Removal Of Soluble Organic Matter Research Articles

The treatment of petrochemical wastewater via ozone-persulfate coupled catalytic oxidation: mechanism of removal of soluble organic matter.

Petrochemical wastewater contains a variety of organic pollutants. Advanced oxidation processes (AOPs) are used for deep petrochemical wastewater treatment with distinct advantages, including the complete mineralization of organic substances, minimal residual byproducts, and compatibility with biological treatment systems. This work evaluates the effectiveness of three methods, namely, ozone, persulfate, and O3-PMS (ozone-persulfate) processes, which were compared to remove soluble organic matter. The O3-PMS process offered significant advantages in terms of organic matter removal efficiency. This process involves ozone dissolution in an aqueous persulfate solution, producing a more significant amount of hydroxyl radicals in comparison to single AOPs. The production of hydroxyl radicals and the synergistic effect of hydroxyl radicals and persulfate radicals were investigated. In the O3-PMS process, transition metal ions were added to understand the mechanism of the O3-PMS coupled catalytic oxidation system. The results showed that when the ozone concentration was in the range of 5 ~ 25mg/L, the dosage of persulfate was in the range of 0.01 ~ 0.05mol/L, the dosage of metal compounds was in the range of 0:0 ~ 2:1, and the reaction time was in the range of 0 ~ 2h; the optimum chemical oxygen demand (CODCr) and total organic content (TOC) removal effect was achieved under the coupled system with an ozone concentration of 10mg/L, a persulfate dosage of 0.02mol/L, a 1:2 dosage ratio of between Fe2+ and Cu2+ compounds, and a reaction time of 2h. Under optimal reaction conditions, the rates of CODCr and TOC removal reached 70% and 79.3%, respectively. Furthermore, the removal kinetics of the O3-PMS coupled catalytic oxidation system was analyzed to optimize the removal conditions of COD and TOC, and the mechanism regulating the degradation of dissolved organic matter was explored by three-dimensional fluorescence and GC-MS technology. Thus, O3-PMS coupled catalytic oxidation is an effective process for the deep treatment of wastewater. The careful selection of transition metal ions serves as a theoretical foundation for the subsequent preparation of catalysts for the ozone persulfate oxidation system, and this study provides a suitable reference for removing organic matter from petrochemical wastewater.

Heavy metal and soluble organic matter removal using natural conglomerate and siltstone soils: Towards soil aquifer treatment for oily wastewater

The present work aims to assess the viability of vadose zone siltstone and conglomerate for oil and gas-produced water (PW) treatment using soil aquifer treatment (SAT). Comprehensive batch adsorption tests were carried out to analyze siltstone and conglomerate removal capacity for dissolved organics (phenol), and heavy metal ions (Ni 2+, and Zn 2+). The results demonstrated that conglomerate displayed a 98% removal capacity for Zn 2+ and 88% for Ni2+ while siltstone showed 82% removal for Zn2+ and 88% removal for Ni 2+. However, both siltstone and conglomerate showed low phenol removal (32% for siltstone, and 9% for conglomerate). The equilibrium adsorption isotherms were fitted by several adsorption models. The Langmuir model exhibited the best fitting for the adsorptions of phenol, Ni 2+ ions, and Zn 2+ ions on the two soils. The kinetics studies have revealed that phenol, Ni 2+ ions, and Zn 2+ ions adsorption on the two soil samples obey a pseudo-second-order kinetic model. Furthermore, Fourier transform infrared spectroscopy studies revealed that the Si-O peak in the soil plays a predominant role in interactions with heavy metal ions and phenol due to its high content in the soils. However, the electrostatic interactions between functional groups (Si-O, CO32-, and CO carbonyl groups) of the soil samples and the Ni2+ ions, Zn2+ ions, and phenol also contributed to the removal capacity. It is revealed that Zn2+ has a greater affinity for carboxyl groups than Ni2+. The obtained data in this study would support the effective design of SAT treatment for PW and help in reducing the risk of contaminating the groundwater aquifer.

Solvent extraction efficiency of an Eocene-aged organic-rich lacustrine shale

To study nano-scale inorganic pore systems in shale plays, the removal of soluble organic matter (SOM) using solvent extraction is an important pre-treatment step to reduce the in-situ petroleum blockage effect in shale oil samples. However, factors controlling the extraction efficiency are not well-understood, making the reliability and consistency of this extraction process questionable. In this work, an oil window mature organic-rich lacustrine shale in the Bohai Bay Basin of East China was prepared in six different sample sizes (from 1 cm cubes down to <75 μm powder), extracted for different times (1 day–25 days), and analysed for chemical composition to assess the extraction efficiency and behaviour, in order to arrive at a consistent workflow for sample pre-treatment for pore structure characterization. In general, the smaller the sample is used and the longer the sample is extracted, the higher the extract yield is obtained. The maximum extraction efficiency (based on the amount of extract after 25 days for the powder sample) is highly correlated with the sample size, indicating that there would always be residual soluble material in larger-sized samples even after extraction for a month. Molecular examination of the extract reveals that the early extract is dominated by saturated hydrocarbons, and these in turn are enriched in n-alkanes, while the saturated hydrocarbon content declines relative to aromatic and polar fractions, and the saturates are more dominated by branched and cyclic hydrocarbons, as extraction time increases. Such a knowledge about the extraction time- and sample size-dependencies of the extraction rate are fundamentally important in designing the solvent extraction protocol prior to carrying out nano-petrophysical studies.

Molecular differences in sequential extracts obtained by core flooding of the early mature ultra-tight Posidonia Shale

The here analyzed Posidonia Shale (PS) samples have relatively high total organic carbon (TOC) contents greater than 2 wt% and are thermally early mature. They, thus, already experienced some generation of petroleum and contain abundant bitumen in the pore space. Solvent core flooding extraction was performed on five clay- and carbonate-rich early-mature Posidonia Shale plugs using dichloromethane (DCM) as permeating fluid under controlled confining pressure in a tri-axial flow cell. Molecular characteristics and differences were observed in original, sequential and residual extracts obtained by core flooding. Furthermore, porosity and permeability changes due to removal of soluble organic matter were recorded. Our results show that core flooding extraction of the clay-rich shales failed due to their low permeability (3.0–5.0 nD), while sequential extraction was successfully performed on the carbonate-rich shales. Acidic compounds were flushed out first, which indicate that these compounds might be preferentially expelled during the early stage of primary migration. Pristane and phytane are preferentially expelled in the whole process of expulsion as compared to n-alkanes. Composition of the other aliphatic (including n-alkanes, hopanes and steranes) and aromatic (including methylnaphthalenes, phenanthrenes, dibenzothiophenes and methyldibenzothiophenes) compounds of the sequential, original and residual extracts do not exhibit much difference. Statistical data indicate that the original and residual extracts have higher similarity and show lower apparent maturity than the sequential extracts indicating that expelled oil might show higher maturity than the related source rock. This observation might be important for interpreting oil/source rock correlations based on geochemical parameters. Porosities of the carbonate-rich shales were slightly smaller than those of the clay-rich rocks, while the permeability is much higher in the carbonate-rich lithologies. It is worth noting that porosity and permeability did not increase during the extraction of soluble organic matter. On the contrary, due to counteracting compaction effects that reduce pore volume extraction lead to an overall porosity and permeability decrease.

Impacts of Continuous Inflow of Low Concentrations of Silver Nanoparticles on Biological Performance and Microbial Communities of Aerobic Heterotrophic Wastewater Biofilm.

Attached-growth wastewater processes are currently used in water resource recovery facilities (WRRFs) for required upgrades due to an increase in influent loading or to reach more stringent discharge criteria. Yet, the distribution and long-term inhibitory effects of silver nanoparticles (AgNPs) in attached-growth biological wastewater processes and their impact on involved microbial communities are poorly understood at relevant, low concentrations. Retention, distribution, and long-term inhibitory effect of polyvinylpyrrolidone (PVP)-coated AgNPs were evaluated in bench-scale moving bed biofilm reactors (MBBRs), achieving soluble organic matter removal, over a 64 day exposure to nominal concentrations of 10 and 100 μg/L. Distributions of continuously added AgNPs were characterized in the influent, bioreactor, and effluent of MBBRs using single particle inductively coupled plasma mass spectroscopy (spICP-MS). Aerobic heterotrophic biofilms in MBBRs demonstrated limited retention capacity for AgNPs over long-term exposure, with release of AgNPs, and Ag-rich biofilm sloughed from the carriers. Continuous exposure to both influent AgNP concentrations significantly decreased soluble chemical oxygen demand (SCOD) removal efficiency (11% to 31%) and reduced biofilm viability (8% to 30%). Specific activities of both intracellular dehydrogenase (DHA) and extracellular α-glucosidase (α-Glu) and protease (PRO) enzymes were significantly inhibited (8% to 39%) with an observed NP dose-dependent intracellular reactive oxygen species (ROS) production and shift in biofilm microbial community composition by day 64. Our results indicated that long-term exposure to AgNPs in biofilm processes at environmentally relevant concentrations can impact the treatment process stability and the quality of the discharged effluent.

Comparison of performance in an anaerobic digestion process: one-reactor vs two-reactor configurations

The present work compares two types of configurations for a two-reaction (acidogenesis and methanogenesis) anaerobic digestion model. These configurations are as follows: (i) a single bioreactor, where the acidogenesis and methanogenesis reactions occur inside and, (ii) two bioreactors connected sequentially, where each reaction occurs separately in each reactor. The mathematical models that describe the mentioned configurations are analyzed at steady state, comparing the following criteria: the stability of the processes (stability properties of desired equilibria) and soluble organic matter removal performance (substrate levels at steady states), concluding that separation of the reactions in two bioreactors does not improve the stability of the process nor the soluble organic matter removal capacity, unless the improvement of the growth functions of both microorganism populations is considerably important at the moment of separating them into two reactors.

COD removal from biologically stabilized landfill leachate using Advanced Oxidation Processes (AOPs)

The removal of soluble organic matter from mature landfill leachate by means of biological, chemical, and combined biological-chemical methods was investigated in this study. Aerobic sequencing batch reactor (SBR) with activated sludge was used as the biological treatment to remove ammonium. The chemical treatments included ozone (O3), ozone + hydrogen peroxide (O3 + H2O2), Fenton’s reagents (H2O2 + Fe2+), and ozone + Fenton’s reagents (O3 + H2O2 + Fe2+). Results indicated that the SBR achieved approximately 25% Chemical Oxygen Demand (COD) removal with an initial COD of 1276 mg/L. Ozonation of raw leachate achieved 16% COD removal after 240 min of treatment while O3 + H2O2 achieved 33% COD removal of raw leachate with 900 mg/L H2O2 in 120 min. Moreover, Fenton’s process also achieved 33% COD removal from raw leachate. Results suggest that the biological treatment followed by chemical treatments had the most efficient COD removal. After biological stabilization, ozonation removed 52% of the COD within 240 min. The Fenton’s process achieved 67% COD removal using equal doses of H2O2 and Fe2+. However, Fenton’s reagents in conjunction with O3 removed 69% and 72% COD in 120 min and 240 min, respectively. The dosage test also revealed that the 2:1 ratio of H2O2 and Fe2+ had the best COD removal. Therefore, these results indicate that the combination of biological and post-chemical treatment methods effectively remove organic pollutants from mature landfill leachate.

Fate and inhibitory effect of silver nanoparticles in high rate moving bed biofilm reactors

Municipal water resource recovery facilities are the primary recipients of a significant fraction of discharged silver nanoparticle (AgNP)-containing wastes, yet the fate and potential risks of AgNPs in attached-growth biological wastewater treatment processes are poorly understood. The fate and inhibitory effects of polyvinylpyrrolidone (PVP)-coated AgNPs at environmentally-relevant nominal concentrations (10, 100, 600 μg/L) were investigated, for the first time, in high rate moving bed biofilm reactors (MBBRs) for soluble organic matter removal. The behavior and removal of continuously added AgNPs were characterized using single-particle inductively coupled plasma mass spectrometry (spICP-MS). While no inhibitory effect at average influent concentration of 10.8 μg/L Ag was observed, soluble COD removal efficiency was significantly decreased at 131 μg/L Ag in 18 days and 631 μg/L Ag in 5 days with suppressed biofilm viability. The inhibitory effect of AgNPs on treatment efficiency was highly correlated to the retained mass of total Ag in attached biofilm on the carriers. Biofilm demonstrated limited retention capacity for AgNPs over 18 days. Considerable mass of Ag (38% to 75%) was released via effluent, predominantly as NPs. We detected some chemically transformed and potentially less toxic forms of silver nanoparticles (Ag2S, AgCl), over the exposure period. This study demonstrated the distinct interaction dynamics, bioavailability and inhibitory effects of AgNPs in a biofilm system. Release of bioavailable AgNPs via effluent and AgNP-rich biofilm, sloughing off the carriers, can affect the treatment chain efficiency of downstream processes. Thus, the inhibitory effects of AgNPs can be a concern even at concentrations as low as 100 to 600 μg/L Ag in biological attached growth wastewater treatments.

Nonlinear system identification of the dissolved oxygen to effluent ammonia dynamics in an activated sludge process

Aeration of biological reactors in wastewater treatment plants is important to obtain a high removal of soluble organic matter as well as for nitrification but requires a significant use of energy. It is hence of importance to control the aeration rate, for example, by ammonium feedback control. The goal of this paper is to model the dynamics from the set point of an existing dissolved oxygen controller to effluent ammonia using two types of system identification methods for a Hammerstein model, including a newly developed recursive variant. The models are estimated and evaluated using noise corrupted data from a complex mechanistic model (Activated Sludge Model no.1). The performance of the estimated nonlinear models are compared with an estimated linear model and it is shown that the nonlinear models give a significantly better fit to the data. The resulting models may be used for adaptive control (using the recursive Hammerstein variant), gain-scheduling control, L2 stability analysis, and model based fault detection.

Photosynthetic bacteria-based membrane bioreactor as post-treatment of an anaerobic membrane bioreactor effluent

Anaerobic membrane bioreactors have attracted increasing interest in the field of wastewater treatment. However, significant amounts of organic matter, nitrogen and sulphide in the effluent may limit its reuse. A photosynthetic bacteria-based membrane bioreactor is proposed for the further treatment of this effluent. A pilot-scale unit was run outdoor for over 900h to assess the process performance at short hydraulic retention time. After an initial biomass development, simultaneous removal of soluble organic matter and nitrogen was achieved (65% and 39%, respectively). In addition, a significant concentration of sulphate was detected in the permeate, revealing an evident sulphide oxidation. Despite the accumulation of biopolymer clusters in the biological suspension, membrane fouling was effectively mitigated by air-aided backwashing, allowing a sustainable operation. Several strains of bacteria were identified including the photoheterotrophic bacteria Rhodopseudomonas sp. and the nitrifying and denitrifying bacteria Chryseobacterium sp.

Sedimentological Study and Heavy Mineral Analysis of Sediment Samples from Well-S, Niger Delta, Nigeria

Sedimentological study and petrographic analyses were carried out on thirty ditch cutting samples from well-S, Niger Delta, Nigeria, with the aim of determining the provenance and depositional environment of the sediments. The samples were subjected to soxhlet extraction for the removal of soluble organic matter from them and particle size analyses using Pipette and Emery sedimentation techniques in order to determine the grain size distribution of the sediments. Separation of heavy of mineral from the samples was done with the aid of bromoform to enable petrographic analyses of the heavy mineral suite, under the polarising microscope. The data obtained from the grain size analysis were used in preparing histograms, from which some simple statistical parameters were derived. Graphic mean values obtained range between 0.74 and 2.64 O, which implies that the sediments are predominantly fine-medium grained. The inclusive standard deviation values ranges from 0.53 to 1.24 O, indicating that the sediments are moderately well sorted to moderately sorted. Inclusive graphic skewness values of 0.29 to 0.70 indicate that the sediments ranges from finely skewed to strongly finely skewed and the graphic kurtosis values of 0.61 to 1.54 shows that the sediments are predominately very platykurtic which implies a low energy environment of deposition. The polymodal nature displayed by the histograms indicates that the sediments have been derived from various sources. The study concluded that the sediments were deposited in a fluvial environment. It also established that the sediments originate from metamorphic and acid igneous rocks of the Nigeria Basement Complex and mineralogically mature to sub-mature.

Flow-through extraction of oil and gas shales under controlled stress using organic solvents: Implications for organic matter-related porosity and permeability changes with thermal maturity

Four core plugs from the Lower Jurassic Posidonia Shale of the Hils Syncline in northern Germany have been subjected to flow-through extraction tests with dichloromethane (DCM) under controlled stress conditions in a tri-axial flow cell. The samples represent a maturity sequence from 0.53 to 1.45% VRr. The bitumen sequentially extracted from the natural pore space of the shale plugs was analyzed for its geochemical composition. Changes in rock matrix density, porosity and permeability resulting from the removal of soluble organic matter were determined. The relative porosity increase of the plugs after extraction ranged from 6 to 13% and correlated with the extract yield. Klinkenberg-corrected permeability coefficients measured with helium increased by a factor of 17.0 for the immature/early mature sample and 26.6 for the overmature sample. Petrographical investigations after extraction indicate that fluid flow occurred predominantly parallel to bedding as evidenced by open fractures and fractures bearing residues that apparently precipitated from the DCM solution. Compositional variations of the extracts over time are interpreted in terms of the organic geochemical inventory of bitumen associated with the natural pore system and its accessibility at different maturity levels. These patterns deviate strongly from the bulk rock extracts of the powdered samples.

Advanced water treatment using a meshed synthetic tube as biological filter media in pilot plant scale

ABSTRACT The purpose of this study is to remove suspended solids (SS) and soluble organic matter from waste water using meshed synthetic tubes, made of synthetic poly propylene fiber to allow free water flow from any direction. The capacity of 450 m3/d pilot plant was operated to treat effluent of secondary settling tank in sewage treatment plant. Removals of SS, soluble organic matter and phosphorus (w/additional chemical treatment), were monitored. As a result, maximum SS-loading rate for the plant was found 3.8 kg SS/m3 d, and operation time was limited up to 45 h, and the maximum linear velocity was found 16 m3/m2 h. The maximum SS removal for each unit reactor was 7.1 kg/cage m3. With the meshed tube biofilter, not only SS but also soluble organic matter removal and nitrification were observed. Because of its relatively fast filtration rate and high filtration capacity, it seemed to be used properly as a direct filtration.

Effect of temperature on the performance of microbial fuel cells

Single and double chamber microbial fuel cells (MFCs) were tested in batch mode at different temperatures ranging from 4 to 35 °C; results were analysed in terms of efficiency in soluble organic matter removal and capability of energy generation. Brewery wastewater diluted in domestic wastewater (initial soluble chemical oxygen demand of 1200 and 492 mg L −1 of volatile suspended solids) was the source of carbon and inoculum for the experiments. Control reactors (sealed container with support for biofilm formation) as well as baseline reactors (sealed container with no support) were run in parallel to the MFCs at each temperature to assess the differences between water treatment including electrochemical processes and conventional anaerobic digestion (in the presence of a biofilm, or by planktonic cells). MFCs showed improvements regarding rate and extent of COD removal in comparison to control and baseline reactors at low temperatures (4, 8 and 15 °C), whilst differences became negligible at higher temperatures (20, 25, 30 and 35 °C). Temperature was a crucial factor in the yield of MFCs both, for COD removal and electricity production, with results that ranged from 58% final COD removal and maximum power of 15.1 mW m −3 reactor (8.1 mW m −2 cathode) during polarization at 4 °C, to 94% final COD removal and maximum power of 174.0 mW m −3 reactor (92.8 mW m −2 cathode) at 35 °C for single chamber MFCs with carbon cloth-based cathodes. Bioelectrochemical processes in these MFCs were found to have a temperature coefficient, Q10 of 1.6. A membrane-based cathode configuration was tested and gave promising results at 4 °C, where a maximum power output of 294.6 mW m −3 reactor (98.1 mW m −2 cathode) was obtained during polarization and a maximum Coulombic efficiency ( Y Q) of 25% was achieved. This exceeded the performance at 35 °C with cloth-based cathodes (174.0 mW m −3; Y Q 1.76%).

Electricity generation and treatment of paper recycling wastewater using a microbial fuel cell

Increased interest in sustainable agriculture and bio-based industries requires that we find more energy-efficient methods for treating cellulose-containing wastewaters. We examined the effectiveness of simultaneous electricity production and treatment of a paper recycling plant wastewater using microbial fuel cells. Treatment efficiency was limited by wastewater conductivity. When a 50 mM phosphate buffer solution (PBS, 5.9 mS/cm) was added to the wastewater, power densities reached 501+/-20 mW/m2, with a coulombic efficiency of 16+/-2%. There was efficient removal of soluble organic matter, with 73+/-1% removed based on soluble chemical oxygen demand (SCOD) and only slightly greater total removal (76+/-4%) based on total COD (TCOD) over a 500-h batch cycle. Cellulose was nearly completely removed (96+/-1%) during treatment. Further increasing the conductivity (100 mM PBS) increased power to 672+/-27 mW/m2. In contrast, only 144+/-7 mW/m2 was produced using an unamended wastewater (0.8 mS/cm) with TCOD, SCOD, and cellulose removals of 29+/-1%, 51+/-2%, and 16+/-1% (350-h batch cycle). These results demonstrate limitations to treatment efficiencies with actual wastewaters caused by solution conductivity compared to laboratory experiments under more optimal conditions.

Effect of the organic loading rate on the performance of anaerobic acidogenic fermentation of two-phase olive mill solid residue

A study of the effect of the organic loading rate (OLR) on the anaerobic acidogenic fermentation of two-phase olive mill solid residue (OMSR) derived from fruits with a low ripening index was carried out in a laboratory-scale completely stirred tank reactor at mesophilic temperature (35 degrees C). Eight experimental runs were carried out at OLRs of 3.2, 5.6, 7.4, 9.6, 11.0, 12.9, 14.0 and 15.1g T-COD/ld, which were equivalent to hydraulic retention times of 50.0, 28.8, 21.8, 16.9, 14.7, 12.4, 11.5 and 10.7d, respectively. The experimental results obtained demonstrated that the optimum value of OLR for the acidogenic fermentation process was 12.9 g T-COD/ld, for which a maximum production of acetic acid was achieved. It was found that inhibition of the process occurred at OLRs higher than 12.9 g T-COD/ld. This was characterized by a significant decrease in the acetic acid concentration in the effluent and an increase in the concentration of other volatile acids that may affect the methanogenic step. The process inhibition was also characterized by the plateau in the curves of the effluent substrate concentration versus the OLR applied. It was found that a first-order kinetics satisfactorily described the influence of non-acetic acid soluble organic matter concentration (S-COD( *)) on the rate of soluble organic matter conversion to acetic acid (R(S-COD)( *)), and the influence of acetic acid concentration (AcH) on the rate of acetic acid production (R(AcH)), while a potential equation type adequately described the influence of acetic acid concentration on the volumetric hydrogen production (R(ACH) ). The kinetic constant for soluble organic matter removal was 0.145 d(-1), while the constant for acetic acid formation was found to be 0.075 d(-1).

Treatment of packaging board whitewater in anaerobic/aerobic biokidney

Whitewater from production of packaging board was treated in a combined anaerobic/aerobic biokidney, both in laboratory scale and pilot plant experiments. Both the laboratory experiments and the pilot plant trial demonstrate that a combined anaerobic/aerobic process is suitable for treating whitewater from a packaging mill. It is also possible to operate the process at the prevailing whitewater temperature. In the laboratory under mesophilic conditions the maximal organic load was 12 kg COD/m3*d on the anaerobic reactor and 6.7 kg COD/m3*d on the aerobic reactor. This gave a hydraulic retention time, HRT, in the anaerobic reactor of 10 hours and 2 hours in the aerobic reactor. The reduction of COD was between 85 and 90% after the first stage and the total reduction was between 88 to 93%. Under thermophilic conditions in the laboratory the organic load was slightly lower than 9.6 COD/m3*d and between 10 and 16 COD/m3*d, respectively. The HRT was 16.5 and 3.4 hours and the removal was around 75% after the anaerobic reactor and 87% after the total process. For the pilot plant experiment at a mill the HRT in the anaerobic step varied between 3 and 17 hours and the corresponding organic load between 4 and 44 kg COD/m3*d. The HRT in the aerobic step varied between 1 and 6 hours and the organic load between 1.5 and 26 kg COD/m3*d. The removal of soluble organic matter was 78% in the anaerobic step and 86% after the combined treatment at the lowest loading level. The removal efficiency at the highest loading level was about 65% in the anaerobic step and 77% after the aerobic step. In the pilot plant trial the removal efficiency was not markedly affected by the variations in whitewater composition that were caused by change of production. The variations, however, made the manual control of the nutrient dosage inadequate and resulted in large variations in effluent nutrient concentration. This demonstrates the need for an automatic nutrient dosage system. The first step towards such a system was to evaluate two different on-line instruments. Both had severe stability problems, which made them unsuitable as parts in a system for control of the nutrient dosage.

Anaerobic sequencing batch reactor treatment of dilute wastewater at psychrophilic temperatures

Anaerobic treatment of dilute wastewater was studied using three laboratory‐scale anaerobic sequencing batch reactors (ASBRs), each with an active volume of 6 L. The reactors were fed a synthetic substrate made from nonfat dry milk supplemented with nutrients and trace metals. The chemical oxygen demand (COD) and 5‐day biochemical oxygen demand (BOD5) of the feed were 600 mg/L and 285 mg/L, respectively. Steady‐state performance data were collected over a time period of 2 years at reactor temperatures of 5, 7.5, 10, 12.5, 15, 17.5, 20, and 25°C. Hydraulic retention times (HRTs) were maintained at 24, 16, 12, 8, and 6 hours. Steady‐state process kinetics and removal efficiencies were evaluated for the various conditions. Results showed that the ASBR process was capable of achieving more than 90% soluble COD (SCOD) and BOD5, removal at temperatures of 20°C and 25°C at all HRTs. At a temperature of 5°C and a 6‐hour HRT, SCOD and BOD5, removals were 62% and 75%, respectively. At intermediate temperatures ranging from 5 to 25°C and HRTs between 24 and 6 hours, removal of soluble organic matter ranged from 62 to 90% for COD and from 75 to 90% for BOD5. In all cases, solids retention times were high enough to maintain good performance. Substrate removal rates and half‐saturation coefficients were also determined at all temperatures. The temperature correction coefficient was determined to be 1.08 in the temperature range of 7.5 to 25°C. It is concluded that the ASBR has unique characteristics that enable efficient removal of organics during treatment of dilute wastewaters at low temperatures.

Removal of soluble organic matter from rock samples with a flow-through extraction cell

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTRemoval of soluble organic matter from rock samples with a flow-through extraction cellMatthias. Radke, Hans G. Sittardt, and Dietrich H. WelteCite this: Anal. Chem. 1978, 50, 4, 663–665Publication Date (Print):April 1, 1978Publication History Published online1 May 2002Published inissue 1 April 1978https://doi.org/10.1021/ac50026a035RIGHTS & PERMISSIONSArticle Views366Altmetric-Citations85LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (365 KB) Get e-Alerts Get e-Alerts

Minimal Solids Aeration Activated Sludge

Modifications of the activated sludge process were sought to allow for more rapid and economical treatment of high strength, biologically degradable, organic wastes. Complete mixing activated sludge systems were tested on a laboratory scale to observe their performance under high organic volumetric loadings and short solids retention times. The systems operated effectively under these conditions, with percentages of removal of soluble organic matter from solution approaching those of conventional activated sludge as long as the systems were maintained aerobically. This type of activated sludge operation, however, produced a larger volume of biological solids than conventional activated sludge. Consequently, investigations were made, and data is reported on the feasibility of using either moderate or extended solids aeration complete mixing activated sludge, chemical treatment, or an oxidation pond for treatment of the biological solids wasted from these highly loaded, highly wasted, complete mixing activated sludge systems.