An innovative integrated oxidation ditch with vertical circle(IODVC) for wastewater treatment

The oxidation ditch process is economic and efficient for wastewater treatment, but its application is limited in case where land is costly due to its large land area required. An innovative integrated oxidation ditch with vertical circle(IODVC) system was developed to treat domestic and industrial wastewater aiming to save land area. The new system consists of a single channel divided into two ditches(the top one and the bottom one by a plate), a brush, and an innovative integral clarifier. Different from the horizontal circle of the conventional oxidation ditch, the flow of IODVC system recycles from the top zone to the bottom zone in the vertical circle as the brush is running, and then the IODVC saved land area required by about 50% compared with a conventional oxidation ditch with an intrachannel clarifier. The innovative integral clarifier is effective for separation of liquid and solids, and is preferably positioned at the opposite end of the brush in the ditch. It does not affect the hydrodynamic characteristics of the mixed liquor in the ditch, and the sludge can automatically return to the down ditch without any pump. In this study, experiments of domestic and dye wastewater treatment were carried out in bench scale and in full scale, respectively. Results clearly showed that the IODVC efficiently removed pollutants in the wastewaters, i.e., the average of COD removals for domestic and dye wastewater treatment were 95% and 90%, respectively, and that the IODVC process may provide a cost effective way for full scale dye wastewater treatment.

Enhanced biological nutrients removal using an integrated oxidation ditch with vertical circle from wastewater by adding an anaerobic column

Compared to conventional oxidation ditches, an integrated oxidation ditch with vertical circle （IODVC） has the characters of concise configuration, simple operation and maintenance, land saving and automatical sludge returning. By the utilization of vertical circulation, an aerobic zone and an anoxic zone can be unaffectedly formed in the IODVC. Therefore, COD and nitrogen can be efficiently removed. However, the removal efficiency of phosphorus was low in the IODVC. In the experiment described, a laboratory scale system to add an anaerobic column to the IODVC has been tested to investigate the removal of phosphorus from wastewater. The experimental results showed that the removal efficiency of TP with the anaerobic column was increased to 54.0% from 22.3% without the anaerobic column. After the acetic sodium was added into the influent as carbon sources, the mean TP removal efficency of 77. 5 % was obtained. At the same time, the mean removal efficiencies of COD, TN and NH3-N were 92.2%, 81.6% and 98.1%, respectively, at 12 h of HRT and 21-25 d of SRT. The optimal operational conditions in this study were as follows： recycle rate = 1.5-2.0, COD/TN 〉 6, COD/TP 〉 40, COD loading rate = 0.26-0.32 kgCOD/（kgSS· d）, TN loading rate = 0. 028-0. 034 kgTN/（ kgSS·d） and TP loading rate = 0.003-0.005 kgTP/（kgSS· d）, respectively.

Addition of anaerobic tanks to an oxidation ditch system to enhance removal of phosphorus from wastewater

The oxidation ditch has been used for many years all over the world as an economic and efficient wastewater treatment technology. It can remove COD, nitrogen and a part of phosphorus efficiently. In the experiment described, a pilot scale Pasveer oxidation ditch system has been tested to investigate the removal of phosphorus from wastewater. The experimental results showed that influent total phosphorus(TP) was removed for 35%-50%. After this, two anaerobic tanks with total volume of 11 m 3 were added to the system to release phosphorus. As a result, the TP removal efficiency increased by about 20%. At an anaerobic HRT of about 6 hours, a TP removal efficiency of 71% was achieved.

Flow characteristic and wastewater treatment performance of a pilot-scale airlift oxidation ditch

A pilot-scale airlift oxidation ditch using bubble diffuser and baffle as aerator was operated in a wastewater treatment plant(WWTP)to investigate its flow characteristic and wastewater treatment performance.Compared with the conventional oxidation ditch process,effective depth and oxygen utilization efficiency of this new process was improved by underwater aeration.Furthermore,it had a reversed velocity distribution,which decreased from the bottom to the top on vertical section.Velocity measurement showed that a velocity over 0.2 m/s at the bottom was sufficient to prevent sludge settlement during long term operation.Application of these concepts would save land area and energy consumption by about 25%–50%and 55%,respectively.In this new system,organic biodegradation and nitrification could be well achieved.Denitrification could occur steadily in the straight part by adjusting the airflow rate.An average TN removal rate of 63%was achieved with dissolved oxygen(DO)concentrations between 0.6 mg/L and 1.5 mg/L.The main pollutants in the effluent could meet the strictest discharge standard(COD<50 mg/L,NH4_(+)^(–)N<5 mg/L,and TN<15 mg/L)in China now.

Removal of airborne microorganisms emitted from a wastewater treatment oxidation ditch by adsorption on activated carbon

Bioaerosol emissions from wastewater and wastewater treatment processes are a significant subgroup of atmospheric aerosols. Most previous work has focused on the evaluation of their biological risks. In this study, however, the adsorption method was applied to reduce airborne microorganisms generated from a pilot scale wastewater treatment facility with oxidation ditch. Results showed adsorption on granule activated carbon （GAC） was an efficient method for the purification of airborne microorganisms. The GAC itself had a maximum adsorption capacity of 2217 CFU/g for airborne bacteria and 225 CFU/g for fungi with a flow rate of 1.50 m^3/hr. Over 85% of airborne bacteria and fungi emitted from the oxidation ditch were adsorbed within 80 hr of continuous operation mode. Most of them had a particle size of 0.65-4.7 μm. Those airborne microorganisms with small particle size were apt to be adsorbed. The SEM/EDAX, BET and Boehm＇s titration methods were applied to analyse the physicochemical characteristics of the GAC. Relationships between GAC surface characteristics and its adsorption performance demonstrated that porous structure, large surface area, and hydrophobicity rendered GAC an effective absorber of airborne microorganisms. Two regenerate methods, ultraviolet irradiation and high pressure vapor, were compared for the regeneration of used activated carbon. High pressure vapor was an effective technique as it totally destroyed the microorganisms adhered to the activated carbon. Microscopic observation was also carried out to investigate original and used adsorbents.

Anoxic phosphorus removal in a pilot scale anaerobic-anoxic oxidation ditch process

The anaerobic-anoxic oxidation ditch(A^(2)/O OD)process is popularly used to eliminate nutrients from domestic wastewater.In order to identify the existence of denitrifying phosphorus removing bacteria(DPB),evaluate the contribution of DPB to biological nutrient removal,and enhance the denitrifying phosphorus removal in the A^(2)/O OD process,a pilot-scale A^(2)/O OD plant(375 L)was conducted.At the same time batch tests using sequence batch reactors(12 L and 4 L)were operated to reveal the significance of anoxic phosphorus removal.The results indicated that:The average removal efficiency of COD,NH^(+)_(4),PO^(3–)_(4),and TN were 88.2%,92.6%,87.8%,and 73.1%,respectively,when the steady state of the pilotscale A^(2)/O OD plant was reached during 31–73 d,demonstrating a good denitrifying phosphorus removal performance.Phosphorus uptake took place in the anoxic zone by poly-phosphorus accumulating organisms NO^(-)_(2) could be used as electron receptors in denitrifying phosphorus removal,and the phosphorus uptake rate with NO^(-)_(2) as the electron receptor was higher than that with NO^(–)_(3) when the initial concentration of either NO^(-)_(2) or NO^(–)_(3) was 40 mg/L.

Degradation analysis of A^2/O combined with AgNO3 + K2FeO4 on coking wastewater

In this work, a coking wastewater was selected and a biochemical Az/O treatment device for fractional degradation was designed and employed. After each stage of the treatment, the products were analyzed through gas chromatography-mass spectroscopy （GC-MS） to determine their composition. Finally, AgNO3 ＋ K2FeO4 was used as an advanced deep catalytic oxidation treatment. It was concluded from the analysis that cyclic organics could be degraded and the chemical oxygen demand （COD） was controlled within 50 mg. L-1, in line with the target value, Meanwhile, the spectra obtained from the GC-MS were in accordance with the conclusions reached based on the COD. The research results showed that all hard-degradable organics in coking wastewater could be eliminated through the A2/O bio-membrane treatment and the advanced treatment of making use of K2FeO4 as an oxidant and Ag＋ as a catalyst, the catalytic efficiency with Ag＋ as a catalyst of K2FeO4 was very high. Ag＋ could evidently improve the oxidation capacity of K2FeO4 to wastewater in its short stability time, and this is an important innovation.

Reduction and characterization of bioaerosols in a wastewater treatment station via ventilation

Bioaerosols from wastewater treatment processes are a significant subgroup of atmospheric aerosols. In the present study,airborne microorganisms generated from a wastewater treatment station（WWTS） that uses an oxidation ditch process were diminished by ventilation.Conventional sampling and detection methods combined with cloning/sequencing techniques were applied to determine the groups,concentrations,size distributions,and species diversity of airborne microorganisms before and after ventilation. There were 3021 ± 537 CFU/m3 of airborne bacteria and 926 ± 132 CFU/m3 of airborne fungi present in the WWTS bioaerosol.Results showed that the ventilation reduced airborne microorganisms significantly compared to the air in the WWTS. Over 60% of airborne bacteria and airborne fungi could be reduced after4 hr of air exchange. The highest removal（92.1% for airborne bacteria and 89.1% for fungi） was achieved for 0.65–1.1 μm sized particles. The bioaerosol particles over 4.7 μm were also reduced effectively. Large particles tended to be lost by gravitational settling and small particles were generally carried away,which led to the relatively easy reduction of bioaerosol particles0.65–1.1 μm and over 4.7 μm in size. An obvious variation occurred in the structure of the bacterial communities when ventilation was applied to control the airborne microorganisms in enclosed spaces.

生物组合工艺处理石油化工废水工程实例

随着石油化工工业的发展和环保要求的提高,石油化工废水处理受到广泛关注。以河南某石油化工有限公司生产废水为研究对象,通过预处理、厌氧-好氧-缺氧-好氧(AOAO)、曝气生物滤池(BAF)、臭氧组合工艺进行处理,结果表明,整个工艺运行稳定,各工艺段都能保持较高的COD去除率,预处理、AOAO、BAF平均去除率分别约为75%、90.2%、91.3%,经臭氧处理后出水平均COD约为63 mg/L,COD排放满足《污水综合排放标准》(GB 8978-1996)中的石油化工工业二级标准。NH_(4)^(+)-N去除率约87.7%,出水平均浓度约为9 mg/L,满足GB 8978-1996石油化工工业一级标准。

某低碳氮比污水处理厂MBBR氧化沟+深度处理工程案例

西北黄土塬地区某污水处理厂处理规模2×10^(4) m^(3)/d,采用改良型氧化沟工艺,提标改造工程建成后出水水质由《城镇污水处理厂污染物排放标准》(GB 18918-2002)一级B提高至一级A标准。针对原水低碳氮比、高悬浮物水质特性,提标改造工程采用强化生物脱氮除磷处理和增加深度处理流程的措施,即采用MBBR氧化沟+高效沉淀池+反硝化深床滤池+次氯酸钠消毒工艺,实际运行中各项出水水质指标达到或优于一级A排放标准。污水处理单位运营成本及总成本分别为1.40、2.73元/m^(3)。

氧化沟同时硝化反硝化的生物脱氮机理

氧化沟是一种得到广泛应用的有机废水生物反应器 ,简要介绍了氧化沟生物废水处理技术的特点和典型工艺 ,并就氧化沟的硝化反硝化脱氮功能和同时硝化反硝化进行了讨论 ,运用电子计量学方法 ,推导并讨论了同时硝化反硝化反应的计量方程式。

奥贝尔氧化沟的工程应用性能研究

通过对奥贝尔氧化沟工程实际运行工况的测试，分析研究了脱氮功能、抗冲击负荷能力、去除难降解有机物能力以及污泥性能等特征，并就其三沟ＤＯ呈０－１－２的梯度分布与氮的去除机理进行了探讨。

焦化废水深度处理技术综述

焦化废水是煤焦化过程产生的废水,含有高浓度的酚类、苯系物、杂环化合物、多环化合物等有机污染物,并且高盐、高氨氮,是一类难处理的工业废水。随着国家对焦化废水的管理日趋严格,传统的"预处理+生化处理"工艺很难满足排放或回用要求,因此对焦化废水的深度处理势在必行。从物化法和生化法两个方面对目前焦化废水深度处理常用技术的研究和应用情况进行了介绍,并探索性地提出了焦化废水深度处理技术未来的研究和发展方向。

A^2/O氧化沟工艺中NO3^-对生物除磷影响

为研究NO3^-对生物除磷的影响,采用A^2/O氧化沟中试对城市污水进行4个月的研究,并结合静态试验和实际A^2/O氧化沟污水处理厂运行结果,研究NO3^-对厌氧释磷影响,首次全面研究NO3^-对二沉池释磷的影响.中试试验反应器总有效容积为375 L.结果表明,氧化沟出水ρ（NO3^-）〉5.0 mg/L时,回流污泥带入的NO3^-较多,不利于磷的释放,TP去除率随出水NO3^-的升高而降低;氧化沟出水ρ（NO3^-）〈5.0 mg/L时,NO3^-较低导致在二沉池中进行了内碳源释磷反应,TP去除率随NO3^-的降低而降低;静态试验结果证明当ρ（NO3^-）〉0.5 mg/L时,NO3^-抑制磷的内碳源释放.NO3^-降低至0.5 mg/L以下时,发生内碳源释磷,比内碳源释磷速率为0.18-0.47 mg/（gVSS.h）;某污水处理厂运行结果也证明,二沉池污泥停留时间过长,发生内碳源释磷致使出水TP升高.

高级氧化—生化组合工艺处理难降解有机废水的研究进展

综述了近五年来(2004～2008年)高级氧化与生化组合工艺处理难降解有机废水的研究进展,提出了根据废水水质对高级氧化与生物处理技术进行合理组合的原则,同时还介绍了用高级氧化-生化组合工艺处理难降解有机废水的工程实例。

氧化塘工艺处理规模化养猪场污水

采用固液分离太阳能折流式厌氧塘/兼氧塘/强化好氧塘工艺处理养猪场污水,处理出水水质(COD≤400 mg/L、NH3-N≤70 mg/L)达到《畜禽养殖业污染物排放标准》(GB 18596—2001),运行成本为0.34元/m3,净运行成本为0.27元/m3。

氧化沟污水处理新技术

简述了氧化沟的发展过程 ,重点介绍了国外两种新型的工艺———三槽式氧化沟和船形沟内澄清池氧化沟的基本结构、工艺特点等 ,以供设计选用参考 ,并讨论了我国的生物膜氧化沟 。

氧化沟中试装置低温条件下脱氮除磷效果分析

以实际污水处理厂沉砂池出水为研究对象,检测分析了低温运行条件下微孔曝气氧化沟中试装置脱氮除磷效果随温度的变化情况。结果表明,水温低于11℃时,试验装置的脱氮除磷效果明显变差,并分析了硝化和反硝化效率不高的原因,提出了相应的运行调整措施与建议,其结论对同类型污水处理厂的运行管理有参考价值。

用ORP作为氧化沟同步硝化反硝化控制参数

同步硝化反硝化（simultaneous nitrification and denitrification，简称SND）是氧化沟工艺实现优良脱氮效果的主要原因，为了较好实现SND，采用ORP作为氧化沟工艺SND的控制参数．采用缺氧-厌氧-氧化沟模型对市政污水进行了生物脱氮研究．UORP在-30～30mV，NH4^＋和NO3^-的含量均比较低，发生了较好的SND；UORP在30mV以上，出水的总无机氮（TIN）中95％以上为NO3^-，该状况下硝化效果良好，UORP在-30mV以下，硝化不充分，出水的TIN中78％以上为NH4^＋；UORP在-30～30mV，TN的去除率在88％以上，SND作用去除的NO3^-占总的NO3^-去除的99％以上；氧化沟中的NH4^＋和NO3^-之比的对数与UORP有着很好的相关性，相关系数R=-0．97．

植物-生物膜氧化沟处理生活污水的中试研究

植物-生物膜氧化沟系统将多种污水处理工艺包含在极其简单的装置中,兼具氧化沟、生物膜法和植物修复三种处理过程。采用该工艺处理生活污水的试验结果表明,对COD、TN、TP、SS的平均去除率分别为51.02%、32.5%、41.23%、58.92%,出水水质达到了国家一级B排放标准;各植物在氧化沟中发挥的作用存在较大差异,其中美人蕉对氮、磷的去除量最大,水浮莲次之,茭白和通菜的较小。