High COD Concentration Research Articles

Carbon dissipation from surgical cotton production wastewater using macroalgae, microalgae, and activated sludge microbes.

Surgical cotton production has drastically been increased in the past few years due to excessive use by medical health professionals especially in countries like India, which is among the top three exporters of cotton worldwide. The effluent generated from surgical cotton industries differ from textile effluents by the conspicuous absence of dyeing chemicals. This wastewater has a high concentration of suspended particles, COD, dissolved ions, organic carbon, and alkaline pH. Several studies have been published on the treatment of textile effluents and the degradation of dyeing chemicals, while the treatment studies on surgical cotton wastewater have been rarely reported in spite of their potential to cause pollution in receiving land/water bodies. Activated sludge microbes have been extensively studied and well documented in the treatment of several industrial effluent but does not match to the production of valuable biomass from algae. The global energy demand has prompted the scientific community to investigate and explore the possibility of using algae for energy production with simultaneous wastewater treatment. To the best of the authors' knowledge, no research articles have been published which compare the effectiveness of activated sludge microorganisms, microalgae, and macroalgae in removing contaminants from real wastewater. To date, there is a knowledge gap in understanding and selecting the right choice of biological system for effective and economical effluent treatment. In an attempt to minimize this gap, carbon removal by microalgae, macroalgae, and activated sludge microbes were investigated on real effluent from surgical cotton industries. It was observed that the strain of Chlorella vulgaris could dissipate 83% of COD from real wastewater, while consortia of macroalgae (consisting predominantly of Ulvaceae and Chaetomorpha) and activated sludge microbes could remove 81% and 69% of the carbon, respectively. The microalgal growth (in terms of wet weight) increased from 0.15 to 0.3g, whereas the macroalgal wet weight increased from 1.5 to 3g in over 7days of batch experiments conducted in triplicates. This indicated the superlative performance of microalgae over activated sludge microbes in carbon dissipation.

USE OF GEOSTATISTICAL MODELS IN THE SPACE-TEMPORAL EVALUATION OF WATER QUALITY OF AN AMAZONIAN HYDROELECTRIC RESERVOIR

The Tucuruí Hydro-Power Complex reservoir, Pará State, Amazon Region-Brazil, as well as other reservoirs is subject to natural alterations and anthropogenic activities which in turn affect the environmental balance. The aim of this work was to verify if geostatistical models can be used in the spatial-temporal evaluation of water quality in reservoirs. The Surfer 13® software was used to interpolate the spatial distribution of data, in two years of surface water physicochemical parameters were evaluated in sixteen sampling stations. The results of the isotopic maps showed low concentrations of DO at station C1 in the Intermediate Period 2 (summer-winter), high concentration of COD at station MP in the Intermediate Period 1 (winter-summer) and increased acidity at stations C1 and C2 in summer, suggesting that the relationship between the Tucuruí Hydro-Power Complex and farming activities in the region cause impacts on the aquatic ecosystem along the reservoir.

Valorization of potato peel residues to produce a bioflocculant to be used in the treatment of liquid effluents

The present study aims primarily to investigate the flocculation capacity of a novel potato peel-based bioflocculant in wastewater treatment. The analysis of wastewater revealed high COD and BOD5 contents that could respectively reach the values 529.08 mg O2/l and 317.03 mg O2/l. In addition, the effect of experimental parameters such as the pH, coagulant/flocculant dosage, and contact time, was studied using the coagulation-flocculation treatment technique. The experiments were carried out with a lab-scale jar-test apparatus where aluminum chloride (AlCl3) was used as a coagulant agent. It should be noted that the optimal dose of AlCl3 was equal to 0.6 g at 10 mn, with turbidity reduction of 99.01%. Moreover, the flocculation tests showed higher turbidity removal (98%), for a flocculant dosage of 0.2g. The results obtained in this study indicated that using the natural potato peel-based flocculant, in the presence of a coagulant, provides an effective and environmentally friendly coagulation option for wastewater treatment.

Estimation of N2O emissions from wastewater characteristics in constructed wetlands

Conventional wastewater treatment plants (WWTPs) contribute significantly to the nitrous oxide (N2O) emissions. On the other hand, the contribution of constructed wetlands (CWs) to N2O emissions is not clear. In this study, a literature review was initially conducted to study the factors that are correlated with N2O emissions from these systems. Afterwards, a statistical formula was developed using the metaregression method for estimating N2O emission factors (EFs) from CWs. This formula related EFs with influent wastewater characteristics (chemical oxygen demand-COD, total nitrogen-TN, COD/TN) and was applied to 56 small Greek settlements for predicting N2O emissions in an alternate scenario where CWs technology would be applied instead of conventional WWTPs. The estimated N2O EFs for the alternate scenario at these settlements ranged between 0.21% and 3.20% (as N2O/TN influent load), while the average value was equal to 0.94%. The specific N2O emission was estimated to 60.82 mg N2O per day and person equivalent. The application of different scenarios with wastewater of different strength showed that the lowest N2O EF in CWs is expected for wastewater with high initial COD and TN concentrations. To compare N2O emissions from CWs and conventional WWTPs, the Ordinary Least Squares multiple regression method was also applied to develop a general statistical equation that relates N2O EFs from conventional WWTPs with wastewater characteristics. According to the results, the estimated N2O emissions from the Greek settlements for conventional wastewater treatment are larger for 77% of the studied cases compared to the emissions found if CW technology had been applied instead.

Impacts of urban and industrial pollution on functional traits of benthic macroinvertebrates: Are some traits advantageous for survival?

Urbanization and industrialization produce substantial changes in biodiversity and in the functionality of ecosystems. However, little is known about how anthropic pressures might drive these changes and about their functional consequences. We aimed to determine the responses of macroinvertebrate biological traits to urban and industrial pollution and assess the impacts of these disturbances on the functional diversity of these assemblages. We sampled benthic macroinvertebrates in 27 sites of four basins with different urban disturbance gradients (rural, peri-urban, and urban-industrial), among them the Matanza-Riachuelo River, one of the most polluted basins in the world. We classified macroinvertebrates into 11 traits and 56 categories. Then, we performed an RLQ analysis and computed functional richness, evenness, divergence and Rao diversity indexes for each site and community weighted means for each trait category. The urban and industrial sites (mainly low and middle Matanza-Riachuelo River Basin) showed high concentrations of ammonium, SRP, conductivity, COD, BOD, and organic matter, as well as the lowest values of DO. The functional richness and Rao index of these sites were significantly lower than that of the other sites. Macroinvertebrate traits associated with urban and industrial sites were aerial respiration (spiracles), forms of resistance (eggs or statoblast), cylindrical body shape, oviparity, feeding on microinvertebrates, and full water swimmers. These traits potentially enabled tolerant species persistence at polluted sites while gills, grazers, and crawlers were sensitive to these disturbances. Urban and industrial activities influence biological traits, producing the disappearance or dominance of certain traits in macroinvertebrate assemblages. As a consequence, extreme pollution caused predictable trait-based community changes resulting in reduced functional diversity, and potentially altered the ecosystem function.

When microbial electrochemistry meets UV: The applicability to high-strength real pharmaceutical industry wastewater

Wastewater from pharmaceutical and related industries contains many residual pharmaceutical components rich in color and high COD contents, which cannot be removed through the traditional wastewater treatment processes. Recently, microbial electrolysis ultraviolet cell (MEUC) process has shown its promising potential to remove recalcitrant organics because of its merits of wide pH range, iron-free, and without complications of iron sludge production. However, its application to the real pharmaceutical-rich industrial wastewater is still unknown. In this study, the MEUC process was validated with real ciprofloxacin-rich (6863.79 ± 2.21 µg L−1) industrial wastewater (6840 ± 110 mg L−1 of COD). The MEUC process achieved 100% removal of ciprofloxacin, 100% decolorization, and 99.1% removal of COD within 12, 60 and 30 h, respectively, when it was operated at pH-controlled at 7.8, applied voltage of 0.6 V, UV intensity of 10 mW cm−2, and cathodic aeration velocity of 0.005 mL min−1 mL−1. Moreover, fluorescence analysis showed that protein- and humic-like substances in such wastewater were effectively removed, providing further evidence of its high treatment efficiency. Furthermore, eco-toxicity testing with luminescent bacteria Vibro Feschri confirmed that the treated effluent was utterly non-toxic. The results demonstrated the broad application potential of MEUC technology for treating industrial wastewater.

Treatment of Dye Waste Water using Moving Bed Biofilm Reactor and Granular Activated Carbon with Neem Leaf Powder

In recent days, the waste productions from industries are increased and direct discharge of wastes causes various pollution to the environment. Wastewater treatment in textile and dye industry mainly involves treatment of highly colored wastewater containing variety of dyes in different concentrations. The dyeing industries using different types of pigments and dyes of various concentration during their several production steps. These industries discharge a wastewater which contains organic substance, high colour with high COD and low concentration of BOD. This dye waste water are directly discharge in to the streams and thus contaminate the groundwater. To treat the wastewater, which is discharge from the dyeing industries a simple physio-chemical treatment is not sufficient for the removal of pollutants. So that a biological treatment followed with a physio-chemical treatment have been required. In this study, the experiment was carried out to reduce the organic substance, high colour, COD, BOD, and Heavy metals from dye wastewater using the laboratory scale Moving Bed Biofilm Reactor followed with Granular activated Carbon bed (GAC with NLP-MBBR) with Neem leaf powder. A various thick granular activated carbon bed was used for adsorption technique and for biological treatment of wastewater. The GAC with 8cm thick is layered followed by Ennore sand with 3 grades with 4cm thick equally. Then the MBBR was operated continuously with various retention times. The polypropylene type bio balls were used for microorganism attachment in MBBR. The outlet water from the MBBR are treated using membrane process. Membrane process using moving membranes reduces the pH, organic contents, heavy metals, COD, BOD, turbidity etc., The final effluent water is suitable for Irrigation.

Effect of an Increased Particulate COD Load on the Aerobic Granular Sludge Process: A Full Scale Study

High concentrations of particulate COD (pCOD) in the influent of aerobic granular sludge (AGS) systems are often associated to small granule diameter and a large fraction of flocculent sludge. At high particulate concentrations even granule stability and process performance might be compromised. However, pilot- or full-scale studies focusing on the effect of real wastewater particulates on AGS are scarce. This study describes a 3-month period of increased particulate loading at a municipal AGS wastewater treatment plant. The pCOD concentration of the influent increased from 0.5 g COD/L to 1.3 g COD/L, by adding an untreated slaughterhouse wastewater source to the influent. Sludge concentration, waste sludge production and COD and nutrient removal performance were monitored. Furthermore, to investigate how the sludge acclimatises to a higher influent particulate content, lipase and protease hydrolytic activities were studied, as well as the microbial community composition of the sludge. The composition of the granule bed and nutrient removal efficiency did not change considerably by the increased pCOD. Interestingly, the biomass-specific hydrolytic activities of the sludge did not increase during the test period either. However, already during normal operation the aerobic granules and flocs exhibited a hydrolytic potential that exceeded the influent concentrations of proteins and lipids. Microbial community analysis also revealed a high proportion of putative hydrolysing and fermenting organisms in the sludge, both during normal operation and during the test period. The results of this study highlight the robustness of the full-scale AGS process, which can bear a substantial increase in the influent pCOD concentration during an extended period.

Assessing the water quality of Suva foreshore for the establishment of estuary and marine recreational water guidelines in the Fiji Islands.

The Standards for water quality in Fiji defined in the Environment Management Regulations 2007 only relate to effluent discharge into the environment. Urbanisation is contributing to wastewater contamination in receiving estuary and marine recreational waters, thus requiring specific guidelines. To create a baseline for this, a sampling programme with relevant physico-chemical and biological parameters was implemented at 3 sites along the Suva foreshore, for 8 consecutive months, during low and high tides. Analysis was done in triplicates, using standard methods approved for the examination of water and wastewater. In the absence of relevant Fiji guidelines, the results were compared with ANZECC (2000) guidelines for estuary and marine waters. Low DO levels, high COD, TN, NH3, TP, OP and heavy metal concentrations were measured in all 3 sites. For instance, TN and NH3 concentrations as high as 4.44 ±0.99 mg/L and 2.58 ± 0.89 mg/L respectively were recorded in Wailea river (Site 2). The colony counts for the TC, FC and E. coli were in most cases above the limits. These results confirm that wastewater discharges add to the inherent levels of parameters in receiving water bodies and support the need for specific, robust Fiji standards to better monitor water quality in foreshore areas.

Verifying the usefulness of macrophytes as an indicator of the status of small waterbodies

Small waterbodies are characterised by a high variability of physicochemical parameters. This has an impact on aquatic macrophytes, which are functional components of aquatic ecosystems that also exert a strong influence on other components of these ecosystems. Therefore, their importance in the classification of reservoirs is unquestionable. Unfortunately, the hydromacrophytes found in nutrient-rich small waterbodies in rural areas have a fairly wide ecological scale and are not suitable for a more accurate assessment of these reservoirs. In addition, indicators derived from the classification of lakes, such as phosphorus, nitrogen, chlorophyll-a, organic matter and trophic state indices, have turned out to be of little use in the assessment of small waterbodies. Only a canonical analysis taking into account both environmental variables and the occurring plant species allows satisfactory results to be obtained. Six small waterbodies located in the rural landscape of the Greater Poland Region were studied over three years. 115 plant taxa, 15 of which are hydromacrophytes, were found in the reservoirs and in their immediate vicinity. Three types of small waterbodies were identified in the CCA assessment: (i) those with high TOC, COD and ammonium nitrogen contents, dominated by pleustophytes, and in a saprotrophic state, (ii) those with high nutrient concentrations, dominated by phytoplankton, with a lack of macrophytes or with nymphaeids present, and in a hypereutrophic state, and (iii) those dominated by submerged macrophytes with low chlorophyll-a content, and in a eutrophic state. Thus, macrophytes turn out to be good indicators which support other variables in the classification of small waterbodies.

Effectiveness Analysis of Anaerobic Digestion Method in Making Biogas from Animal Manure and Tofu Liquid Waste

Organic waste has high COD and BOD content, so it is dangerous if disposed of directly into the environment. Organic waste processing, such as waste from livestock manure and liquid tofu waste, requires a process that can reduce COD and BOD levels as well as produce valuable products. Anaerobic digestion method is the proper process to convert complex compounds in waste into simpler compounds with methanogenic bacteria into a renewable energy product, namely biogas. On the other hand, the anaerobic digestion process can reduce COD and BOD levels in the biogas formation process. This study uses raw materials such as cow manure and chicken manure, and liquid tofu waste. The variables that produced the largest biogas were those with a ratio of 70% cow dung, 15% chicken manure, and 15% tofu liquid waste with a total of 3,251.5 mL. Then, the COD and BOD levels decreased significantly with more than 98% COD removal, and more than 95% BOD removal in all variables at the end of the anaerobic digestion process.

The Potential of Constructed Wetlands for Liquid Waste Management in Small and Medium-Scale Tannery: A Literature Review

The leather tanning industry or tannery, mainly in the small and medium scale (SMEs), is not environmentally friendly. Limited capitals drive the SMEs-scale tanneries to dispose of liquid waste directly into water bodies without proper treatment. It might cause serious environmental problems due to the high content of COD, BOD, chromium, and dyes. Treatment of liquid waste using constructed wetlands has been widely used because it is efficient, cheap, and powerful. This review discusses the latest studies in the wastewater treatment of tanneries using phytoremediation techniques and constructed wetlands and their potential applications in the SMEs tanneries.

Economic aspects of landfill leachate treatment using reverse osmosis membranes

Introduction. Landfill leachates contain highly concentrated organic products of waste degradation and mineral salts. Concentrations of organic matter demonstrate high COD values up to 5,000 mg/l, concentrations of ammonium ions reach 2,500 mg/l, while the total salt content may reach 15,000 mg/l. Two to three reverse osmosis treatment stages may be nee­ded to produce the water that meets effective regulations governing the composition of water discharged into the environment. Also, high salt content and COD values dramatically reduce the membrane capacity. The co-authors explored the use of nanofiltration membranes at the first stage of the leachate treatment in an effort to reduce membrane operation costs.
 Materials and methods. The experiments, conducted within the framework of this research undertaking, allowed to identify a change in the concentrations of contaminants, dissolved in the leachates of reverse osmosis and nanofiltration membranes, as well as the reduced capacity of membranes at each stage of treatment. The co-authors have studied the alternative methods that may ensure maximal reduction of the concentrate consumption in the process of leachate treatment. Principal dependencies, derived as a result of the research, enabled the co-authors to identify the concentrate consumption rates depending on the extent of treatment focused on ammonium ions. The co-authors describe the methodology employed to identify the area of membranes at each treatment stage depending on the leachate composition.
 Results. Calculations of operating costs are provided for three compositions of leachates, typical for the Moscow region, depending on the treatment methodology and further recovery of membrane concentrates.
 Conclusions. Nanofiltration membranes can be used at the first stage of the landfill leachate treatment in the case of high COD and salt content. The application of nanofiltration membranes allows to reduce the concentrate consumption rate and cut operating costs. A new technology is developed to split the concentrate into two flows: the flow that has a high organic matter content, and the flow that has a high content of mineral salts, sodium and ammonium chlorides in order to facilitate the recovery of the concentrate.

Short-time irrigation on young olive tree (Olea europaea L. cv. Chemlali) with untreated industrial poultry wastewater: investigation of growth parameters and leaves chemical composition.

The purpose of this study was to evaluate the short-term irrigation effect with industrial poultry wastewater on young olive trees (Olea europaea L. cv. Chemlali). Industrial poultry wastewater can be considered as a bio-fertilizer due to its richness in nutritive elements (SO42-, HCO3-, total nitrogen, and K+). The physicochemical analysis of wastewater showed a high concentration of TSS, COD, BOD, COT, NO3-, and conductivity. Measurements indicated that poultry wastewater enhanced plant growth, leaves dry matter, and ashes in comparison with tap water, as well as poultry wastewater diluted with tap water; however, a decrease in total soluble sugars (glucose and fructose) was detected in leaves. The determination of fatty acid profile of young olive trees leaves irrigated with poultry wastewater showed richness on saturated fatty acids in comparison with mono- and poly-unsaturated ones. In addition, oleic acid (C18:1) presented the lowest content in leaves of trees irrigated with poultry wastewater irrigation. According to those results, poultry wastewater lends itself to being a hydric alternative and at the same time a source of nutrients that can help fill the water deficit in semi-arid countries and avoid costly waste disposal for slaughterhouses.

The assessment of the amount of water pollution and its suitability for drinking of the Ty\u015bmienica River Basin, Poland

The quality and potability of waters of the Tyśmienica River Basin were determined in 2017 at eight measuring stations. The paper presents analyses of the physical and chemical parameters of surface waters of the basin. With regard to suspended solids, pH value, electric conductivity, sulphates, ammonia, chlorides and phosphate, the water was classified as having a very good ecological status. In the case of Kjeldahl nitrogen, the waters were classified as having a good ecological status. In the case of the remaining parameters, i.e. BOD, DO, TOC and COD, the status varied among stations. The values of all the physical and chemical parameters complied with the values for undisturbed conditions. Only ammonia and COD showed significant differences among stations. The WPI values for each measuring point ranged from 0.90 to 1.56, what corresponds to the descriptive indicators of moderately polluted water. The high concentrations of COD and TOC indicate that high-performance treatment processes (category A3) must be used to ensure that the water is suitable for drinking.

Eficiencia en la remoción de materia orgánica mediante lombrifiltros (Eisenia foetida) en aguas residuales domésticas para zonas rurales

El inadecuado manejo de las aguas residuales domésticas en zonas rurales vertidas en cuerpos hídricos sin previo tratamiento constituye un gran problema de polución ambiental, así como un riesgo para la salud pública. El propósito del este estudio fue evaluar la eficiencia de la remoción de materia orgánica mediante lombrifiltros en las aguas residuales domésticas de una zona rural. En condiciones experimentales, se diseñó el lombrifiltro utilizando como base teórica el sistema de tratamiento Tohá —creado por el Dr. José Tohá— conformado por cuatro estratos: aserrín + Eisenia foetida, carbón activado, grava y piedras de río. Se evaluó la concentración de materia orgánica del afluente obteniendo elevadas concentraciones de DBO5, DQO, SST y ST. T1 alcanzó los mayores porcentajes de eficiencia con un flujo volumétrico de 1.8×10-2 l/s y TRH de 0.92 h obteniendo 52.25 % para DBO5 y DQO, 66.74 % de SST y 52.91 % de ST. De esta manera, se determinó que la utilización de lombrifiltros a base de Eisenia foetida para remover la materia orgánica representa un sistema de tratamiento ecológico e innovador que requiere una baja inversión, es eficiente y amigable con el ambiente.

Optimization of aeration time on GAS-SBR system to remove organic content in wastewater

In general, chicken slaughterhouses have slaughtering capacity of more than 40,000 chickens per day, resulting in high volume wastewater with high BOD and COD concentration. Therefore, appropriate wastewater treatment technology is needed. Granular Activated Sludge that uses Sequencing Batch Reactor (GAS-SBR) has ability to treat wastewater with high organic content. The study is conducted to analyze the ability of GAS to reduce organic content with variation of aeration time in reaction stage on SBR. Formation of Granular Activated Sludge (GAS) was cultured by reacting activated sludge and using a stirring of 20 rpm. SBR had a total work volume of 45 liters and was operated in 5 stages, namely the filling, the reaction with aeration, the settling, the decantation, and the stabilization stage. In this study the initial COD concentration in chicken slaughterhouse effluent (RPA) was 5440 mg/L. The result of the study was that highest removal of BOD and COD parameter occured at 3 hours’ aeration time with removal efficiency 75% and 72%, while for TSS was at 5 hours’ aeration time with removal efficiency 65%. It could be concluded that GAS in SBR system could be applied to remove high organic content parameters in wastewater.

Anaerobic digestion of dissolved air floatation slurries: Effect of substrate concentration and pH

Dissolved air floatation (DAF) slurries are an unconventional substrate for anaerobic digestion owing to their high COD concentrations, mainly consisting of lipids. Batch anaerobic digestion of DAF slurry was conducted to investigate the methane production through dilution of the slurry (with mineral salt medium, MSM) and by adjusting the initial pH (to 6.0, 5.5, 5.0 and 4.5) The performance of two different inocula, namely waste activated sludge (WAS) treating domestic wastewater and anaerobic granular sludge (AGS) treating dairy wastewater, was compared. The DAF slurry had a pH of 7.03 ( ± 0.07), conductivity of 6.69 ( ± 0.54) mS/cm, and a COD and ammonium concentration of 85.96 ( ± 8.32) g/L and 168.49 ( ± 1.79) mg N/L, respectively. DAF slurry without dilution produced a maximum methane yield of 58.60 ( ± 1.97) mL/g COD after 30 days of incubation. Dilution with MSM up to three folds, improved the methane yield by about 67%–105% and 67%–177% with WAS and AGS as the inoculum, respectively. Higher methane productivity was achieved at an inoculum to substrate ratio of at least 1.5 for WAS and 2.0 for AGS, respectively. AGS was more effective with a 20% increase in methane production from 3-fold diluted DAF slurry when compared with WAS. Adjustment of the initial pH of the DAF slurry to 6.0 resulted in a methane yield of 359.71 ( ± 32.72) mL/g COD, which was 23% higher than the control without pH adjustment. This study demonstrated that the methane yield from DAF slurries can be enhanced through substrate dilution and initial pH adjustment. • Methane yield enhanced by 23% upon adjustment of initial pH of the DAF slurry to 6.0. • 3-fold dilution increased methane production rate by 275% with granular sludge. • Anaerobic granular sludge is an efficient inoculum for methanogenesis of DAF slurry. • Lag phase duration was not shortened by dilution or pH adjustment of the DAF slurry. • Optimal inoculum to substrate ratio at least 1.5 and 2.0 for WAS and AGS, respectively.

Analysis of Key Technologies for Industrialized Treatment of Fatty Acid High-Salinity Organic Wastewater

Objectives : Wastewater produced by fatty acid production contains high concentration of organic substances and high concentration of salts (mainly sodium sulfate), causing great pollution to water resources and environment. The pollution prevention and control of this type of wastewater are very necessary. The key to treating this type of wastewater is to remove salts and COD to achieve harmless treatment. This is a problem in wastewater management that has plagued the industry for a long time. This paper proposed a technique suitable for fatty acid high salinity organic wastewater.Methods : First, the industrial treatment technology of organic wastewater with high salinity was introduced and analyzed. Combined with the principle of industrial wastewater treatment, the process route for the treatment of fatty acid high salinity organic wastewater was analyzed and selected. In addition, the key technology and process for anaerobic desalination and COD removal were analyzed and selected.Results and Discussion : According to the unique nature of this type of wastewater mainly containing sulphate salts and the feasibility of industrial production, a special technology combination was proposed to treat this wastewater at this stage. Since this wastewater has a B/C ratio of 0.4 to 0.45, it is easier to use biological treatment method. Thus, the conventional treatment method is pretreatment + biological treatment. Biological enhancement and reactor process optimization can be studied for better efficiency.Conclusions : Considering the high COD and sulphate concentration characteristics of fatty acid high-salinity organic wastewater, high-efficiency anaerobic biochemical treatment is mainly considered. Combined with modern high-efficiency anaerobic suspended sludge granule technology, it was concluded that pretreatment + high efficiency IC anaerobic + secondary biological treatment can achieve industrialized treatment of such wastewater in a targeted, low-cost and reliable way. In the later stage, bio-enhancement of the anaerobic process as well as structural and process optimization of the reactor can be carried out to obtain better technical and economic results in production practice.

Size class segregation of Arctic cod (Boreogadus saida) in a shallow High Arctic embayment

Arctic cod (Boreogadus saida (Lepechin, 1774)) vertically segregate by size class in deep waters, but such dynamics had not been explored in shallow waters. Spatial distribution of Arctic cod was investigated in Resolute Bay, Nunavut, Canada (74°41N, 94°52W) from 20 July to 5 August 2012, using a combination of hydroacoustic survey and direct capture. Hydroacoustic surveys identified two high concentrations of Arctic cod, with larger individuals detected on the west side, and smaller individuals on the east. Catch data confirmed size segregation, with fish sampled on the west side of the bay significantly larger (mean = 174 mm total length (TL); 35.9 g weight (WT)) than those on the east (mean = 110 mm TL; 9.2 g WT). Fish density on the west was estimated at 3.52 fish·m−2, extrapolated to the full 0.52 km2 of the surveyed shoal to ∼1 830 400 fish and 65 711 kg (assuming a 35.9 g mean WT). Smaller fish on the east side were more abundant (9.32 fish·m−2; total abundance ∼11 836 400 fish or 108 894 kg; mean WT = 9.2 g). Horizontal habitat-partitioning was observed between Arctic cod size classes over a small geographic area (∼8 km2), most probably due to partitioned resources and to mitigate predation risk.