Embedded nanoFeCu for sewage treatment: Laboratory-scale and pilot studies

Bimetallic nanoparticles have been widely studied for wastewater treatment, but the study of nanoFeCu for sewage treatment is minimal. In the previous work, ammonia was removed by nanoFeCu via an oxidation reaction, and nitrogen gas was released. However, the performance and reusability of nanoFeCu in treating industrial wastewater have not been reported elsewhere. This study revealed the performance of nanoFeCu for sewage treatment on both laboratory-scale and pilot-scale for the first time. A varied mass of embedded nanoFeCu (eFeCu4) was exposed to sewage water, and the quality of the effluent was measured in terms of ammonia, biological oxygen demand (BOD), and chemical oxygen demand (COD) removal. Fe²⁺ and Cu²⁺ concentrations were measured to determine the stability of eFeCu4 in nine reuse cycles. Results showed that the laboratory-scale experiment removed 20%–30% ammonia from sewage. A similar removal rate was reported in all nine cycles of reuse, which confirmed the usability and reliability of eFeCu4. In the pilot-scale study, ammonia was removed from ~22.3 to ~4.8 mg/L, while BOD and COD were reduced from ~204 to ~56 mg/L and ~71 to ~39.7 mg/L, respectively. The treated effluent quality complies with the effluent discharge standard of Malaysia, and it is also comparable with the effluent quality at sewage treatment plants in Malaysia and overseas. In conclusion, nanoFeCu could be an alternative method for sewage treatment due to its stability and pollutant removal performance. A sustainability and cost-effectiveness study should be conducted to determine the feasibility of a full-scale application.     

Comparative study of nitrification performances of immobilized cell fluidized bed reactor and contact oxidation biofilm reactor in treating high strength ammonia wastewater

BACKGROUND: The immobilized cell fluidized bed reactor and contact oxidation biofilm reactor are two common choices for high strength ammonia wastewater treatment, however, comparative study of the nitrification performance of the two reactors has not been thoroughly studied. The nitrification performance of the two bioreactors when treating strong synthetic ammonia wastewater was investigated and compared. RESULTS: Results demonstrated that the immobilized cell fluidized bed reactor had a shorter acclimation period, and possessed several advantages over the contact oxidation biofilm reactor, in the form of complete oxidation of 150–360 mg L^?1 ammonia wastewater in a shorter time, higher ammonia removal rates (from 9.6 to 4.32 × 10² mgN L^?1 d^?1) over the temperature range 8 to 32 °C, irrespective of organic load. In contrast, a large reduction in ammonia removal was found in the contact oxidation biofilm reactor with chemical oxygen demand (COD) load. The immobilized cell fluidized bed reactor exhibited stable and high rates of nitrification in the long term. CONCLUSION: These facts demonstrated that the immobilized cell fluidized bed reactor is a suitable selection for high strength ammonia wastewater treatment. Copyright © 2007 Society of Chemical Industry     

限氧条件下亚硝化的稳定运行及动力学

采用高氨氮人工配水和序批式反应器,在限氧(0.2～0.3mg/L)条件下,研究了进水氨氮负荷、游离氨和游离亚硝酸对氨氮转化率、亚硝化率和亚硝氮生成速率的影响及游离氨对氨氧化菌的基质抑制动力学。结果表明,在进水氨氮负荷逐步提升过程中,由于高浓度游离氨的抑制作用及负荷冲击的影响,亚硝化效果易出现波动,且负荷越高,亚硝化性能恢复的时间越长。反应系统最终可达到的氨氮容积负荷为3.60kg/(m³·d),亚硝氮生成速率为2.98kg/(m³·d),亚硝化率始终维持在85%左右。反应体系中较高的游离氨浓度(24.4～85.8mg/L)和低浓度溶解氧是维持亚硝化工艺稳定运行的主要因素。游离氨对氨氧化菌的抑制动力学符合Haldane模型,拟合得到最大氨氧化速率为6.71gN/(gVSS·d),游离氨半饱和常数和抑制常数分别为3.2mg/L和27.8mg/L。     

Effects of free ammonia and dissolved oxygen on nitrification and nitrite accumulation in a biofilm airlift reactor

The purpose of this research is to find out the effects of free ammonia concentration and dissolved oxygen on nitrification and nitrite accumulation in a biofilm airlift reactor. Free ammonia seriously inhibited the activity of nitrite oxidizers at the concentration higher than 0.1 mg NH₃-N/L and it was very effective for nitrite accumulation. Dissolved oxygen limitation in the biofilm also caused nitrite accumulation. Long term inhibition decreased the growth rate for nitrite oxidizers, and ammonia oxidizers were the dominant nitrifiers in the wastewater nitrification. Selective accumulation of ammonia oxidizers in the biofilm could be another reason for nitrite accumulation. Free ammonia inhibited nitrite oxidizers immediately, and adaptation to free ammonia was not observed. Therefore, the optimum control of free ammonia and dissolved oxygen concentration is critical for nitrite accumulation and the strategy can be used for selective accumulation of ammonia oxidizers in a bioreactor system.     

复合生物反应器亚硝酸型同步硝化反硝化脱氮

Sequence hybrid biological reactor （SHBR） was proposed, and some key control parameters were investigated for nitrogen removal from wastewater by simultaneous nitrification and denitrification （SND） via nitrite. SND via nitrite was achieved in SHBR by controlling demand oxygen （DO） concentration. There was a programmed decrease of the DO from 2.50 mg·L^-1 to 0.30 mg·L^-1, and the average nitrite accumulation rate （NAR） was increased from 16.5% to 95.5% in 3 weeks. Subsequently, further increase in DO concentration to 1.50 mg·L^-1 did not destroy the partial nitrification to nitrite. The results showed that limited air flow rate to cause oxygen deficiency in the reactor would eventually induce only nitrification to nitrite and not further to nitrate. Nitrogen removal efficiency was increased with the increase in NAR, that is, NAR was increased from 60% to 90%, and total nitrogen removal efficiency was increased from 68% to 85%. The SHBR could tolerate high organic loading rate （OLR）, COD and ammonia-nitrogen removal efficiency were greater than 92% and 93.5%, respectively,, and it even operated under low DO concentration （0.5 mg·L^-1） and maintained high OLR （4.0 kg COD·m^-3·d^-1）. The presence of biofilm positively affected the activated sludge settling capability, and sludge volume index （SVI） of activated sludge in SHBR never hit more than 90 ml·L^-1 throughout the experiments.     

填充床反应器中酶法合成生物蜡酯

研究了填充床式反应器酶法合成生物蜡酯的生产工艺。以大豆油、十六醇为原料,在石油醚体系中,使用实验室自制的固定化Candida sp.99-125为催化剂。对操作参数,如填充高度、进料速度、固定化酶用量、底物摩尔比进行了研究。结果表明,固定化酶质量为47 g,填充高度40 cm（内径3.5 cm）,油醇摩尔比1∶2.4,以4 mL/min速度进料保留时间4 h,产率可达83%。固定化酶在使用16批时,产率仍保持在70%以上。同时,对于填充床的填充方式作了初步探索。     

铬铁酸浸液除铁过程的草酸亚铁回收及铁黑颜料制备

对铬铁酸浸液除铁所得草酸亚铁进行氧气氧化-氨浸处理,回收除铁剂草酸盐并用其制备氧化铁黑颜料. 考察了氨水用量、反应温度、液固比、反应时间、氧气流量、反应液pH值及晶化温度等对C2O42-浸出率和氧化铁黑质量的影响. 结果表明,反应液经60℃晶化处理后,在反应温度80℃、氨水与草酸亚铁摩尔比为3、液固比5 mL/g、氧气流量0.1 L/min、pH值6.9~7.4、反应时间3 h的条件下,C2O42-的浸出接近100%,得到的氧化铁黑质量与国产722氧化铁黑产品相当.     

Removal of ciprofloxacin from aqueous solution by a continuous flow electro-coagulation process

This study deals with the performance and modeling of the electro-coagulation process for ciprofloxacin (CIP) removal by using aluminum electrode as anode in a continuous electrochemical reactor. The initial pH, temperature, current density, time and flow rate were selected as independent variables in response surface methodology (RSM) involving a five-level central composite design (CCD), while CIP removal efficiency was considered as the response function. The result of optimization showed that the maximum amount of CIP removal efficiency (88%) presented at the optimal condition of pH=5.6, t=100min, T=25.5 °C, I=5.6mA/cm² and V=25.9 mL/min. In addition, the mineralization of the CIP was investigated by chemical oxygen demand (COD) and total organic carbon (TOC) measurements that showed 77% COD removal and 49%TOC removal.     

短时絮凝-高速磁沉降溢流污水快速处理装置开发

开发了一种短时絮凝-高速磁沉降反应器,依靠投加磁种和外加磁场来强化絮凝和缩短污泥沉降时间。该反应器具有水力停留时间短、占地面积小、操作灵活等优点。试验证明,对于溢流污水,当水力停留时间为8 min时,且在PAC投加量为30 mg.L-1、磁种投加量为350 mg.L-1、磁场强度为300 mT时,反应器具有最佳运行工况,其对氨氮、总磷、SS和COD去除率分别达到76.67%、85.25%、92.5%、76.22%。     

厌氧氨氧化包埋填料处理稀土尾矿废水的中试脱氮和优化

针对稀土尾矿废水的成分复杂和低化学需氧量(chemical oxygen demand,COD)的水质条件,采用厌氧氨氧化包埋填料进行处理。首先进行了厌氧氨氧化包埋填料的适应和驯化,然后分别探究了厌氧氨氧化包埋填料单独处理稀土尾矿废水和耦合反硝化包埋填料处理稀土尾矿废水的脱氮性能。结果表明,厌氧氨氧化包埋填料对稀土尾矿废水有良好的适应性,采用阶梯式底物和缩短水力停留时间(hydraulic retention time,HRT)的运行策略进行适应和驯化后,总氮去除负荷(nitrogen removal load rate,NRR)最高可达0.99kg N/(m³·d),较适应和驯化前提高了8.39倍。高通量测序结果表明,厌氧氨氧化优势菌属(Candidatus Kuenenia)的相对丰度从5.53%上升至35.67%,实现了有效富集,而适应和驯化前的优势菌属(Candidatus Brocadia)不适应环境被淘汰。面对原水氨氮浓度波动时,厌氧氨氧化包埋填料单独处理稀土尾矿废水的NRR最高可达1.02kg N/(m³·d),出水氨氮的平均浓...     

Protein Recovery from Sweet Potato Starch Wastewater by Foam Separation

In this study, an inclined foam separation column was designed to effectively recover protein from sweet potato starch wastewater. The effects of the influent protein concentration, pH, air flow rate, influent volume, foaming time, and inclined column angle on foam separation performance were assessed. The optimum foam separation conditions consisted of influent protein concentration 4.51 mg/mL, pH 4, air flow rate 0.15 mL/min, influent volume 500 mL, foaming time 100 min, and inclined column angle 30°. In these conditions, protein recovery percentage and enrichment ratios were 84.1% and 1.3, respectively. The biochemical oxygen demand (BOD₅) and chemical oxygen demand (COD_Cr) of the residual solution (620 and 950 mg/mL, respectively) were lower than those of the original (influent) solution.     

还原条件对磷化镍催化剂的HDN性能影响

采用原位还原技术制备出Ni2P/TiO2-Al2O3催化剂,在连续流动固定床高压微反装置中,以喹啉为模型化合物对催化剂的加氢脱氮性能进行评价。考察了原位还原条件及加氢工艺条件对催化剂的加氢脱氮性能的影响。确定了最佳还原条件:氢气流速100 mL/min,还原终温550℃,还原压力1 MPa,还原时间150 min;反应条件为:温度360℃、压力3 MPa、空速3 h-1、氢油比500∶1。最适宜反应条件下喹啉的脱氮率为98%。     

低pH对高负荷厌氧氨氧化反应器性能的影响

厌氧氨氧化(ANAMMOX)工艺是一种新型生物脱氮工艺,具有良好的应用前景。但ANAMMOX以亚硝酸盐为电子受体,需与短程硝化(SHARON)联合应用。SHARON是一个产酸反应,而ANAMMOX是一个嗜碱反应,后者会受前者的干扰。试验结果表明,低进水pH冲击对高负荷(总氮负荷9.3～27.7kg·(m3·d)-1)ANAMMOX反应器效能具有显著影响。在一定范围内,提高总氮负荷可削弱低进水pH冲击的影响,设置回流也可缓解低进水pH冲击所致的负面效应。低进水pH冲击对厌氧氨氧化反应器效能的影响主要来自低pH与游离亚硝酸毒性的双重抑制,其中低pH的直接作用对反应器效能的影响更大。低进水pH冲击所致的反应器效能恶化可采用停车自然恢复、清水冲洗恢复和外加碱液恢复。     

双介质阻挡放电低温等离子体对模拟堆肥气体中氨气的去除

针对固体废物堆肥设施氨气污染问题,本文首次运用双介质阻挡放电低温等离子体（DDBD）技术去除模拟堆肥气体中的氨气。考察了输入功率、氨气流速、氨气初始浓度、反应器放电间隙、氧气含量等参数对氨气去除率和低温等离子体系统能量效率的影响,并分析了副产物的生成情况及其影响因子。研究结果表明,氨气去除率与输入功率和氧气含量呈正相关,与氨气流速和氨气初始浓度呈负相关。低温等离子体系统的能量效率与氨气流速、氨气初始浓度、氧气含量均正相关,但随输入功率的增加先升高后降低。研究发现,在所设定的反应条件下,4mm放电间隙反应器的能耗最低,能量效率最高。O₃和NO_x是DDBD去除氨气的反应副产物,其浓度均与氧气含量呈正相关,均呈现随输入功率的增加先升高后降低的趋势。     

高效气升循环式短程硝化工艺性能

采用模拟含氨废水和气升循环式好氧反应器研究了短程硝化(partial nitrification,PN)工艺的高效性能。试验结果表明,气升式短程硝化工艺具有很高的容积效率,在30℃、进水氨氮浓度358.5～942.3mg·L-1时,反应器水力停留时间可缩至0.86～2.00h,反应器每天周转次数高达12～28次,平均容积去除速率高达5.5kgN·m-3·d-1,处于文献报道的最高水平范围。该工艺具有超常的运行稳定性,在进水基质浓度、进水流量和pH波动的情况下,氨氮去除率、出水氨氮浓度和亚硝氮积累率的相对标准偏差分别为3.1%～16.8%,4.3%～26.5%和0.4%～5.3%。该工艺的高效稳定性可归因于气升循环式反应器的强污泥持留能力和短程硝化污泥的高反应活力。系统内持留的污泥浓度高达4.0～5.2g VSS·L-1,动力学试验测得的最高比污泥活性达到2.71gN·(g VSS)-1·d-1。     

静电纺丝制备苯乙烯马来酸酐共聚物纳米纤维及其固定化b-D-半乳糖苷酶

采用静电纺丝技术制备苯乙烯-马来酸酐共聚物纳米纤维,最佳电纺条件为：聚合物浓度0.35 g/mL、针尖到接收板距离25 cm、电纺液流量250 mL/h、电压21 kV. 该条件下获得了直径约300 nm且分布均一的纳米纤维. 利用该纳米纤维固定b-D-半乳糖苷酶,固定化反应的最适pH值为4.0,此时酶负载量为(15.1±0.5) mg/g. 固定化酶催化2-硝基苯酚-b-D-半乳吡喃糖苷水解反应的米氏常数Km=2.7 mmol/L,略大于游离酶的Km值(2.2 mmol/L);最大反应速率Vmax为97.2 mmol/(min×mg),为游离酶的47.8%. 固定化酶在37℃下重复操作21次后活性损失仅为15%. 在连续搅拌式反应器中将固定化酶用于催化乳糖的水解反应,连续使用17 d仍能稳定运行.     

Autotrophic biological nitrogen removal from saline wastewater under low DO

BACKGROUND: This study was conducted to investigate the feasibility and performance of nitrogen removal through the complete autotrophic nitrogen removal over nitrite (CANON) process for saline wastewater in a continuous reactor, and to characterize microorganisms in the sludge from the reactor using DNA‐based techniques. RESULTS: The nitrogen removal experiment in the reactor was operated over five phases for 286 days treating a synthetic sewage of 1.2% salinity at 21–25 °C. At dissolved oxygen (DO) concentrations of 0.5–1.0 mg L^?1 and in the presence of glucose, NO₂^? was accumulated, indicating the activity of ammonia‐oxidizing bacteria (AOB). At DO concentration of 0.5 mg L^?1 without organic substrate, the anaerobic ammonium oxidation (Anammox) process was the major pathway responsible for nitrogen removal, with a total nitrogen removal of 70% and an ammonium conversion efficiency of 96%. A maximum ammonium removal rate of 0.57 kg‐N m^?3 d^?1 was achieved during the experimental period. The concentrations of AOB and Anammox bacteria were monitored over the operation of reactor using quantitative real‐time polymerase chain reaction (qRT‐PCR). CONCLUSION: In this study, autotrophic nitrogen removal process was achieved under salinity condition in a one‐reactor system. An over 100 fold increase of AOB was found due to the increased supply of ammonium at the beginning, then AOB concentration decreased temporarily in correspondence with the decreased DO, and the AOB resumed their concentration at the last phase. The Anammox bacteria abundance was about 150 fold higher than that at the beginning, indicating the successful enrichment of Anammox bacteria in the reactor. Copyright © 2010 Society of Chemical Industry     

超声波内环流气升式反应器处理印染废水

采用超声波内环流气升式反应器对某印染厂印染废水进行处理研究。考察了反应时间、臭氧流量、超声声强对印染废水的脱色率及COD去除率的影响。结果表明,随着反应时间的增加,脱色率和COD去除率均增大,最佳反应时间为30 min;脱色率及COD去除率随着臭氧流量的增加而增大,最佳流量为200L/h;超声声强最佳值为0.5 W/cm2,此时脱色率及COD去除率分别为74.8%、35.6%。实验证明,对印染废水的脱色率及COD去除率,超声波内环流气升式反应器处理效果大于超声与臭氧单独作用简单之和,脱色率和COD去除率分别提高了23.0%和6.5%。超声波内环流气升式反应器结合了超声波的声化学作用及内环流气升式反应器供气效率高的特点,发挥了超声波与内环流气升式反应器的协同效应。     

Treatment of domestic wastewater by subsurface flow constructed wetlands in Jordan

The use of subsurface flow constructed wetlands for treating domestic wastewater in Jordan is described. The objective was to study the performance of subsurface flow constructed wetlands as a low-cost technology for treating domestic wastewater. Results show that subsurface flow constructed wetlands are capable of reducing biochemical oxygen demand (BOD), different forms of nitrogen, total suspended solids (TSS), fecal coliform count (FCC), and total coliform count (TCC). However, removal efficiencies differ from bed to bed and from month to month. Results show that there is strong correlation between BOD₅ removal efficiency and BOD₅ loading in kg/ha, which is defined as BOD₅ loading rate in kg/ha.d multiplied by residence time. The coefficient of determination (R²) for the six beds varied from 0.827 for bed number one to 0.608 for bed number four. Total nitrogen, ammonia nitrogen, and nitrate nitrogen reductions were observed, which suggestthat, nitrification as well as denitrificationtookplace in the beds. TSS reduction was observed in all beds. However, removal efficiency differed from bed to bed and for the same bed from month to month. Total and fecal coliform counts were reduced by one to three logs, because influent was high in total and fecal coliform counts were still high.