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.

Advanced Treatment of Biologically Treated Chemical Comprehensive Wastewater by Nano-TiO2 Photocatalytic Oxidation

Nano-TiO2 photocatalytic oxidation was used to perform the advanced treatment of biologically treated chemical comprehensive wastewater. The effects of reaction time,nano-TiO2 dosage and initial p H of the wastewater on the removal rate of COD were tested. The GC/MS and EEM techniques were used to qualitatively analyze organic compounds in the wastewater before and after treatment. The result showed that after the biologically treated chemical comprehensive wastewater was treated by nano-TiO2 photocatalytic oxidation under the conditions of reaction time 3 h,nano-TiO2 dosage 8 g/L,and pH 8. 0,the effluent COD was 61. 9 mg/L and its removal rate was 63. 8%. Additionally,the species of organic pollutants reduced from 12 to 6. Meanwhile,the content of humic-like and fulvic-like substances dropped dramatically.

Bicarbonate activation of hydrogen peroxide: A new emerging technology for wastewater treatment

The serious limitations of available technologies for decontamination of wastewater have compelled researchers to search for alternative solutions. Catalytic treatment with hydrogen peroxide, which appears to be one of the most efficient treatment systems, is able to degrade various organics with the help of powerful ·OH radicals. This review focuses on recent progress in the use of bicarbonate activated hydrogen peroxide for wastewater treatment. The introduction of bicarbonate to pollutant treatment has led to appreciable improvements, not only in process efficiency, but also in process stability. This review describes in detail the applications of this process in homogeneous and heterogeneous systems. The enhanced degradation, limited or lack of leaching during heterogeneous degradation, and prolonged catalysts stability during degradation are salient features of this system. This review provides readers with new knowledge regarding bicarbonate, including the fact that it does not always harm pollutant degradation, and can significantly benefit degradation under some conditions.

Degradation mechanism of 2,4,6-trinitrotoluene in supercritical water oxidation

The 2,4,6-trinitrotoluene （TNT） is a potential carcinogens and TNT contaminated wastewater, which could not be effectively disposed with conventional treatments. The supercritical water oxidation （SCWO） to treat TNT contaminated wastewater was studied in this article, The TNT concentration in wastewater was measured by high-performance liquid chromatograph （HPLC） and the degraded intermediates were analyzed using GC-MS. The results showed that SCWO could degrade TNT efficiently in the presence of oxygen. The reaction temperature, pressure, residence time and oxygen excess were the main contributing factors in the process. The decomposition of TNT was accelerated as the temperature or residence time increased. At 550℃, 24 MPa, 120 s and oxygen excess 300%, TNT removal rate could exceed 99.9%. Partial oxidation occured in SCWO without oxygen. It was concluded that supercritical water was a good solvent and had excellent oxidation capability in the existence of oxygen. The main intermediates of TNT during SCWO included toluene, 1,3,5-trinitrobenzene, nitrophenol, naphthalene, fluorenone, dibutyl phthalate, alkanes and several dimers based on the intermediate analysis. Some side reactions, such as coupled reaction, hydrolysis reaction and isomerization reaction may take place simultaneously when TNT was oxidized by SCWO.

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.

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.

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.

高级氧化技术的研究现状及发展展望

为实现“绿水青山”的环保目标,废水治理技术还需要不断地优化改善。高级氧化技术因其高效、快捷、方便等优点,在众多废水处理技术中脱颖而出。本文针对电催化氧化技术、湿式氧化技术、湿式催化电氧化技术、电芬顿氧化技术等多种高级氧化技术在废水处理中的技术原理、发展现状及在应用中的优缺点进行了综述,并对高级氧化技术的未来发展进行了展望。

宜昌市某园区难降解工业废水深度处理试验及改造工程设计

工业园区难降解工业废水的经济性达标一直是亟待解决的难题。宜昌市某工业园区污水处理厂主要处理造纸厂及食品加工厂预处理后的难降解工业废水,长期存在出水不达标、运行成本高的难题。研究以现状污水处理厂难降解有机污染物为研究对象,开展了活性炭静态吸附、混凝沉淀和类芬顿催化氧化对比试验研究,比较了3种方法的处理效果。结果表明,在pH值=5.0~5.5时,类芬顿催化氧化工艺对CODCr的总体去除率最高可达73%以上,出水水质可稳定达到《城镇污水处理厂污染物排放标准》(GB 18918—2002)一级A排放标准,新增运行成本为0.905元/m^(3)。基于深度处理对比试验结果,针对该污水处理厂用地紧张的现状,结合现有土地及各构筑物单元布置情况,提出了提标改造方案,可为类似高比例工业污水厂升级改造提供参考借鉴。

水合四价铁氧化特性与生成机制的研究进展

兼具强氧化能力和选择氧化特性的水合四价铁非自由基活性组分在高级氧化水处理体系中的关键作用得到了广泛关注。文章首先综述了水合四价铁的物理化学特性、氧化动力学和氧化机制,梳理总结了以原位光谱表征、化学探针法、同位素示踪技术等为代表的水合四价铁活性组分鉴别技术,并进一步探讨了水合四价铁非自由基活性组分在亚铁/过氧化氢、亚铁/过一硫酸盐、亚铁/过二硫酸盐、亚铁/次氯酸、亚铁/高碘酸和亚铁/过氧乙酸等高级氧化体系中的生成机制。最后,结合最新的研究成果及当前研究的不足,对水合四价铁工程化应用前景进行了展望,以期为水合四价铁的相关研究和运用提供理论依据和实践指导。

芬顿催化氧化技术在化工废水处理中的应用

芬顿催化氧化技术生成强氧化性的羟基自由基,有效降解废水中的有毒或难降解有机污染物,特别是在印染、制药、焦化及造纸等化工废水处理中具有显著效果。探讨了该技术面临的挑战,如H2O2利用率低和有机物降解不完全等,并展望未来发展方向,包括催化剂改性、反应条件优化以及新型复合工艺的开发。

高级氧化法在工业废水处理领域中的应用

高级氧化法具有氧化效果好、反应快速、可提高生化降解性等特点,在处理高浓度、可生化性差、水质复杂的工业废水领域中广泛应用。首先对高级氧化法分类及其原理、特点进行简要概述,阐述了高级氧化法在电镀废水、农药废水、染料废水、制革废水、造纸废水中应用的研究进展,最后对高级氧化法的发展进行展望。

抗生素废水处理技术的研究进展

抗生素具有生物毒性、环境持久性及生物累积性,有显著的环境及健康风险。《新污染物治理行动方案》将抗生素列为重点新污染物进行管控,鼓励污水处理厂开展新污染物治理工程试点示范,形成新污染物治理示范技术。本文综述了物理法、传统化学法、高级氧化法、生物法处理抗生素废水的研究情况,指出了相应技术在抗生素废水处理技术的发展趋势。

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)。

磷化铁/生物碳复合材料活化亚硫酸盐降解橙黄Ⅱ的研究

水污染严重影响生态环境和人类健康,染料废水是其中的典型代表。利用酵母细胞作磷源和碳源,通过共沉淀-缺氧热解制备了磷化铁/生物碳复合材料,并将其作为高级氧化反应的催化剂,活化亚硫酸盐降解水体污染物橙黄Ⅱ。材料表征结果表明,磷化铁的主要组成成分为Fe_(2)P和Fe_(3)P。在较优的催化条件下,经120 min吸附和催化联合处理,模拟废水中10 mg/L的橙黄Ⅱ可以被完全去除。催化反应机理分析表明,磷化铁/生物碳复合材料通过活化亚硫酸盐产生硫酸根自由基和羟基自由基,进而实现了橙黄Ⅱ的氧化降解。

冶金渣活化过硫酸盐降解有机废水的研究进展

冶金渣作为冶金行业产生的固体废弃物,成分复杂、处理难度大,资源化利用面临挑战。将冶金渣用作催化剂,通过过硫酸盐高级氧化工艺处理有机废水是实现冶金渣资源化利用的有效方式。综述了国内外关于冶金渣作为催化剂活化过硫酸盐的最新研究进展,包括钢渣、铜渣、电解锰渣和赤泥。此外,阐述了冶金渣活化过硫酸盐工艺的强化策略。最后分析了冶金渣作为过硫酸盐催化剂在目前应用中存在的问题及未来的研究方向,以促进相关工作的发展。

微生物固定化酒糟多孔炭对亚甲基蓝的吸附和降解

为提高废弃酒糟资源化利用附加值,实现对印染废水中亚甲基蓝(MB)的高效吸附降解,采用Massibacillus菌株和酒糟多孔炭材料(DGPC)制备了微生物固定化酒糟多孔炭材料(M-DGPC)。利用FTIR、SEM和EDS对M-DGPC的结构、形貌和元素组成进行了表征。通过批量实验考察了pH和盐度对M-DGPC吸附MB性能的影响,比较了在短期实验和长期循环利用中M-DGPC对MB的吸附和降解的性能。结果表明,在pH=6和盐度为1%的环境下,M-DGPC对水中MB的48h去除率分别达到97.0%和98.6%;M-DGPC在6次循环利用后对MB的去除率约为99%,经过8次循环利用后,对MB的去除率约为93%,且MB降解率约为50%。

锰渣/H_(2)O_(2)非均相Fenton体系催化降解亚甲基蓝的研究

采用锰渣和H_(2)O_(2)构成的非均相Fenton体系降解亚甲基蓝,研究了初始pH值、H_(2)O_(2)浓度、锰渣加入量及反应温度对降解性能的影响,考察了锰渣的循环稳定性能,探讨了锰渣/H_(2)O_(2)体系去除亚甲基蓝的机理。结果表明,反应温度25℃、亚甲基蓝浓度20 mg/L、H_(2)O_(2)浓度10 mmol/L、初始pH值2.5、锰渣加入量2 g/L条件下反应120 min,锰渣/H_(2)O_(2)体系对亚甲基蓝的去除率超过98.1%;锰渣循环使用5次后,反应300 min时对亚甲基蓝的去除率仍可达95.5%。在锰渣/H_(2)O_(2)非均相Fenton体系中,·OH对亚甲基蓝的降解起主导作用。