Application of ferrous-hydrogen peroxide for the treatment of H-acid manufacturing process wastewater

1-Amino-8-naphthol-3,6-disulfonic acid (H-acid) is widely used in chemical industries for synthesis of direct, acid, reactive and azoic dye. The wastewater from H-acid manufacturing process is rich in various substituted derivatives of naphthalene and is one of the most hardly-treated wastewaters. A pretreatment method, ferrous ion-peroxide oxidation combined with coagulation, has been studied. The results have shown that the optimum pH value is below 4 and the suitable ferrous ion dosage is 200 mg/l. The COD removal of H-acid wastewater is about 50% and the residue have proved biodegradable when hydrogen peroxide dosage is 30 g/l. Ferrous ion-peroxide oxidation process can also improve efficiency of coagulation treatment. The overall COD removal can reach 90% or more when the concentration of ferrous ion is 200 mg/l, the dosage of hydrogen peroxide is 3 g/l and the ferric chloride dosage of two stage coagulation treatment is 15 g/l and 5 g/l, respectively. The groups on naphthalene ring, such as − + NO₂, SO⁻₃ etc., are substituted by hydroxyl free radical, and then the ring is broken down during oxidation process of H-acid.     

Application of catalytic wet air oxidation for the treatment of H-acid manufacturing process wastewater

Four types of powder catalysts whose main active components are copper (Cu), cerium (Ce), cadmium (Cd) and cobalt-bismuthide (Co-Bi) are prepared with the method of the co-deposition and are evaluated through the catalytic wet air oxidation (CWAO) treatment of H-acid solution. The comparison of the efficiencies of different catalysts shows that Ce3Cu1 (3:1) catalyst is the best one. When the reaction temperature is 200 degrees C, oxygen partial pressure is 3 MPa, pH value is 12, and reaction time is 30 min, the COD removal rate is over 90%. All the H-acid is decomposed in 5 min and is oxidized into NH4+, SO4(2-) formic acid, acetic acid and other end products. The pH value can greatly affect the COD removal and the production of organic acid. CWAO process not only can get a high reaction rate, but also can oxidize the short-chain organic acid.     

Application of multi-wavelength fluorometry for monitoring wastewater treatment process dynamics

Much of the methodology employed for characterizing wastewater and in modeling wastewater treatment processes employs off-line analysis. Off-line analysis is time consuming and not ideally suited to developing process control strategies. Clearly a rapid, inexpensive and reliable method suitable for following organic consumption and biomass production on-line would be very useful. In this study multiple excitation—multiple emission fluorometry was examined as a method for monitoring wastewater treatment processes. Results were first obtained for defined protein solutions and activated sludge to identify characteristic excitation and emission wavelength pairs. These results were then used to develop a rapid off-line assay for measurement of synthetic feeds consisting of protein substrates for batch aerobic and anoxic wastewater treatment processes and for on-line monitoring of cellular metabolic states in an anoxic process. Step-wise multiple regression and principal component analysis were employed for data analysis. The former was used to determine the most informative excitation and emission wavelength pairs while the latter was applied to reduce fluorescent spectra dimensions. Analysis of the batch kinetics suggests that this approach is valid and revealed some dynamic features of protein utilization and biomass accumulation under aerobic and anoxic conditions. A correlation was developed between COD-removal rates and the fluorescence signals in the two processes using fluorescent emission spectra rather than single signals. The data suggests that this multiple excitation—multiple emission fluorometry may be a suitable method for following wastewater and activated sludge dynamics and could be used as the basis for the development of expert system based biosensors.     

UASB法在啤酒厂废水处理中的应用

根据国内啤酒废水的水质特点,运用UASB法处理啤酒厂废水,此方法可将原废水COD值（800mg／L-3000mg／L）降低到国家规定的排放标准（≤500mg／L）,将此工艺与水解酸化池联合,可提高处理效率。     

双氧水的发泡及其在制造轻混凝土中的应用

主要研究了双氧水发泡剂在制备超轻混凝土过程中的效果,同时通过对制得混凝土的容重、气孔和强度等方面对其检测来对发泡剂进行评价。     

Evaluation of the treatment performance of a multistage ozone/hydrogen peroxide process by decomposition by-products

The performance of a multistage ozone/hydrogen peroxide (O3/H2O2) process was evaluated with respect to total organic carbon (TOC) removal of waste waters. An aqueous humic acid solution (5.2 mgC l(-1) as TOC) and a sand filtered secondary sewerage effluent (5.6mgC l(-1) as TOC) were used as model waste waters. Appropriate range of hydrogen peroxide (H2O2) dose at each stage depended upon the components of the tested solutions that changed as the process proceeded. Higher hydrogen peroxide dose was required at later stages in which low reactivity compounds with hydroxyl radical (HO*), low molecular fatty acids, were predominant. And, oxalic acid concentration related to H2O2 demand at later stages. This was assumed that the slow decomposition of oxalic acid was rate-determining step for TOC removal after its accumulation. Also, it is important to maintain dissolved ozone at low concentration for efficient TOC removal because rapid ozone consumption is required for the rapid formation of hydroxyl radical (HO*).     

Hydroxyl radical involvement in the decomposition of hydrogen peroxide by ferrous and ferric-nitrilotriacetate complexes at neutral pH

The relative rates of degradation of three hydroxyl radical probe compounds (atrazine, fenuron and parachlorobenzoic acid (pCBA)) by Fe^III/H₂O₂ (pH = 2.85), Fe^IIINTA/H₂O₂ (neutral pH), Fe^II/O₂, Fe^IINTA/O₂, Fe^II/H₂O₂ and Fe^IINTA/H₂O₂ (neutral pH) have been investigated using the competitive kinetic method. Experiments were carried out in batch and in semi-batch reactors, in the dark, at 25 °C. The data showed that the three probe compounds could be degraded by all the systems studied, and in particular by Fe^IINTA/H₂O₂ and Fe^IIINTA/H₂O₂ at neutral pH. The relative rate constants of degradation of the three probe compounds obtained for all the systems tested were identical and equal to 1.45 ± 0.03 and 0.47 ± 0.02 for k_Atrazine/k_pCBA and k_Fenuron/k_pCBA, respectively. These values as well as the decrease of the rates of degradation of the probe compounds upon the addition of hydroxyl radical scavengers (tert-butanol, bicarbonate ions) suggest that the degradation of atrazine, fenuron and pCBA by Fe^IINTA/O₂, Fe^IINTA/H₂O₂ and Fe^IIINTA/H₂O₂ is initiated by hydroxyl radicals.     

啤酒废水处理设计探讨

通过调研及小试研究方案筛选,采用以“ASBR SBR法”为主要工艺对啤酒废水进行处理,试验结果表明,其出水水质可以达到JB19821啤酒工业水污染物排放标准要求。该工艺具有操作简单、管理方便、投资省、运行费用低及占地少等优点,在啤酒废水处理领域有较好的推广价值。     

Application of a membrane bioreactor for treating explosives process wastewater

A bench-scale anoxic membrane bioreactor (MBR) system, consisting of a bioreactor coupled to a ceramic cross-flow ultrafiltration module, was evaluated to treat a synthetic wastewater containing alkaline hydrolysis byproducts (hydrolysates) of RDX. The wastewater was formulated the same as hydrolysis wastewater and consisted of acetate, formate and formaldehyde as carbon sources and nitrite and nitrate electron acceptors. The MBR system removed 80-90% of the carbon sources, and approximately 90% of the stoichiometric amount of nitrate, 60% of nitrite. The reactor was also operated over a range of transmembrane pressure, temperature, suspended solids concentration, and organic loading rate to maximize treatment efficiency and permeate flux. Increasing the transmembrane pressure and temperature did not improve flux significantly. Increasing mixed liquor volatile suspended solids (MLVSS) concentration in the bioreactor decreased the permeate flux significantly. The maximum volumetric organic loading rate was 0.72 kg COD/m3/day. The maximum food-to-mass ratio was 0.50 kg N/kg MLVSS/day and 1.82 kg COD/kg MLVSS/day. Membrane permeate was clear and essentially free of bacteria, as indicated by heterotrophic plate count. Permeate flux ranged between 0.15 and 2.0 m3/m2 day and was maintained by routine backwashing every three days. Backwashing with tap water containing chlorine bleach every fourth or fifth backwashing was able to restore membrane flux to its original value.     

Heterogeneous catalytic wet peroxide oxidation systems for the treatment of an industrial pharmaceutical wastewater

The aim of this work was to assess the treatment of wastewater coming from a pharmaceutical plant through a continuous heterogeneous catalytic wet peroxide oxidation (CWPO) process using an Fe₂O₃/SBA-15 nanocomposite catalyst. This catalyst was preliminary tested in a batch stirred tank reactor (STR), to elucidate the influence of significant parameters on the oxidation system, such as temperature, initial oxidant concentration and initial pH of the reaction medium. In that case, a temperature of 80 °C using an initial oxidant concentration corresponding to twice the theoretical stoichiometric amount for complete carbon depletion and initial pH of ca. 3 allow TOC degradation of around 50% after 200 min of contact time. Thereafter, the powder catalyst was extruded with bentonite to prepare pellets that could be used in a fixed bed reactor (FBR). Results in the up-flow FBR indicate that the catalyst shows high activity in terms of TOC mineralization (ca. 60% under steady-state conditions), with an excellent use of the oxidant and high stability of the supported iron species. The activity of the catalyst is kept constant, at least, for 55 h of reaction. Furthermore, the BOD₅/COD ratio is increased from 0.20 to 0.30, whereas the average oxidation stage (AOS) changed from 0.70 to 2.35. These two parameters show a high oxidation degree of organic compounds in the outlet effluent, which enhances its biodegradability, and favours the possibility of a subsequent coupling with a conventional biological treatment.     

Anaerobic treatment of brewary wastewater with simultaneous hydrogen production

Processes of brewery wastewater treatment with sequential use of the fermentative and bioelectrochemical methods have been investigated. A two-stage fermentation increases the rate of substrate utilization and hydrogen production. The water treatment efficiency in terms of COD in the first and second fermenters amounts to 55–65% and 65–72%, respectively. The hydrogen concentration in biogas can reach 65%. The organic acids produced in anaerobic fermentation process represent a substrate for exoelectrogenic microorganisms of bioelectrochemical fuel cell, where the secondary wastewater treatment takes place for achieving COD values of 200–400 mg/dm³. The combination of the fermentative and bioelectrochemical processes of hydrogen production makes it possible to increase its yield by a factor of 2–4 and reach the level of 7–9 moles of H₂ per 1 mole of glucose.     

Micellar enhanced ultrafiltration process for the treatment of olive mill wastewater

Olive mill wastewater (OMW) is an important environmental pollution problem, especially in the Mediterranean, which is the main olive oil production region worldwide. Environmental impact of OMW is related to its high organic load and particularly to the phytotoxic and antibacterial action of its phenolic content. In fact, polyphenols are known as powerful antioxidants with interesting nutritional and pharmaceutical properties. In the present work, the efficiency of OMW Micellar Enhanced Ultrafiltration (MEUF) treatment for removal and concentration of polyphenols was investigated, using an anionic surfactant (Sodium Dodecyl Sulfate salt, SDS) and a hydrophobic poly(vinyldene fluoride) (PVDF) membrane. The effects of the process experimental conditions on the permeate flux were investigated, and the secondary membrane resistance created by SDS molecules was evaluated. The initial fluxes of OMW processing by MEUF using SDS were 25.7 and 44.5 l/m² h under transmembrane pressures of 3.5 and 4.5 bar, respectively. The rejection rate of polyphenols without using any surfactant ranged from 5 to 28%, whereas, it reached 74% when SDS was used under optimum pH (pH 2). The MEUF provides a slightly colored permeate (about 88% less dark), which requires clearly less chemical oxygen demand (COD) for its oxidation (4.33% of the initial COD). These results showed that MEUF process can efficiently be applied to the treatment of OMW and for the concentration and recovery of polyphenols.     

Computer simulation of an industrial wastewater treatment process

The computer program REDEQL.EPAK has been modified to allow for the prediction and simulation of the chemical effect of mixing two or more aqueous solutions and one or more solid phases. In this form the program is capable of modeling the lime neutralization treatment process for acid mine waters. In its present form, the program calculates the speciation of all influent solutions, evaluates the equilibrium composition of any mixed solution and provides the stoichiometry of the liquid and solid phases produced as a result of the mixing. The program is used to predict the optimum treatment effluent composition, to determine the amount of neutralizing agent (lime) required to produce this optimum composition and to provide information which defines the mechanism controlling the treatment process.     

Biological treatment of a coal gasification process wastewater

An 8 month experimental study was performed to assess biological treatability characteristics of Hygas coal gasification process pilot plant wastewater comprised of cyclone and quench condensates. The study evaluated treatability characteristics of ammonia stripped and unstripped wastewater at full strength and at 1:1 dilution. It was determined that minimum pre-treatment required for biological oxidation consisted of reducing wastewater alkalinity, and decreasing raw ammonia concentration by dilution or by stripping. Kinetic studies with stripped Hygas wastewater showed the waste could be processed at mean cell residence times varying from 10 to 40 days with hydraulic residence times of 2–3 days; the bacteriological yield coefficient was 0.10 (COD basis), and the decay coefficient was 0.01 day⁻¹. Hygas wastewater seemed to inhibit bacteriological growth because mean cell residence times less than 10 days do not appear feasible and because apparently higher yield coefficients were observed with diluted wastewater. However, this factor should not effect removal efficiencies for organic contaminants at recommended processing conditions.     

Involvement of protozoa in anaerobic wastewater treatment process

It is only very rarely recognised in literature that anaerobic reactors may contain protozoa in addition to various bacterial and archeal groups. The role of protozoa in anaerobic degradation was studied in anaerobic continuous stirred tank reactors (CSTR) and batch tests. Anaerobic protozoa, especially the ciliated protozoa, have direct influence on the performance of CSTR at all organic loading rates (1–2 g COD l⁻¹ d⁻¹) and retention times (5–10 days). The studies revealed that chemical oxygen demand (COD) removal is strongly correlated to ciliate density in CSTR fed with oleate (suspended COD) and acetate (soluble COD). There was no significant difference in COD removal between reactors fed suspended COD and those fed soluble COD. However, the diversity and number of ciliates is greater in CSTR fed with particulate feed. The mixed liquor suspended solids (MLSS) representing biomass was significantly lower (16–34%) in CSTR with protozoa. In batch tests, increased COD removal and methane production was observed in sludge having ciliates as compared with sludge without protozoa. Methane production increased linearly with number of ciliates (R²=0.96) in batch tests with protozoa. Direct utilization of COD by flagellates and ciliates was observed in bacteria-suppressed cultures. The technological importance of these results is that reactors with protozoa-rich sludge can enhance the rate of mineralization of complex wastewater, especially wastewater containing particulate COD.     

气提升交替环流符合滤料滤池污水处理工艺的应用

介绍了气提升交替循环流复合滤料滤池的基本结构、工作原理及工艺特点,并将其应用于马鞍山市中心医院污水处理.运行结果表明,污水经该工艺处理后,CODcr、BOD5、SS及氨氮的平均去除率分别达到82.80％,88.64％,67.84％和93.72％,粪大肠菌群的灭活率在99.99％以上,且耐冲击负荷能力强,运行稳定,是一种...     

Measurement of hydrogen peroxide in an advanced oxidation process using an automated biosensor

A hydrogen peroxide biosensor was used to monitor hydrogen peroxide concentrations in a UV/hydrogen peroxide immobilised Fenton advanced oxidation process (AOP). The biosensor is based on gas phase monitoring and thus is more resistant to fouling from the liquid phase constituents of industrial processes. The biosensor is supplied with catalase continually, therefore overcoming any problems with enzyme degradation, which would occur in an immobilised enzyme biosensor. The biosensors response was linear within the experimental range 30-400mg H(2)O(2)l(-1) with a R(2) correlation of 0.99. The hydrogen peroxide monitor was used to monitor residual peroxide in an AOP, operated with a step overload of hydrogen peroxide, with correlation factors of 0.96-0.99 compared to offline hydrogen peroxide determinations by UV spectroscopy. Sparging the sample with nitrogen was found to be effective in reducing the interference from dissolved gases produced with the AOP itself. It is proposed that this biosensor could be used to improve the effectiveness of AOPs via hydrogen peroxide control.     

Modeling the UV/hydrogen peroxide advanced oxidation process using computational fluid dynamics

The use of numerical models for the design and optimization of UV/H₂O₂ systems must incorporate both reactor design (hydrodynamics, lamp orientation) and chemical kinetics (reaction mechanisms, kinetic rate constants). This study was conducted to evaluate the performance of comprehensive CFD/UV/AOP models for the degradation of an indicator organic contaminant. The combination of turbulence sub-models, fluence rate sub-models, and kinetic rate equations resulted in a comprehensive and flexible design tool for predicting the effluent chemical composition from a UV-initiated AOP reactor. The CFD model tended to under predict the percent removal of methylene blue compared to pilot reactor trials under the same operating conditions. In addition, the percent difference between the pilot and the CFD results increased with increasing flow rates. The MSSS fluence rate sub-model predicted higher contaminant removal values than the RAD-LSI sub-model while the different two-equation turbulence sub-models did not significantly impact the predicted removal for methylene blue in the tested reactor configuration. The overall degradation of methylene blue was a strong function of the second-order kinetic rate constant describing the reaction between methylene blue and the hydroxyl radical. In addition, the removal of methylene blue was sensitive to the concentration of dissolved organic carbon in the water matrix since DOC acts as a scavenger of hydroxyl radicals.     

两级A/O及其组合工艺在污水处理中的应用

对两级A/O工艺原理与处理效果进行了评述,对常见的两级A/O工艺预处理、深度处理工艺设置的功效进行了简要的分析,旨在对两级A/O工艺的推广应用起到一定的借鉴作用。     

Life cycle assessment of a coupled solar photocatalytic-biological process for wastewater treatment

A comparative life cycle assessment (LCA) of two solar-driven advanced oxidation processes, namely heterogeneous semiconductor photocatalysis and homogeneous photo-Fenton, both coupled to biological treatment, is carried out in order to identify the environmentally preferable alternative to treat industrial wastewaters containing non-biodegradable priority hazardous substances. The study is based on solar pilot plant tests using alpha-methyl-phenylglycine as a target substance. The LCA study is based on the experimental results obtained, along with data from an industrial-scale plant. The system under study includes production of the plant infrastructure, chemicals, electricity, transport of all these materials to the plant site, management of the spent catalyst by transport and landfilling, as well as treatment of the biodegradable effluent obtained in a conventional municipal wastewater treatment plant, and excess sludge treatment by incineration. Nine environmental impact categories are included in the LCA: global warming, ozone depletion, human toxicity, freshwater aquatic toxicity, photochemical ozone formation, acidification, eutrophication, energy consumption, and land use. The experimental results obtained in the pilot plant show that solar photo-Fenton is able to obtain a biodegradable effluent much faster than solar heterogeneous photocatalysis, implying that the latter would require a much larger solar collector area in an industrial application. The results of the LCA show that, an industrial wastewater treatment plant based on heterogeneous photocatalysis involves a higher environmental impact than the photo-Fenton alternative, which displays impact scores 80-90% lower in most impact categories assessed. These results are mainly due to the larger size of the solar collector field needed by the plant.