃期进行加气(AF)可作为西北旱区膜下滴灌棉花的最佳加气灌溉模式.

初期雨水就地调蓄处理工程方案及运行策略

雨水排口出流污染是南方某市“两湖”水质恶化的重要因素之一,通过排水管网改造解决雨污混接污染问题,采用调蓄处理的工程方案解决初期雨水污染及溢流污染问题,初期雨水处理工艺采用“高效沉淀池+曝气生物滤池(BAF)+高效澄清池+转盘滤池”的组合工艺。通过中试试验验证BAF间歇运行的适用性,连续运行工况下,COD_(Cr)、氨氮均能稳定达到Ⅳ类水水质;当间歇运行时,随着间歇期增大,氨氮的去除效果大幅度降低,当间歇期超过4 d后,出水氨氮浓度无法达到地表Ⅳ类水水质。文章提出了初期雨水处理工艺运行维护模式,为类似工程提供借鉴。

复合生物膜微生物修复河道水环境技术

由于人口增长和经济建设的扩大,水生态环境系统遭到严重破坏,沿河农村和工矿企业对河道水体的影响尤为严重。作为衡量水体污染程度的重要指标之一,水体中的氨氮和有机污染物对生态环境和人类身心健康造成一定影响,环境治理和水生态系统修复治理迫在眉睫。加之沿河工矿企业生产废水流入河道内,导致河道水体的污染具有多重性和复杂性。根据山西省阳泉市郊区温河治理水质提升工程为例,通过“高效生态浮岛+复合曝气生物膜修复”多方位立体式水生态净化技术和新型绿色生物膜修复技术,最终净化塘出水氨氮≤1.1mg/L,总氮≤1.3mg/L,水质指标达到地表Ⅳ类标准。运行成本0.12元/m^(3),低于同类型最新技术“底泥生物氧化技术”运行成本的3~4倍,值得应用推广。

炼化污水总排水质提标升级改造技术总结

结合炼化企业污水处理场实际运行工况及存在问题,论述了污水总排水质提标升级主要改造内容,重点介绍了高效低氧一体化生物处理、臭氧催化氧化、多级曝气生物滤池、微砂加碳高效沉淀池深度污水处理技术特点。工业应用结果表明,该组合技术先进可靠,去除污水COD、氨氮、总磷效率高,总排污水平均COD 10.92 mg/L,BOD 2.9 mg/L,氨氮0.14 mg/L,总氮6.62 mg/L,总磷0.13 mg/L,石油类0.83 mg/L,完全达到《陕西省黄河流域污水综合排放标准》(DB 61/224—2018)要求,环保效益明显,每年减排COD 3309.4 kg,氨氮4142.4 kg,悬浮物57.6 kg,对改善周边生态环境发挥了积极作用,在国内炼化企业废水综合治理方面具有一定的借鉴价值。

一种改良AO技术在污水处理工程中的应用研究

通过对武汉市经开区一处雨污合流排水明渠污染治理工程的实践,重点展示了一种改良AO技术应用于污水处理工程,该技术理念基于“生物倍增”原理,具有:①大流量低能耗循环回流,气提混合液回流,回流比达到(1∶10)~(1∶100);②超高氧传质效率,6 m清水测试氧传质效率高达50%;③高污泥浓度,运行工况达到6~8 g/L;④低溶氧环境运行,实现0.3~0.5 mg/L,使硝化速率与反硝化速率同时达到一个极高水平。对比其他工艺,优点突出表现在:工艺流程短、布局紧凑、处理效率高、能耗低、管理和维护方便等。

强化供氧条件下潜流型人工湿地运行特性

针对潜流型人工湿地中溶解氧浓度和脱氮率偏低的问题，试验研究了强化供氧对植物和微生物的影响及人工湿地内溶解氧浓度、净化效率的变化规律．结果表明，强化供氧宜在湿地前端进行，最佳气水比为6左右，可采用连续供氧方式．供氧对湿地植物生理特性无明显不良影响，可显著增加湿地中硝化菌、反硝化菌数量，硝化菌可比供氧前高出1—2个数量级，反硝化菌高出1个数量级．强化供氧有效改善了湿地内氧环境，供氧前湿地内溶氧浓度普遍低于0．6mg／L，供氧后氧浓度上升至1mg／L以上．强化供氧有利于各类污染物质尤其是有机物和氮类物质的去除，有机物去除率比原湿地高出10％左右，TN去除率能够达到60％以上．因此，强化充氧措施具有较好的研究和应用价值．

曝气生物滤池去除污染物的机理研究

曝气生物滤池具有体积小、处理效率高、出水水质好、流程简单的优点，最大特点是使用了一种新型粒状填料．它的去除机理主要有过滤、吸附和生物代谢．填料高度对去除效果有很大影响．研究结果表明，去除率同填料高度成正相关，最上层的３７ｃｍ 厚滤料去除污染物的效果最好，该处的ＳＳ、ＣＯＤ、ＢＯＤ５、ＮＨ３Ｎ和ＴＮ的去除率分别为７０％ 、８２５％ 、６６９５％ 、５３６％ 和５０２％ ．

两种曝气设备的清水曝气充氧实验研究

根据清水充氧实验计算,比较了微孔雾化软管曝气和射流曝气的充氧动力效率和氧利用率。以及后续实验的结果,最终得出微孔曝气软管曝气是高效节能的河流整治方法。

加气滴灌提高大棚甜瓜品质及灌溉水分利用效率

为揭示加气频率和滴灌带埋深等对甜瓜产量、品质及水分利用效率的影响,以甜瓜(陕甜一号)为研究对象,采用追加正交试验设计,研究不同加气频率、地下滴灌带埋深及灌水控制上限对大棚甜瓜果实形态、产量、品质及灌溉水分利用效率的影响。结果表明:对果实形态、品质及产量影响的大小顺序依次为加气频率、滴灌带埋深和灌水控制上限。对水分利用效率的影响大小顺序依次为灌水控制上限、加气频率和滴灌带埋深。根区加气能够显著改善果实产量及品质,滴灌带埋深为25 cm,每天加气1次品质及果实形态指标最好,产量最高。灌水量控制在田间持水量的80%时,果实可溶性固形物含量最高,但灌水量为70%田间持水量时,可溶性总糖、产量、水分利用效率最高。综合考虑,最优处理组合为滴灌带埋深25 cm,每天通气一次,灌水控制上限为70%田间持水量。

水-空气引射式冰下深水增氧机的设计与性能试验研究

根据水 -空气引射原理设计了一种新型增氧机 ,可同时进行冰下和深水的增氧 ,以解决我国北方地区冬季鱼类供氧和鱼池水质净化问题。对其主要结构参数进行了设计计算和试验研究。结果显示 ,当喷嘴直径 dp1 =2 5 m m、混合室直径 d3=48m m、截面积比 f3/fp1 =3 .69时 ,该装置的进气量最大 ,增氧动力效率最高 ;进气量与增氧动力效率之间呈正相关关系 ;增氧动力效率随深度的增加而提高 ,增加率为 0 .49kg O2 · m- 1 ;喷嘴位置对动力效率和进气量并无影响。

微孔曝气式增氧机的性能及应用效果

为研究微孔曝气增氧机的增氧性能和池塘应用效果,按照标准规定的方法进行了增氧性能的试验和不同水深对增氧性能影响的试验,并在池塘中进行应用效果的试验。结果显示:微孔曝气式增氧机具有比叶轮式增氧机等增氧机更强的增氧能力,但不同配置的机型,增氧能力随配套功率和曝气管长度的增加而增强,动力效率则呈明显下降趋势;增加曝气管布置深度可以提高增氧性能,安装深度从2 m增加到4 m,增氧能力增加285%,动力效率增加207%,与其它养殖池塘机械增氧设备相比,池塘水体越深,微孔曝气式增气机的增氧优势越明显。目前,池塘采用微孔曝气式增氧机的配置方式不具优势,需要改进提升。

基于Zigbee通信的节能型混合式机械增氧系统

构建了一套增氧系统,采用耕水机和微孔曝气增氧机混合增氧的模式,白天通过定时控制以耕水机工作为主,晚上或阴雨天缺氧时以微孔曝气增氧为主。在环境参数不断变化的情况下,为了保持溶解氧的稳定,控制方法采用误差反传的模糊神经网络控制。试验表明,在相同条件下采用混合式增氧控制较传统的叶轮式增氧可节约电能40.6%,提高产量31.9%,最终利润提高136.1%。水质参数测量采用Zigbee通信,通信协议采用优化的低能量自适应分层协议,并根据水体溶解氧测量的实际要求,设置参数测量的软、硬阈值以减少节点数据发送的次数,达到节能和供电电池剩余能量均衡的目的,试验表明优化后的无线传感网络寿命延长了58%。