Chemical Oxygen Consumption Research Articles

Comparative evaluation of the coagulation methods effectiveness in the extraction of biologically active components from highly concentrated effluents

A characteristic feature of highly concentrated effluents is the presence of valuable components - biologically active substances, which are secondary raw materials. The effectiveness of physico-chemical coagulation and electrocoagulation methods in relation to highly concentrated wastewater from a poultry processing enterprise, as well as the prevention of the secondary pollution of the effluent supplied to biological treatment, were analyzed in the work. The objects of the study included poultry stock (suspended solids 1770.0 mg / dm3, dry residue 1920.0 mg / dm3, chemical oxygen demand (COD) 1769.0 mg O2 / dm3), iron (III) FeCl3 chloride, iron soluble electrodes as the coagulant. The objectives of study involved determination of wastewater treatment effectiveness by the studied methods (physico-chemical coagulation and electrocoagulation) with the priority indicators changing: suspended solids, dry residue, chemical consumption of oxygen, iron, chlorides, and the precipitated residue mass. As a result of testing of highly concentrated effluents with a COD index of at least 1700.0 mg O2 / dm3, it was found out that during physico-chemical coagulation with FeCl3 at a concentration of 0.75 g / dm3, the content of priority indicators decreased by no less than 60%, while the effectiveness of electrocoagulation in relation to reducing the concentration of priority indicators was at least 70%. The content of iron compounds in wastewater with the application of electrochemical coagulation was 2.08 mg / dm3, which is 34% lower than after treatment of the effluent with iron (III) chloride FeCl3 at a concentration of 0.75 g / dm3. The chloride concentration did not change. As a result of the treatment of the effluent during the coagulation of (III) FeCl3, the secondary contamination of the treated effluent and the isolated products with iron and chlorides took place. This aspect may adversely affect the subsequent biological wastewater treatment, as well as lead to a decrease in the quality of the isolated product and its use limitation. Electrocoagulation is a more preferred way of isolating valuable components in relation to physico-chemical coagulation.

Modeling of enzymatic waste water treatment

Processing and recycling of waste water is an important environmental problem. One possible and promising way to use the generated sludge is production biofertilizers for agriculture. However, in view of the risks of chemical and bacteriological contamination, it is necessary to develop technologies that ensure a high level of conditioning and stabilization of sludge. Maximum enzyme activity is observed in a microbubble medium under the conditions of a mesophilic process. To accelerate the biochemical transformation of pollutants, an enzyme-cavitation method has been developed, based on the stimulation of growth processes of microorganisms in bioreactors by low and high intensity cavitation created by turbojets. It has been established that the quality and duration of sludge treatment depends on the pressure of the substrate at the entrance to the oxidizing jets. It has been proven that at a pressure p = 0.30-0.35 MPa, the processing time of the sludge before stabilization of the chemical oxygen consumption at 16% is 8 hours. Microscopic studies found that the processed substrate is an accumulation of microorganisms with a total surface of up to 100 m2 per 1 gram of dry matter that provides high sorption properties with respect to moisture.

Kinetics of Formation of Gaseous Products in γ-Radiolysis of Mixtures Modeling Liquid Radioactive Waste

The kinetics of the formation of gaseous products and variation in the parameters of acidity (pH) and chemical oxygen consumption (COC) are studied in relation to the γ-radiolysis of aqueous solutions of mixtures of formic, oxalic, and nitric acid as the model system of radiolytic transformations of acid components of liquid radioactive waste. It is found that with an increase in the absorbed dose of γ-radiation, the acidity and the COC value both decrease because of the decrease in the concentration of organic acids in the mixture. The gaseous products CO2 and H2 were identified. Their concentrations increase nonlinearly with the absorbed dose. Radiation-chemical yields of H2 and CO2 are calculated. Using data from experiment and the literature on composition of liquid products of radiolysis of aqueous solutions of acids, kinetics of formation of gaseous products are studied using soft KINET (version 4.2.5).

Optimization of technology for processing liquid waste from meat processing plants

The existing treatment facilities of many meat processing plants are not able to provide modern requirements for the liquid waste quality. There was an urgent need for modernization and reconstruction of wastewater treatment plants, in such a way that they made it possible to achieve regulatory requirements. In the process of research, particular attention was drawn to the study of very simple technologies and facilities, which fully take into account the specific characteristics of the wastewater from meat processing plants, the actual working conditions and operation of treatment facilities. To purify wastewater from suspended substances, fat, as well as to reduce the total biological oxygen demand and chemical oxygen consumption, it is recommended to use a fundamentally new combined installation - an aerobic clearing reactor (FLOTEX - AERO) or an anaerobic clearing reactor (FLOTEX - ARO). During the design development of them the main advantages and disadvantages of the used grease skimming tanks, dirt collectors, floaters and aeration clarification units designed for incomplete biological cleaning, as well as special the specific features of the wastewater from meat processing plants were taken into account. The paper describes the dependencies for calculating the main parameters of the treatment plants.

ПРОБЛЕМЫ КАЧЕСТВА ПИТЬЕВОЙ ВОДЫ ЗАПАДНОЙ ЧАСТИ КРЫМА

Introduction. Until 2014, water supply in Sevastopol city and its municipal districts was combined due to its own surface and underground waters as well as a water conduit running from the Mezhgornoye reservoir located in the Saksky district and filled with the Dnieper waters of the North Crimean Canal. After 2014, this source was shut off. Therefore, it became important to conduct a comparative analysis of the quality of drinking water supplied to the settlements of this territorial entity. Purpose of the study: The study is aimed to assess the quality of drinking water and perform its analysis in Sevastopol city and nearby settlements, taking into account the increase in water intake from rivers and underground sources in recent years. Methods. Objects of the study are surface and underground water supply points, and drinking water for consumers. We used standard methods for the analysis of drinking water with an assessment of its physical, chemical and sanitary-bacteriological indicators using analysis of variance (AoV) methods. Water quality was assessed by the specific combinatorial index of water pollution. Using GIS technologies, maps were built to visualize a number of indicators: chemical oxygen consumption and data on the water pollution complexity coefficient at the stage when consumers receive water from the central water supply system (for all municipal districts). Results. It was established that sanitary and microbiological indicators of tap water quality — by the total microbial count, total coliform bacteria and thermo-tolerant coliform bacteria — immediately before being fed to the central water supply system in the Southern and Northern districts of Sevastopol, did not exceed sanitary standards. Due to the considerable length of the distribution networks and their high deterioration, secondary pollution of drinking water is currently taking place. In a number of municipal districts, it was revealed that the key indicators being assessed exceeded the norms of the State Sanitary Rules and Regulations. For the first time, with the help of GIS technologies in the ArcGis 10.4 software shell, specific ranks of drinking water pollution levels were distinguished for individual municipal districts, which made it possible to visualize the dynamic characteristics of polluting ingredients taking into account their territorial affiliation.

Зональные особенности химического состава вод малых рек бассейна Рыбинского водохранилища

The work is devoted to the study of the chemical composition of small rivers in the southwestern part of the territory of the Vologda region, which form the river flow of the Rybinsk reservoir basin. The determination of the chemical composition of water in rivers is carried out by generally accepted methods according to standard procedures. A distinctive feature of the river waters of the studied drainage basin is their significant difference in color and color intensity, total iron ion content, and ratio of basic anions. Most of the catchment area of this territory is represented by swamps and numerous lakes, many of them are sources of small and medium length watercourses. A comparative analysis of the ion-salt composition of the waters of rivers shows a certain similarity in the manifestation of the zonal features of the formation of their chemical composition. The composition of the water of the rivers in its salt part is mainly due to the climatic conditions. The waters of the rivers have a hydrocarbonate and sulphate-hydrocarbonate magnesium-calcium composition and relatively low mineralization. Statistical processing of the results of analytical data shows a high correlation in terms of color, permanganate oxidation and chemical oxygen consumption of the investigated water samples. Nutrients represented by the mineral forms of nitrogen and phosphorus in river waters within the studied catchment basin are determined by similar concentrations. A single directivity has been established in the distributions of the contents of heavy metal ions. From the number of heavy metal ions (iron, manganese, aluminum, copper, zinc, nickel, lead, arsenic, chromium, cadmium), which were determined in the analyzed samples, the excess of water quality standards for fishery water bodies was established of by iron and manganese ions. Excess of the established standards of quality of natural waters for other identified ions was not detected.

Mathematical simulation of wastewater cleanse processes with high content of toxic organic water pollutants

In the study the authors constructed mathematical models of wastewater treatment processes with Fenton’s reagent, ozone oxidative purification in the presence of a homogeneous catalyst, ozone oxidative purification in the presence of a heterogeneous catalyst, ozone oxidative purification in the presence of hydrogen peroxide — the Peroxon process. The resulting mathematical models allow the authors to predict the rate of chemical oxygen consumption (COD) at any time during the cleaning process, as well as to plan time expenditures to achieve the required level of this indicator. In addition, in the course of the research the integral coefficient of the models was calculated as a function of time, allowing to compare the cleaning processes and rank them by efficiency. As a result of the analysis of the integral coefficient, it was shown that the most effective is the oxidative purification of waste water with ozone in the presence of a homogeneous catalyst.

Ocean acidification and elevated temperature negatively affect recruitment, oxygen consumption and calcification of the reef-building Dendropoma cristatum early life stages: Evidence from a manipulative field study.

Expected temperature rise and seawater pH decrease may affect marine organism fitness. By a transplant experiment involving air-temperature manipulation along a natural CO2 gradient, we investigated the effects of high pCO2 (~1100 μatm) and elevated temperature (up to +2 °C than ambient conditions) on the reproductive success, recruitment, growth, shell chemical composition and oxygen consumption of the early life stages of the intertidal reef-building vermetid Dendropoma cristatum. Reproductive success was predominantly affected by temperature increase, with encapsulated embryos exhibiting higher survival in control than elevated temperature conditions, which were in turn unaffected by altered seawater pH levels. Decreasing pH (alone or in combination with temperature) significantly affected the shell growth and shell chemical composition of both embryos and recruits. Elevated temperatures along with lower pH led to decreases of ~30% oxygen consumption and ~60% recruitment. Our results suggest that the early life stages of the reef-builder D. cristatum are highly sensitive to expected environmental change, with major consequences on the intertidal vermetid reefs they build and indirectly on the high biodiversity levels they support.

Electric and Electrochemical Microfluidic Devices for Cell Analysis.

Microfluidic devices are widely used for cell analysis, including applications for single-cell analysis, healthcare, environmental monitoring, and organs-on-a-chip that mimic organs in microfluidics. Moreover, to enable high-throughput cell analysis, real-time monitoring, and non-invasive cell assays, electric and electrochemical systems have been incorporated into microfluidic devices. In this mini-review, we summarize recent advances in these systems, with applications from single cells to three-dimensional cultured cells and organs-on-a-chip. First, we summarize microfluidic devices combined with dielectrophoresis, electrophoresis, and electrowetting-on-a-dielectric for cell manipulation. Next, we review electric and electrochemical assays of cells to determine chemical section activity, and oxygen and glucose consumption activity, among other applications. In addition, we discuss recent devices designed for the electric and electrochemical collection of cell components from cells. Finally, we highlight the future directions of research in this field and their application prospects.

Модернізація технологічної лінії очищення стічних вод птахофабрики

Стан поверхневих водойм залежить від кількісного та якісного складу стічних вод підприємств, поверхневих стоків з урбанізованих та сільськогосподарських територій. Розглянуто екологічні проблеми, які виникають внаслідок потрапляння у природні водойми недоочищених стічних вод птахівничих господарств, зокрема погіршуються органолептичні показники, відбувається механічне, хімічне та бактеріологічне забруднення водойми, порушуються процеси самоочищення та погіршення гідрохімічного режиму. Доведено необхідність модернізації застарілої технологічної лінії очищення стічних вод птахофабрики, оскільки скиди в річку Недра, як водойми рибогосподарського призначення, є об'єктом державного нагляду (контролю) щоквартально. Визначено основні джерела утворення стічних вод на птахівничому господарстві. Представлено середні значення концентрацій таких забруднювальних речовин: завислі речовини, біологічне споживання кисню, хімічне споживання кисню, загальний фосфор та амонійний азот. Зазначено недоліки в роботі існуючої технологічної лінії та обґрунтовано підбір обладнання для ефективного очищення стоків. Процес очищення відбуватиметься в кілька етапів: механічне очищення, усереднення, фізико-хімічне очищення (флотація), біологічне очищення та озонування. Доцільність застосування таких методів обґрунтовано концентраціями забруднювальних речовин у стічній воді птахофабрики, відібраними щомісяця протягом 2017 р. Якість очищеної стічної води відповідатиме розрахованим показникам гранично допустимих скидів за зазначеними вище забруднювальними речовинами.

Universality of volatile corrosion inhibitors applied requirements of agricultural production

Aqualitative and quantitative system of criteria for evaluating the universality of volatile metal corrosion inhibitors (VCIs) applied to agricultural production conditions was developed. The system of qualitative criteria for universalism includes: 1- an assessment of the effectiveness of corrosion inhibition of metals under the conditions of the action of corrosion-specific stimulants present in the vapor- gas phase separately or together; 2 - suppression of various types of local corrosion caused by them in the composition of a corrosive medium; 3 - suppression in specific conditions of general and local corrosion of contacting metallic structural materials of various nature; 4 - observance of acceptable specific characteristics of VCI: ecological, class-related hazards, influence on chemical oxygen consumption (COC) and biochemical oxygen demand for the biodegradation of substances by microorganisms (BOD5). The system of quantitative criteria for universalism of the VCIs includes quantitative parameters for all the proposed qualitative items. A simplified assessment, taking into account only a part of the criteria for characterizing partially universal inhibitors, is proposed to be applied to the conditions of agricultural production. The experimental data for the volatile inhibitor IFKhAN-114 are given as an example of the effectiveness of the proposed criteria. It was shown that IFKhAN-114 is a partially universal inhi-bitor.

Review of effective tools for monitoring the performance of membrane bioreactors

The production of high quality wastewater after treatment plants using a membrane bioreactor (MBR) probably requires less control than traditional processes of activated sludge. However, the use of MBR leads to additional problems associated with the activated sludge filtration, the formation of a sediment layer on the surface of the membrane and membrane fouling. Operation engineers require simple tools for controlling and monitoring the operation of treatment plants that can provide timely information about the biological state of the activated sludge and the filterability of the waste fluid, as well as the risks of membrane contamination. To this end, effective means of monitoring MBR and methods for determining biological activity are considered. For a broader characterization of the wastewater composition, the use of total nitrogen and total carbon analyzers is considered, which have significant advantages over the analysis of chemical and biological oxygen consumption (COD, BOD).These tools can be used regularly to ensure timely intervention and more stable monitoring of the operation of MBR systems.

Textile Wastewater Treatment for Water Reuse: A Case Study

The reduced natural waters and the large amount of wastewater produced by textile industry necessitate an effective water reuse treatment. In this study, a combined two-stage water reuse treatment was established to enhance the quality and recovery rate of reused water. The primary treatment incorporated a flocculation and sedimentation system, two sand filtration units, an ozonation unit, an ultrafiltration (UF) system, and a reverse osmosis (RO) system. The second treatment included an ozonation unit, a sand filtration unit, and UF and RO systems. The color removal rate increased with the increasing ozone dosage, and the relational expression between the ozone dosage and color removal rate was fitted. Ozonation greatly reduced the color by 92.59 and 97.27 times during the primary and second ozonation stages, respectively. RO had the highest removal rate. The combined processes showed good performance in water reuse treatment. The treated, reused water satisfied the reuse standard and surpassed the drinking water standard rates for chemical oxygen consumption (CODcr), color, NH3-N, hardness, Cl−, SO42−, turbidity, Fe3+, and Cu2+. The operating cost of reuse water treatment was approximately 0.44 USD·m−3.

Reagent purification of the processing industry enterprises effluents

The article represents the results of research of the effluents purification by the reagent methods. The effluents were polluted by organic compounds of processing enterprises with small productivity. The analysis of pollution of the hydrosphere caused by the processing enterprises is carried out and the promising methods of cleaning wastewater from pollution are given. As an object of research, the streams of the production site of the fruit and vegetable juices of the Buzky Canning Factory were used. As a reagent-oxidant, sodium hypochlorite was studied. The mechanism of purification of contaminated wastewater with sodium hypochlorite is considered in detail. The task of experimental studies was to determine the flow of sodium hypochlorite where wastewater treatment is carried out to a level lower than that regulated by standards. The criterion for cleaning efficiency was two indicators of water quality: chemical oxygen consumption (COC) and dry residue. The results of the conducted studies allow us to conclude that the use of sodium hypochlorite for purification of fruit and vegetable juice from organic pollutants is promising. It is established that for effluents of the Buzky canning plant, optimal use is made for purification of effluents of hypochlorite in the ratio of 0.5 dm3/m3 of wastewater that is being purified. To ensure environmental safety from possible contamination of unreacted hypochlorite of treated wastewater, an estimation of the cost of hyprochlorite for purification and comparison of residual concentrations with normalized parameters was carried out. The kinetics of oxidation of organic impurities in effluents was also studied, which was expressed by the degree of reduction of the COC solution in the process of reacting it with sodium hypochlorite. It is proved that the kinetics of the process of oxidation of organic contaminants is described by the equation valid for monomolecular reactions. For the system under study, the rate constant of the oxidation process of organic contaminants is 0,074 1/s. The principal scheme of purification of the effluents of the Buzky canning plant by sodium hypochlorite is proposed.

Aquaculture Wastewater Treatment with Immobilized Microorganisms-aquatic Plants Strengthened Purification System

Combined purification system of microorganism - aquatic plants were established by adding immobilized 3.0 × 1010 CFU/m3 EM (Effective Microorganisms) to Eichhornia crassipes and Pistia stratiotes, to study the purification effect on prawn aquaculture water. The results showed that the purification effect of 2 groups of immobilized microorganism - aquatic plants (SEE and SEP) on ammonia nitrogen (NH4+-N), total nitrogen (TN), total phosphorus (TP) and chemical oxygen consumption (COD) were significantly better than those of the immobilized microorganism SEM group (P<0. 05). The degradation efficiency of SEE and SEP system to ammonia nitrogen were 98.37% and 96.22%. The degradation rate of TP were 90.28% and 86.11% respectively. The removal efficiency of COD were both close to 86%. At the same time, Eichhornia crassipes was slightly better than Pistia stratiotes in microorganism - aquatic plants system.

USAGE OF AERATION-OXIDATIVE JET-LOOPED INSTALLATION FOR BIOLOGICALWASTEWATER TREATMENT

Biological treatment of wastewater widely use pneumatic aeration systems, which provide sufficient concentrations of dissolved oxygen in the sludge mixture and its mixing. Reducing energy consumption of aeration remains an urgent problem. One of these methods is usage of hydromechanical aeration systems. It has known that such aeration systems have lower specific energy consumption compared to pneumatic systems. Nevertheless, hydromechanical aeration systems has limited volume performance. The simultaneous increasing of air solubility and lowering air suction in this system would increase its relative productivity.The purpose of the work is to find the design of an aerator-oxidizer and rational operation parameters to ensure the mild mixing and dissolution conditions of oxygen, in which there is no structural violation of active sludge.The operation of the aeration-oxidative jet-looped installation with various designs of oxidizer aerators and in various modes of operation using activated sludge and wastewater from the Bortnicheskaya aeration station was tested. The results of qualitative and quantitative analyzes of the active sludge before and after treatment in the installation (sludge index, microscopy) and the effect of wastewater treatment on the indicator of chemical oxygen consumption are presented. The parameters under which the activated sludge function in a satisfactory mode and the duration of this mode of operation are determined.Found that the usage of the second variant of the aeration-oxidative provides a mild mixing and aeration mode for the mixture, which does not lead to the destruction of active sludge and significant changes in its parameters. Shown a low efficiency of wastewater treatment, but a longer treatment resulted in undesirable destruction of active sludge floccules. The results of the research showed the research direction for most efficient design of the aerator-oxidizer, which will maximally reduce the above-mentioned negative phenomena and obtain high efficiency of sewage treatment by COD parameter.

Chemical characterization, antioxidant properties and oxygen consumption rate of 36 commercial oenological tannins in a model wine solution

The chemical composition (CC), antioxidant capacity (AC) and oxygen consumption rate (OCR) of 36 different commercial tannins were measured. The CC was analyzed by total polyphenol index, Bate-Smith, methyl-cellulose, Folin-Ciocalteu, OIV official method and phloroglucinolisis. The AC was measured by different methods (ABTS, CUPRAC, DPPH, FRAP, ORAC) using Trolox as standard. The OCR was measured using a non-invasive method based on luminescence. The results indicate that it is possible to obtain differentiation between procyanidins/prodelphinidins, profisetinidins/prorobinetidins, gallotannins and ellagitannins by PCA based on their CC data. It is also possible to separate condensed from hydrolysable tannins by PCA based on their AC data. The results show that ellagitannins are the fastest oxygen consumers of the various oenological tannins, followed in descending order by condensed tannins and finally gallotannins. The combination of CC, AC and OCR analyses enable to classify tannins according to their effectiveness in protecting wines against oxidation.

Larvae of Ephemeroptera group as bioindicators of water quality of the South Ural rivers

The paper contains the analysis of a possibility to use green drakes larvae of Ephemeroptera group for bioindicator researches during environmental monitoring of the South Ural rivers. Collection and analysis of types constancy of green drakes larvae was carried out in 2005 to 2016 in 17 state water posts on the territory of the South Ural rivers. As chemical characteristics the author used the index of content of compounds of manganese, nickel and iron, oil products, phenols, nitrogen ammonium, coppers, zinc, chemical oxygen consumption (COC), biological oxygen consumption in 5 days (BOC₅), sulfates, chlorides, nitrite nitrogen in river waters. In total constancy dynamics of 13 species larvae of mayflies was analyzed. The author has made a list of constant, additive and casual types of representatives of Ephemeroptera group. Significant correlative dependences between constancy of larvae of species of mayflies with a number of hydrochemical indexes are revealed statistically. The paper contains regression models for the constancy forecast of larvae of green drakes depending on concentration of the pollutant.

Research into processes of wastewater treatment at plants of meat processing industry by flotation and coagulation

The aim of present research was to select the rational method of purification of highly concentrated wastewater of meat processing enterprises. For this purpose, the optimal parameters of flotation and reagent treatment were determined. The study was conducted with two types of wastewaters. The first was formed within a week during washing meat and the equipment. Another, more concentrated and highly alkaline, was formed once a week during washing meat-smoking facilities. Less polluted wastewater should be cleaned by flotation, followed by the reagent deposition. Flotation within 1.5...2 hours eliminates almost half of the chemical consumption of oxygen. By the reagent method, using hydrated calcium oxide, previously activated by ultrasound, and the coagulant sulfate FeSO 4 , we achieved a decrease in the CCO practically to standard indicators. For the purification of more concentrated wastewater with high alkalinity, only reagent treatment is required, because of very intense foaming and carrying out the liquid phase (50...70 %) during flotation. Calcium hydroxide, activated by acoustic oscillations of ultrasonic range, should be used as reagents and iron (II) sulfate should be used as a coagulant. Based on the performed studies, the technology of wastewater treatment at meat processing enterprises with incomplete production cycle was proposed. It covers the following main stages: wastewater neutralizing, preliminary rough treatment on the bulk filter, stage-by-stage reagent treatment, filtering, and decontamination.

Combined membrane–oxythermographic method in the solution of the geochemical problems of migration of material of natural waters

Two methods for obtaining information on the fractional composition of organic matter in natural waters (membrane filtration and oxythermography) are combined in this study. The method has a number of indisputable advantages, which distinguish it among the currently available methods of analytical chemistry. In earth science, the fractional composition of organic materials in natural waters is estimated by the concentration of organic carbon (Corg) in fractions. In our opinion, an indicator of chemical consumption of oxygen (CCO) for ecological estimation of water reservoir state is more informative, because this indicator carries specific ecological information on the necessary oxygen consumption for oxidation of pollutants coming into the natural water environment. Therefore, estimation of the CCO parameter in fractions provides real information on the availability of organic matter and the probable danger from its content in water. This is the principal novelty of the information obtained and our study. The method was tested in the study of variation of the fractional composition of water matter during passage of Volga water through the waterworks (upon removal of water from the storage reservoir through the dam of the Ivan’kovskaya hydro power plant in the Dubna area). Analogous results are almost absent in earth science literature. There is a lack of data on the influence of water release through the dam even with respect to the major-component chemical composition. Variation of the fractional composition of matter (both organic and inorganic) upon water release through a waterworks is not discussed in literature. Thus, this study is of fundamental character.