Nutrient Removal in a Three-Step Sequencing Batch Reactor with Different Carbon Sources

A three-step sequencing batch reactor was used for nutrient (COD, NH₄-PO₄-P) removal from synthetic wastewater by using different carbon sources. The operation consisted of anaerobic, anoxic and oxic (An/Ax/Ox) phases with durations of 2/1/4.5 h. Different carbohydrates, glucose, lactose, sucrose, maltose and a mixture of glucose/maltose (50/50), were used as the sole carbon source in the first phase of experiments. Sludge age was kept constant at 10 days. Glucose was found to be the most suitable carbohydrate source with percent COD, NH₄-N and PO₄-P removals of 96%, 99% and 94%, respectively. Nutrient removals obtained with sucrose as the sole carbon source were close to those obtained with glucose. A mixture of glucose and organic acids (50/50) such as acetic, citric, propionic and butyric acid were used as carbon source in the second phase of the experiments. Maximum percent COD, NH₄-N and PO₄-P removals were 93%, 97% and 96%, respectively when a mixture of glucose and acetic acid (50/50) was used. Glucose-citric acid (50/50) combination also resulted in comparable nutrient removals.     

采用厌氧序批间歇式反应器处理屠宰废水试验研究

厌氧序批间歇式反应器(ASBR)是一种新型的厌氧反应器。应用这一工艺进行屠宰废水的处理试验。考察了ASBR工艺的运行方式、搅拌反应时间、温度、污泥负荷等对COD_cr的去除效果。结果表明,搅拌方式、温度、反应时间对ASBR处理效果影响较大,当进水COD_cr为1100～3000mg/L,反应时间24h,去除率可达75%以上。ASBR处理屠宰废水的适宜条件是:采用间歇搅拌SV₃₀=35%～46%,温度25～35℃,反应时间24h,污泥负荷0.2～0.5kg/(kgMLSS.d)     

3-Chlorophenol Biodegradation in a Sequencing Batch Reactor: Kinetic Study and Effect of the Filling Time

Mercury pollution in the Second Songhua River (SSR) was serious in the last century due to effluent from a chemical corporation. Effects of riverine self-purification on mercury removal were studied by comparing monitoring data of mercury concentrations varieties in water, sediment, and fish in the past, about 30 years. The present work suggested that a river of such a size like the SSR possessed the potential ability to recover from mercury pollution under the condition that mercury sources were cut off, though it needs a very long time, which might be several decades or even a century of years. During the 30 years with no effluent containing mercury input, total mercury (T-Hg) of water and sediment in some typical segments, mostly near the past effluent outlet, had decreased radically but still higher than the background values, though the decrease amplitudes were over 90% compared with that in 1975. T-Hg had decreased by more than 90% in most fishes, but some were still not suitable for consumption. Methylmercury concentrations (MeHg) of water, sediment, and fish were higher or close to the background levels in 2004. In the coming decades, the purification processes in the SSR would be steady and slow for a long period.     

Enhanced Microalgal Growth and Effluent Quality in Tertiary Treatment of Livestock Wastewater Using a Sequencing Batch Reactor

Water, Air, & Soil Pollution - The Pantanal is an extensive flooded plain, rich in biodiversity and considered a Biosphere Reserve and World Heritage Site. It has great complexity and can be...     

Effect of Aeration Rate on Nutrient Removal from Slaughterhouse Wastewater in Intermittently Aerated Sequencing Batch Reactors

In order to implement best environmental management practices in agricultural watershed, it is necessary to evaluate non point source pollution loads and identify critical watershed pollution sources, which are regional management priority missions. Nutrient related non point source pollutant inputs can increase primary production and intensify water eutrophication. Not all watershed areas are critical and responsible for high amount nutrient pollution losses. Implementation of watershed environmental prevention is required to assess pollution yields. Further more, identification of these critical areas is essential for the effective and efficient implementation of watershed best environmental management. In this study, a geographic information system based Soil and Water Assessment Tool was applied in Bahe River watershed, a part of the Yangtze River basin. Land use, soil series texture and daily rainfall data for a 10-year period (1996–2005) was used in this study. The calibrated model system was verified to estimate average annual Organic Nitrogen and Organic Phosphorus yields in these 10 years. The estimated results were also tested and optimized by statistical software. Based on 10-year average yearly Organic Nitrogen yield and Organic Phosphorus losses, critical sub-watersheds were identified. The five sub-watersheds in the north part of watershed were under more intensive pollution yield, west group sub-watersheds contributed to moderate losses, whereas other sub-watersheds fell under slight loading classes. The research outputs developed a basis for an effective watershed environmental management plan. The study revealed that the Soil and Water Assessment Tool could be applied successfully for identifying critical sub-watersheds for watershed best environmental management purposes.     

猪场废水生化处理工艺研究

针对猪场废水有机物、氮、磷含量高的特征，应用上流式厌氧污泥床(UASB)和序批处理反应器(SBR)相结合废水处理工艺，研究了不同水力负荷条件下对COD、BOD、氨氮去除率的影响。研究结果表明，在COD 2～8 kg/(m³·d)条件下，COD的去除率在60%～73%之间，效果较稳定；SBR在去除氨氮中效果十分明显，去除率达80%～95%。     

Chemical Reduction of Hexavalent Chromium and Its Immobilisation Under Batch Conditions Using a Slurry Reactor

Water, Air, & Soil Pollution - Risks posed by antifouling agents (irgarol 1051, diuron and dichlofluanid) to the aquatic environment of the Gulf of Napoli have been estimated. Seawater samples...     

Activated Sludge Acclimation for Hydrophobic VOC Removal in a Two-Phase Partitioning Reactor

The effect of activated sludge acclimation on the biodegradation of toluene and dimethyldisulphide (DMDS) in the presence of a non-aqueous phase liquid, polydimethylsiloxane (PDMS), in a two-phase partitioning bioreactor was characterized. The influence of the presence of PDMS, at a ratio of 25% (v/v), and acclimation of activated sludge on two hydrophobic VOC biodegradation was studied. Activated sludge were acclimated to each VOC and in the presence of the non-aqueous phase liquid, namely in the emulsion of PDMS in water. Using acclimated cells, 97.9% and 108.7% improvement of the mean biodegradation rates were recorded for toluene and DMDS, respectively, if compared to the values recorded in the absence of acclimation. While and in agreement with the lower solubility in water of DMDS if compared to toluene, a most significant effect of PDMS addition on the rate of DMDS removal was recorded, 87.0% and 153.6% for toluene and DMDS, respectively. In addition and if both biomass acclimation and PDMS addition were considered, overall improvements of the removal rates were 204% and 338% for toluene and DMDS.     

Adsorptive Removal of Pentachlorophenol by Anthracophyllum discolor in a Fixed-Bed Column Reactor

This study investigates pentachlorophenol (PCP) adsorption by the white-rot fungus Anthracophyllum discolor in a fixed-bed column reactor. PCP adsorption at different concentrations (20, 30, and 50?mg?L^?1) and pH values (5.0, 5.5, and 6.0) was determined and modeled using the Thomas model. Fourier transform infrared spectroscopy (FTIR) was used to identify functional groups of biomass that may participate in the interaction of PCP. The biosorption capacity of A. discolor was pH-dependent, and the PCP adsorbed increased with the decrease in the pH solution. Acid pH values of the influent gave an increase in saturation time in all PCP concentrations. By contrast, the increase in PCP concentration caused that the binding sites were filled quickly, resulting in a decrease in saturation time. The Thomas model was found suitable for describing the entire dynamic of the column with respect to the PCP concentration and pH of the solution. FTIR results showed that amines, carboxylates, alkanes, and C?CO groups might participate in the PCP adsorption on the biomass surface. It was concluded that A. discolor biomass was a good adsorbent for PCP removal from influent with mainly acidic pH.     

Comparison of the Performance of Membrane and Conventional Sequencing Batch Reactors Degrading 4-Chlorophenol

The biomass characteristics, the process performance, and the microbial community for a sequencing batch reactor (SBR) and a submerged membrane SBR (MSBR) were evaluated. A synthetic wastewater containing only 4-chlorophenol (4CP) was used as the sole source of carbon and energy. Degradation efficiencies of 4CP were higher than 99% for both reactors, and no significant differences on the 4CP degradation rates were observed for the SBR (116.9?±?0.9 mg 4CP g VSS^?1 h^?1) as well as for the MSBR (117.3?±?0.5 mg 4CP g VSS^?1 h^?1). Despite the similar results obtained for the physicochemical parameters, it was found that the biomass characteristics were different considering the sludge volumetric index, settling velocity, protein content in the mixer liquor, and total suspended solids in the effluent. The settling velocity was three times higher in the SBR than in the MSBR; however, a better quality, considering suspended solids, was observed for the MSBR. The protein concentration in the mixed liquor was higher in the MSBR than in the SBR, generating foaming problems in the MSBR. A similarity analysis was made with the Ochiai–Barkman index. Even though the reactors were inoculated with the same biomass, significant differences in the composition and populations dynamics were observed.     

Removal of Formic Acid from Wastewater using Three-Phase Three-Dimensional Electrode Reactor

A new electrochemical reactor, three-phase three-dimensional electrode reactor, was designed and used to investigate theremoval of formic acid from simulated wastewater. The experimental results were assessed in term of Chemical OxygenDemand (COD) removal efficiency. The results showed that the three-phase three-dimensional electrodes could effectively removeformic acid. Its COD removal efficiency was much higher than those of two-dimensional electrodes and common three-dimensionalelectrodes, respectively. The COD removal efficiency of the three-phase three-dimensional electrodes using air as a spargegas increased 13.5% relative to that using nitrogen as a spargegas. The observation indicated that the sparged air in the three-phase three-dimensional electrodes not only participated insome physical processes but also played an important role in electrochemical reactions to assist COD removal.     

序批式干态水解-液态产沼工艺在农村有机生活垃圾处理中的应用

以杭州富阳市里山镇农村生活垃圾处理场工程为例,采用序批式干态水解-液态产沼工艺对农村有机生活垃圾处理进行了应用研究。该工艺稳定运行后的最佳运行周期为60 d,运行成本为24元·t-1,处理产物具有较好的肥效。通过工程实例,证明了该工艺具有处理效果好,运行成本低等特点,为农村有机生活垃圾的资源化开发利用提供新途径。     

Batch Sorber Design Using Equilibrium and Contact Time Data for the Removal of Lead

The two-stage batch sorption design ofthe sorption of lead ions onto peat has been studiedbased on a Langmuir isotherm type equation obtainedfrom different contact time studies. A model has beendeveloped to predict the optimised minimum operatingtime to determine a specified amount of lead removal.The sorption capacity at any contact time has beenevaluated with an equation also based on themathematical form of the Langmuir equation.     

Integration of H2-Based Membrane Biofilm Reactor with RO and NF Membranes for Removal of Chromate and Selenate

A new hybrid process has been proposed and evaluated the feasibility for complete removal of chromate and selenate at high level. The process consists of a H₂-based membrane biofilm reactor (MBfR) and reverse osmosis (RO)/nanofiltration (NF) stages. The essential feature of the process is the recycling of the RO and NF concentrate into the membrane biofilm reactor. First, two different H₂-based denitrifying MBfR initially reduced selenate (Se (VI)) or chromate (Cr (III)) stably to Se° or Cr (III) to limited levels (approximately 70–85% removal for selenate and approximately 40–65% removal for chromate). In order to achieve more stable and lower levels, two different membrane (NF and RO) filtration technologies as sequential process were combined. Two wastewaters produced from two MBfRs having similar amounts of target toxic ions (C _o?=?366 μg-Cr L^?1 and C _o?=?326 μg-Se L^?1), pH, and conductivity were tested to determine the solute rejection and the membrane flux for one RO and one NF membranes at varying recovery conditions (10–90%). The results show that the rejection of solutes decreases with increasing the recovery due to the increase in osmotic pressure. The rejections by the RO membrane were >99–98% for chromate and 99–94% for selenate, while slightly lower rejections (<20%) were observed for the NF membrane at the recovery conditions.     

Sorption Removal of Anions and Cations in Single Batch Systems by Uncalcined and Calcined Mg-Al-CO3 Hydrotalcite

In this study, the sorption removal of two anions (phosphates, thiocyanates) and three cations (cadmium, lead, nickel), in single batch systems, was investigated from aqueous solutions. The process involves the sorption of the ions by hydrotalcite, which is a double-layered mixed-metal hydroxide and belongs to the family of anionic clays. The sorbent used was Mg-Al-CO₃ hydrotalcite in two forms: uncalcined and calcined at 500 °C. The calcined material showed the higher sorption capacity, for all the ions, than the uncalcined. The approximate sorption capacity of calcined material was: phosphates 250 mg g^-1, thiocyanates 80 mg g^-1, nickel/lead 100 mg g^-1 and cadmium 70 mg g^-1. The kinetic results of the anions were fitted satisfactory with the Lagergren equation. Since the sorption capacity is relatively high, hydrotalcite can be considered as a potential material for sorption of both anions and cations in wastewater treatment systems.     

Treatment of Air Polluted with Xylenes using a Biofilter Reactor

Biofiltration of air polluted by VOCs is now beingrecognized by the industrial and research communitiesto be an effective and viable alternative for theclassical environmental technologies. While a numberof biological aspects of the biofiltration process arewell understood, the effect of certain engineeringparameters such as temperature, pressure drop,bacterial count, etc., remained ambiguous especiallywhen several isomers have to be removedsimultaneously. In this paper are reported theresults of purification of air containing vapors ofxylenes in a laboratory-scale biofilter reactor. Thelatter is a packed bed of peat balls particlesspecifically designed and produced for this purpose. Three types of micro-organisms strains werescrutinizingly selected and immobilized on thefiltering material. Xylenes entering the biofilter ata relatively high inlet load (110 g m^-3 h^-1)are removed with an elimination capacity of60 g m^-3 h^-1 (at steady state). Theexperimental results obtained on the reduction ofxylenes were satisfactorily represented by thegeneralized Ottengraf's model.