Biological Treatment Facilities Research Articles

Mathematical Model of Oxygen Regime Analysis in a Bioreactor

Purpose. Today, aeration tanks are widely used to treat industrial and municipal wastewater. Assessing the efficiency of water treatment in aeration tanks under different operating conditions is an important task. To solve this problem, it is necessary to have mathematical models that allow to quickly obtain data on the effect of treatment in aeration tanks. The main objective of this work is to develop a numerical box model to determine the efficiency of wastewater treatment in an aeration tank. Methodology. For mathematical modeling of the biological wastewater treatment process in a bioreactor, zero-dimensional material balance equations are used, which are written in relation to the concentration of substrate, activated sludge, and dissolved oxygen in wastewater. The Monod model is used to calculate the substrate oxidation process. The Euler method is used to integrate the modeling equations. A simplified model of biological water treatment in a bioreactor is considered, which makes it possible to obtain an analytical solution to the problem. The obtained analytical expression makes it possible to quickly determine the change in the concentration of dissolved oxygen in wastewater depending on the change in the concentration of activated sludge in the bioreactor. The constructed numerical model makes it possible to determine the dynamics of changes in the concentration of contaminants, activated sludge and oxygen in wastewater during their stay in the bioreactor. Findings. A tool for theoretical evaluation of the efficiency of biological wastewater treatment in an aeration tank is proposed. A numerical model has been built that allows determining the concentration of dissolved oxygen, substrate and activated sludge at the outlet of the aeration tank. Originality. An effective numerical model has been developed that allows to quickly calculate the dynamics of wastewater treatment in a bioreactor and, based on this information, to evaluate the efficiency of the reactor. Practical value. The constructed mathematical model can be useful in the reconstruction of biological wastewater treatment facilities, as well as at the design stage of bioreactors to take into account their operation under different operating conditions. A computer program has been developed that implements the constructed numerical model. The results of a computer experiment are presented.

Research of the process of biological wastewater treatment under conditions of uneven load of the treatment system

The main purpose of the article is to develop a multifactorial model for rapid assessment of the efficiency of biological wastewater treatment reactors. A mathematical model of the process of biological wastewater treatment has been developed based on: changes in the concentration of organic contaminants in the bioreactor over time, taking into account the uneven flow of wastewater to the treatment plant, the process of substrate entering the bioreactor (different amounts may enter at different times). The software implementation of the proposed algorithm for solving the corresponding model problem in Python is carried out. The results of computer experiments on the study of the efficiency of wastewater treatment in biological treatment reactors for different operating conditions of facilities are presented. In particular, such processes were considered with taking into account the unevenness of the load, because the maximum cleaning loads are in the morning and in the evening. The task was solved to simulate a real situation and show how cleaning takes place at the maximum load at a certain time of the day. The results obtained will be useful for calculations in the design of biological treatment facilities or in the reconstruction of existing bioreactors for their prospective operation under new operating conditions.

Assessing the Efficiency and Role of Duckweed (Lemna Minor) in the Removal of Pollutants from Wastewater Treatment Plant Secondary Clarifier Tanks: A Comprehensive Review

Aquatic plants, including duckweed (Lemna minor), are increasingly utilized in sewage and wastewater treat-ment to improve pollution parameters and organic matter removal. This study aimed to investigate the impacts and efficacy of duckweed in secondary clarifier tanks in a conventional biological treatment facility. The per-formance of four secondary clarifiers with and without duckweed was compared based on water quality efflu-ent and settling characteristics. As per the experiment results, the secondary clarifier tank with duckweed demonstrated higher removal efficiency for chemical oxygen demand (COD), biological oxygen demand (BOD5), ammonium, phosphate, total nitrogen (TN), and total phosphorus (TP) – of 70%, 75%, 72%, 82%, 67%, and 96%, respectively, compared to the tank without duckweed. The concentration of suspended solids in the effluent and sludge volume index (SVI) values were similar in both settings. The research findings suggest that duckweed can contribute to the treatment efficiency of conventional biological treatment plants, thus re-ducing the need for tertiary nutrient removal. Additionally, the cost-effectiveness of treatment with duckweed and its reuse as fertilizer and animal fodder make it a valuable resource. The optimal temperature for duck-weed growth is approx. +26°C, and it is influenced by sunlight and temperature more than nutrient concentra-tions.

ESTABLISHMENT OF THE LAWS OF FORMATION AND CHEMICAL COMPOSITION OF WASTEWATER OF A DAIRY PROCESSING PLANT IN THE WESTERN REGION OF UKRAINE

The dairy industry has a wide range of processing end products, which can be conventionally divided into liquid, solid and dry products. The first group includes pasteurized milk, cream and fermented milk drinks (kefir, yoghurt, desserts), the second group includes butter and cheese, the third group includes dry milk (whole or skim), proteins of various composition and purity, casein and whey. The wastewater of a dairy factory is the result of various technological and production processes, which vary in time and, accordingly, their products are not discharged simultaneously, which determines the formation of effluents of different compositions and volumes. Industrial wastewater generated at dairy factories is divided into two types: polluted and partly polluted wastewater. Polluted wastewater is produced after cleaning equipment, industrial pipelines, automobile tanks, floors, industrial premise panels, etc. Partly polluted wastewater is produced as a result of the cooling processes of milk and equipment. Both types of wastewater form a common flow that is subject to cleaning, disinfection and discharge into drainage systems or surface water bodies (depending on the chemical composition).
 The study of the wastewater composition of a dairy processing plant was divided into two stages. At the first stage, the analysis of mixed phases formed during the production process in each section of the factory was carried out.
 The analysis was carried out for one day of production at a dairy factory that processed 496 tons of whole milk, of which 170 tons were used to make whole milk products and cottage cheese, and the rest were used to make butter and casein. At the same time, 1200 m3 of water was used for all production processes, and additional water consumption for auxiliary processes and services amounted to 643 m3, so the total discharge per day was 2000.47 m3.
 The next step was to directly analyse the wastewater indicators of the dairy processing plant. To offset the impact of the production process on the composition of dairy wastewater and the volume of manufactured products, we organized sampling every two hours for four days. As a result, 48 points of analysis were obtained, which allowed us to form an objective assessment of the factory’s discharge.
 As a result of the research, the regularities and sources of formation of wastewater were established, and the chemical composition of wastewater from a dairy processing plant in the Western region of Ukraine was experimentally determined. The results obtained allowed us to draw the following conclusions. The formation of the total runoff is caused by both technological and related processes, which include sudden emissions of highly polluted wastewater with a high concentration of major pollutants, the use of different volumes of water for technological processes, and different volumes and composition of wastewater during the day. Therefore, to correctly assess the composition of a dairy factory's discharge, a systematic and long-term study is required, rather than a spot analysis.
 The chemical composition of wastewater was experimentally studied according to the main indicators regulated by the legislation of Ukraine regarding the discharge of wastewater into the sewage system and municipal biological treatment facilities. The data obtained indicates that the chemical composition of the total wastewater from the dairy processing plant does not meet the requirements. The main pollutants are: organic components, which are expressed in exceeding the chemical oxygen demand on average by three times, and at the peak load - by 10 times; phosphates in terms of total phosphorus - by 8-22 times and chlorides - by 2-7 times.
 A comparative characterization of individual technological stages shows that the most polluted wastewater is generated in the process of acid casein production. These waters are characterized by high values of COD, chlorides and phosphates, and their contribution to the overall value of these indicators is determinant. The production of whole milk products is characterized by a slight excess of COD.
 As a result, in order to prevent the death of activated sludge in municipal biological treatment facilities, pretreatment of wastewater is necessary to bring the above indicators to the norms.
 Key words: dairy industry, dairy processing plant, wastewater, wastewater chemical composition, the Western region of Ukraine.

QUANTITATIVE DETERMINATION OF THE STRENGTH OF ACTIVATED SLUDGE FLOCKS IN BIOLOGICAL TREATMENT TECHNOLOGIES

The performance of sludge and the effectiveness of wastewater treatment in various biological treatment facilities are influenced by the morphological features of activated sludge flocs. Currently, these features are assessed qualitatively through visual inspection, without statistical processing of the data. The article presents the results of quantitative determination of the strength of activated sludge flocs. A computerized method has been created to quantify the morphological characteristics of activated sludge flocs by analyzing sludge micrographs using the ImageJ software. Color and contrast indices were used to quantify the strength of the flocs. Photographs of activated sludge from the work of D. Eikelboom were used as standards for determining strength. In the calculations, we used photographs by D. Eikelboom taken at a magnification of 300 times (100 pixels) and 150 times (50 pixels). A laboratory study of the effect of Mg ions on the properties of activated sludge flocs was carried out when controlling the morphology of the flakes using the developed computerized technique. Examining the impact of Mg ions on activated sludge flocs revealed that higher magnesium concentrations in the sludge liquid result in increased linear dimensions (by 59%), floc area (by 81%) and floc volume (by 275%), but concurrently lead to a decrease in the strength of activated sludge flakes (by 21%). The obtained results in general indicated the positive effect of magnesium ion on the sedimentation properties of sludge in the aerotank-settlement system. A scale for quantitative determination of the strength of activated sludge flocs has been constructed. The developed computerized method enhances the precision and detail of visual evaluations of the technological attributes of activated sludge flocs, enabling the detection of even the smallest changes in the morphological characteristics across different wastewater treatment technologies. Keywords: activated sludge, flocs, concentration of magnesium, strength, technological characteristics.

Effects of antibiotic exposure on bioreactor treatment efficiency and dynamic migration of resistance genes in landfill leachate

Different concentrations of tetracycline (TC) (10 and 30 mg/L) were added to the anaerobic-anoxic-aerobic reactor to investigate the changes in effluent quality, sludge performance and the dynamic migration of antibiotic resistance genes (ARGs) in simulated landfill leachate. The maximum removal rates of COD, TN, and TP occurred at a TC concentration of 10 mg/L, reaching 75.99 %, 50.46 %, and 60.26 %, while the removal efficiency of NH3-N continued to decline. Microorganisms secreted abundant extracellular polymeric substance (EPS) and combined with antibiotic to form a stable and dense EPS antibiotic complex to resist adverse stress. The concentration of heavy metals showed a trend of first increasing and then decreasing, especially Mn and Zn. At a concentration of 10 mg/L TC, aerobic condition weakened ARGs, while anaerobic facilitated the proliferation of ARGs. The tetA and tetM in leachate were positively correlated with TC, TP, TN, NH3-N, and COD (P < 0.05), while the diffusion and transmission of ARGs in sludge were under the superimposed pressure of TC, various heavy metals, and EPS. Moreover, changes in bacterial communities drove the release of ARGs. To analyze the potential risks of ARGs in landfill leachate under antibiotic exposure, providing clues for the management and risk assessment of sewage biological treatment facilities.

Effect of chlorine disinfectant influx on biological sewage treatment process under the COVID-19 pandemic: Performance, mechanisms and implications

Since the onset of the COVID-19 Pandemic, large amounts of chlorine-containing disinfectants have been used to interrupt the spread of SARS-CoV-2 and residual chlorine eventually entered the hospital or municipal sewage treatment facilities. However, little is known about the effect of chlorine influx on the biological sewage treatment process. Here we investigated the effect of chlorine on the microbiome and the mechanism of microbial chlorine resistance in the activated sludge of the aerobic treatment process, using metagenomic and metatranscriptomic sequencing. We found that chlorine could negatively impact the aerobic treatment performance regarding nitrogen/COD removal with a dose-dependent effect, and the dual effects of chlorine dose and interaction time differentiated the microbial community in activated sludge. The decline of nitrogen/COD removal was attributed to the compressed activity of functional microorganisms, such as the ammonia oxidation bacteria, under chlorinated conditions, and the damage cannot be recovered in a short term. In addition, some microorganisms could survive in chlorinated conditions by up-regulating the chlorine resistance genes (CRGs) expression (approximately 1.5 times) and stimulating new CRGs expression. In particular, species Acinetobacter johnsonii could resist high concentrations of chlorine through various mechanisms, especially the overexpression of efflux pump function encoded by qac genes play a key role. Based on these results, considering the persistence of the epidemic and extensive use of chlorine disinfectants, it cannot be ignored that large amounts of residual chlorine are entering the biological treatment facility, and strictly de-chlorination measures or microbial chlorine resistance regulations before entering should be implemented.

"SOME PROBLEMS DESIGN SOLUTIONS OF SEWAGE TREATMENT PLANTS IN ASTANA"

"For the majority of Kazakhstan sewage treatment plants, the issues of modernization and construction of new blocks of wastewater treatment facilities are very relevant, the solution of which involves a comprehensive engineering and technological approach. This article analyzes the level of automation and disadvantages of the project of the second stage of sewage treatment plants (STP) of the State Enterprise «Astana SU Arnasy». The project of biological treatment on the aeration tanks of the second stage of (STP) does not provide for deep cleaning for biogenic pollutants, namely the internal recycling of activated sludge. The volume of the anoxic zone is 18 %, which is not enough for the process of biological dephosphotation. Thus, in order to more effectively achieve high-quality cleaning indicators, it is necessary to provide for a denitrification zone of at least 30 % of the total volume of the aeration tank. Analysis of the main causes of inefficient removal of phosphates at the stage of biological purification showed: insufficient concentration of biological oxygen consumption in incoming wastewater, absence of denitrification process, dephosphotation in the design of the second stage aerotanks and insufficient volume of the anaerobic zone, which is 18 % of the volume of the aerotank. The problems of inefficiency of technological wastewater treatment from phosphates at (STP) in Astana are primarily related to design errors and the impossibility of effective operation of wastewater treatment facilities associated with insufficient automation. Thus, in order to increase the efficiency of the biological treatment facilities of the second stage, it is necessary to carry out a new calculation of the facilities taking into account the processes of nitri-denitrification and biological removal of phosphates, additionally equip with equipment to ensure internal recycling with the allocation of intermediate zones and in the process of retrofitting to provide greater automation to minimize manual labor. "

Математична модель та чисельне дослідження процесу біологічного очищення стічних вод за умов нерівномірного навантаження системи очистки

The main goal of this article is to design a multifactorial model for rapid evaluation of the effec-tive operation of reactors for biological wastewater treatment, which is based on: changes in the concentration of organic pollutants in the bioreactor over time; changes in the concentration of activated sludge in the bioreactor over time; changes in the concentration of activated sludge in the reactor over time, taking into account the unevenness of the flow of wastewater to treatment facilities; the process of transporting the substrate to the bioreactor (it is possible to obtain dif-ferent amounts at different times). The software implementation of the proposed algorithm for finding the appropriate model problem in the Python environment has been developed. The re-sults of computer experiments on the study of the effectiveness of wastewater treatment in bio-logical treatment reactors for different operating modes of the installations are given. The ob-tained results will be useful during calculations in the case of designing biological treatment fa-cilities or during the reconstruction of existing bioreactors for their promising operation in new operating conditions.

Material flow and environmental performance of the source segregated biowaste composting system.

Life cycle assessment (LCA) is performed to investigate the environmental impacts of two alternative approaches in a biowaste management system. The system inventory is based on actual data and on-site sampling for two consecutive years at the mechanical and biological treatment (MBT) facility at the prefecture of Chania (Greece). The facility pertains as MBT for household waste and material recycling (MR) for the recyclable fractions in two different process lines. The mass balances and environmental performance are assessed from waste generation to end-use. The LCA and ReCiPe 2016 methodology estimate the endpoint environmental impacts on human health, ecosystem quality and resource scarcity. The results show that biowaste source segregation in an integrated waste management system not only significantly benefits its recoverability potential it also improves its environmental performance. Impacts on human health (HH) have reduced by 4.6 times, on freshwater ecosystem quality (EQf) by 6.3 times and resource scarcity (RS) usage by 2.5 times when biowaste is combined with compost production and use, material recovery and reprocessing for fertilizer and raw material substitution.

Mechanism of resistance of microorganisms to nickel compounds

The purpose of the research was to accumulate results proving the ability of biocenosis in natural water bodies and biological treatment facilities to maintain stability at nickel concentrations above the MPC up to 30% without reducing biomass growth. Studies have shown that microbial communities in the aquatic environment synchronize natural defense systems and are able to change the mechanisms of resistance. The complex formation of nickel with inorganic compounds and mixed-ligand complexes of conjugated bases of amino acids makes it possible to obtain three-dimensional spatial structures near the silt particle that bind nickel ions and thereby reduce its toxic effect.

Autonomous Pilot Plant for Continuous Biological Treatment of Sulphide Alkali Wastewater.

The article considers an autonomous pilot plant that performs continuous biological wastewater treatment in the event of emergencies at biological treatment facilities, as well as modeling the operation of biological treatment facilities when the composition of incoming wastewater changes.

Preliminary Design Analysis of Membrane Bioreactors Application in Treatment Sequences for Modernization of Wastewater Treatment Plants.

By using modeling with the Capdetworks software package, the study examines the definition of the essential elements of operational expenses at wastewater treatment facilities with a capacity of 1 to 100 thousand cubic meters per day. Four different treatment sequences were examined in the study; the first three revealed a standard setup with an activated sludge reactor and secondary clarifier (operating under various operating conditions), and the fourth scheme combined an activated sludge reactor with a submerged membrane bioreactor for sludge separation. The values of concentrations of key pollutants common for urban wastewater before treatment as well as technological parameters of operation were utilized as initial data for calculations because it was crucial to obtain conclusions that could be applied at real facilities. For each of the four treatment sequences, values for pollutants concentrations in effluent wastewater and hydraulic retention time were obtained and analyzed. The expenses of operating biological treatment facilities and treatment facilities in general, as well as the specific cost of power for treating 1 m3 of wastewater, were taken into account. Additionally, the price of purchasing membrane modules, which can be categorized as operational due to their replacement frequency of around every 7 to 10 years, was determined. The study’s findings demonstrated that the use of membrane technologies at the secondary treatment stage might significantly affect the rebuilding of wastewater treatment plants under conditions of increased capacity (flow rate) and constrained area for growth.

IMPROVEMENT OF THE MODE OF OPERATION OF BIOLOGICAL WASTEWATER TREATMENT FACILITIES

Despite the strict requirements for wastewater quality, intensive pollution and accumulation of industrial pollution, potentially hazardous substances, continues in the places of wastewater discharge. Therefore, the aim of the study is to improve the operation of biological wastewater treatment plants to ensure compliance with environmental requirements. To achieve this goal, the features of wastewater treatment are analyzed and it is found that the treatment process depends on the concentration of activated sludge, the amount of air and the properties of the wastewater entering the treatment. With this in mind, it is proposed to adjust the ratio of "sewage active sludge air" to ensure compliance with environmental requirements. Factors influencing the cleaning process are also identified. Such factors are the consumption of wastewater coming for treatment, oxygen saturation of the mixture of activated sludge and wastewater, the quantity and quality of activated sludge fed into the aeration tank. In addition, the peculiarities of the processes occurring in different parts of the buildings are taken into account, and it is proposed to divide the cleaning process into two stages. The first stage takes place in the first corridor of the aeration tank (regenerator), where the activated sludge enters for regeneration. The second stage covers the second or third corridors of the aeration tank and the secondary settling tank, where the wastewater is first mixed with activated sludge, then the mixture is discharged to the secondary settling tank. An experimental study of the cleaning process was carried out, as a result of which the necessary data for the mathematical description of the processes were obtained. After processing the experimental data, regression equations were obtained that describe the purification processes in the system "aeration tank-displacer - secondary settling tank", namely the change in the concentration of activated sludge at the outlet of the regenerator and the change in the concentration of contaminants in the purified water. The adequacy of the equations was checked according to Fisher's test. It was found that the equations are adequate to real processes within the accepted conditions and assumptions. Analytical solutions of the obtained equations allow to analyze the course of purification processes at different stages, to determine the influence of factors on the process. A procedure for the use of equations is proposed, which allows without additional experiments to choose the mode of operation of biological treatment facilities, which will ensure compliance with environmental requirements.

Challenges and Opportunities in Municipal Solid Waste Management: In the Case of Shashemene Town, West Arsi Zone, Oromia Regional State, Ethiopia

Waste adversely influences environment, economy, aesthetics and health, so it needs to be managed in order to keep the environment clean, make wise use of resources and protect public health. Hence, this study aimed to identify the challenges and opportunities in municipal solid waste management in Shashemene town, West Arsi Zone, Oromia Regional State, Ethiopia. Multistage sampling procedure including both probability and non-probability sampling techniques was employed. Data were collected from 166 residential and 34 non-residential areas respondents and analyzed with IBM SPSS and STATA/MP statistical software. Probit binary regression analysis revealed that household awareness, education level and willingness to pay for solid waste management, distance between waste disposal site and residence, and access to waste collectors were significant and positively correlated with effective solid waste management (t-test, p&lt;0.05). Notable among challenges in municipal solid waste management were inadequate collection, transportation and disposal processes whereas, source of recycling and reusing materials, energy and employment considered as opportunities. The study concluded that, there was no single waste management system in place in the town. Therefore, stakeholders need to adopt integrated SWM system. Besides, access to biological and thermal treatment facilities, waste disposal services should be improved in collaboration with and through recognition of stakeholders that build technical, financial and administrative capacity.

Life-cycle assessment of solid waste management in Dhulikhel Municipality, Nepal

Solid waste management is becoming a major environmental and public health concern in emerging municipalities in Nepal. In this study, the life-cycle assessment (LCA) approach is used to address the environmental impacts of potential waste-treatment scenarios in Dhulikhel Municipality in Nepal. The assessment was based on four different scenarios – namely, scenario 1, landfilling; scenario 2, composting combined with landfilling; scenario 3, recycling, composting and landfilling; and scenario 4, recycling, anaerobic digestion and landfilling. The LCA methodology was developed, including the benefits and impact potentials of different unit processes in each scenario, also taking into consideration emissions from energy use. The environmental impacts from the scenarios were compared in terms of global warming potential, acidification potential and eutrophication potential. Among the four scenarios, scenario 4 (i.e. with anaerobic digestion) showed the most environmental advantage. Scenarios without biological treatment facilities are the least preferred option, as their impact is significantly greater than those of other options. Therefore, organic waste is recommended not to be disposed of in landfill sites even if the transportation activity increases, because the magnitude of methane avoidance increases with an increased amount of waste diversion to the biological treatment units.

A renewable energy based waste-to-energy system with hydrogen options

A pressurized gasification combined system is studied in a novel integration with geothermal energy to produce hydrogen-enriched syngas. This system utilizes dewatered sludge, which leaves the biological wastewater treatment facility during the wastewater treatment process and is used as a feedstock to produce hydrogen as a useful output. The hydrogen produced is transformed in a proton-exchange fuel cell to electricity for community use. This system also incorporates a wind farm with a hydrogen storage system to meet societies’ energy need when the energy demand fluctuates. The integrated system is then analyzed with thermodynamic-based energy and exergy approaches. The Greater Toronto area is chosen as the case study location and comprehensive thermodynamic analysis and simulation are completed on the Aspen Plus and Engineering Equation Solver softwares while the annual wind speed data are obtained from the RETScreen software. The daily total energy delivered to the community from this proposed system is recorded to be 2.1 GWh. In addition, the hydrogen production ratio at the gasification system is observed to be 0.12 through the sludge utilization where the energy and exergy efficiencies of the integrated gasification combined cycle were calculated to be 24% and 28%, in this order. The highest energy and exergy efficiency with 38.6% and 42.2%, respectively, are observed in January where the wind farm operated at a capacity of 41.7% and the average wind speed was 6.3 m/s for Greater Toronto Area. The overall energy and exergy efficiencies of this waste-to-energy system are calculated as 32.7% and 36.6%, respectively.

Gaseous pollutants from a small-scale aerobic biological treatment facility: odor and health risk assessment

BackgroundBiological treatment technology is good for the recovery of resources and energy from municipal solid waste (MSW) and cutting down biodegradable components in landfill waste. Recently, the aerobic biological treatment of MSW has increased in rural areas of China. These facilities are usually open setup and close to nearby residents, and complaints tend to be received regarding odorous gases. A semi-in-vessel setup facility was built in recent years, and its impact on the environment and personnel is not clear.ResultsAmmonia was the predominant compound released from the windrow and its concentration was one order of magnitude higher than those of other compounds. Terpenes and reduced sulfur compounds (RSCs) persisted throughout the entire active fermentation process, with only slight decreases. The biofilter pool had a greater odor impact on the surrounding neighborhood than the waste unloading and sorting operation. The concentrations of most compounds were reduced by the biofilter pool. Ten major substances that caused odors at the facility were analyzed, where most comprised RSCs. The odor impact of the facility was low, but it was associated with a carcinogenic risk to the operators, thereby indicating the need to improve personal protection.ConclusionsLarge amounts of ammonia and volatile organic compounds were released from the composting units, but they had a low odor impact on the environment because of the semi-in-vessel setup. The odor impact of the facility was low but it was associated with a carcinogenic risk to the operators. This technology can be popularized in rural areas.

ФОСФАТСОЛЮБИЛИЗИРУЮЩИЕ БАКТЕРИИ РОДА PSEUDOMONAS И ЭФФЕКТИВНОСТЬ ИХ ПРИМЕНЕНИЯ ДЛЯ УВЕЛИЧЕНИЯ ДОСТУПНОСТИ ФОСФОРА

Phosphorus is the second most important element for plants after nitrogen. Fertilizers based on it, used to stimulate productivity, are inaccessible for most crops, which leads to their accumulation in the soil and environmental pollution. The use of phosphate-solubilizing bacteria increases the amount of phosphorus absorbed by plants. In most publications describing this group of bacteria, their effectiveness is assessed only in vitro by the halo zones formed on agar media with calcium orthophosphate. The aim of this study was to compare the solubilizing properties of bacteria of the genus Pseudomonas on a solid nutrient medium, as well as in sand and soil. It was shown that all studied cultures of microorganisms are capable of solubilizing insoluble phosphate in Pikovskaya's medium. The most active strains were Pseudomonas laurentiana ANT 56 and Pseudomonas sp. IB 182, isolated from the activated sludge of biological treatment facilities and arable soil, respectively. Experiments with the introduction of strains showed that the amount of mobile phosphorus in the sand increased 2.6-3.8 times in two weeks (in the control 1.2 times), while in the experiment with soil, a significant increase in the content of mobile phosphorus compared to the control was recorded only for the strain P . laurentiana ANT 17 (by 29.1%). It is assumed that the high solubilizing activity of the P. laurentiana ANT 17 strain may be due to the complex action of mechanisms of different nature, including the synthesis of indolyl-3-acetic acid and exopolysaccharide. The studies carried out make it possible to consider this bacterial strain as a promising object for creating on its basis a biological preparation for agricultural purposes.

Features of sewage sludge dewatering process at the use offlocculant based on epichlorohydrinand dimethylamine

The paper presents the results of experimental studies on the use of new synthesized reagent based on epichlorohydrin(chloropropylene oxide) and dimethylamine at the mechanical sludge dewatering unit; the effect of the residual flocculant content on sludge dewatering process is determined. In particular, it was found that the use of the proposed reagent led to increase in the efficiency of settling industrial effluents at the primary settling unit up to 95%; it had a beneficial effect on further wastewater treatment at biological treatment facilities, which led to 1.5-fold decrease in the consumption of flocculant. The use of this reagent made it possible to achieve a high degree of dewatering of sewage sludge and reduce the moisture content of the formed cake from 98 to 73%. Consequently, this allowedto significantlydecrease the volume of sludge further placed in sludge collectors and to reduce the amount of land allotted for its disposal.