Tag:wastewater sludges

№7|2016

ENVIRONMENTAL PROTECTION

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UDC 504.06

PANKOVA G. A., Rublevskaya O. N., Leonov L. V.

SUE «Vodokanal of St. Petersburg»’s activities in the field  of mitigating the negative environmental impact

Summary

The results of the SUE «Vodokanal of St. Petersburg»’s activities on eliminating raw sewage discharges into the city water bodies are presented. The use of advanced technologies that provided for reducing nutrients discharge with effluents of the wastewater treatment facilities is described, as well as the solution of the problem of wastewater sludge handling and utilization by introducing incineration technology that provided for abandoning sludge storing at special municipal landfills. The new and upcoming trends of the SUE «Vodokanal of St. Petersburg»’s activities on mitigating the negative environmental impact: storm water volume metering and treatment; snow utilization; tackling the problem of hazardous pollutants, micro plastics and pharmaceuticals in particular, are laid. With the purpose of further reduction of pollutant discharges into the receiving water bodies (with raw sewage) the developed «St. Petersburg water supply and wastewater disposal development Scheme till 2025 inclusive of the 2030 prospects» envisages complete elimination of raw combined and domestic wastewater discharges into receiving water bodies before 2022; elimination after 2030 of discharge of 50% of surface runoff without treatment into the separate municipal storm sewer (at present only 2% of surface runoff passes treatment). The Scheme includes a comprehensive information database on the water supply and wastewater disposal systems as well as the urban planning documents and schemes prepared for other directions of engineering and energy complex of St. Petersburg.

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№4|2013

WASTEWATER SLUDGE HANDLING

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UDC 628.31.006.82

Belyaeva S. D., Korotkova E. V.

New national standards for the wastewater sludge utilization and disposal

Summary

The new Russian Federation standards have been developed: GOST R 54534-2011 «Resources conservation. Wastewater sludges. Requirements to the utilization for disturbed lands reclamation»; GOST R 5453-2011 «Resources conservation. Wastewater sludges. Requirements to the disposal to landfills». The standards set the requirements to wastewater sludge when used for disturbed lands remediation and landfilling. Different methods of sludge treatment that provide for meeting the requirements set by the standards including natural seasoning on stabilization beds, blending with inert materials, composting with organic filler etc. are considered.

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№11|2014

WASTEWATER SLUDGE TREATMENT

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UDC 628.336.411

Ivanov A. N., Ivanova M. G.

Wastewater sludge dewatering with the use of «Sibfloc®» flocculant and special wells

Summary

The technology of high-efficient wastewater sludge dewatering on sludge beds with the use of brand new «Sibfloc®» flocculant made on the basis of polyethylene oxide and special slotted wells for the collection and removal of sludge water is described. The technology has been tested under various climatic conditions – from the Krasnoyarsk Area to the Krasnodar Area and introduced at the wastewater treatment facilities in Russia and Kazakhstan. The suggested technology when used on sludge beds provides for wastewater sludge dewatering to 68–75% moisture content; under the effect of «Sibfloc®» flocculant the sludge is structurized and readily dried to 40–45% moisture content after unloading from the sludge bed. The sludge generated during dewatering is suitable for any type of utilization – from direct use as soil conditioner for reclamation of dumps and solid waste landfills to processing into fertilizers and soil for forest plantation. Sludge not suitable for any utilization because of fast drying capability to any moisture content (from 60 to 8%) can be efficiently used in biogas generating plants or special furnaces either in its initial state or in the form of fuel bricks. Technical and economic performance and environmental effect of using the considered technology allow classifying it as a best available technology. Introducing the technology of wastewater sludge dewatering with the use of «Sibfloc®» flocculant provides for 4–7 times reduction of the required number of sludge beds, and improvement of sanitary and environmental situation at the treatment facilities and adjacent territories, including efficient odor control and unloading filled up sludge beds and sludge tanks.

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№10|2018

WASTEWATER SLUDGE TREATMENT

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UDC 628.336

Rublevskaya O. N., Vasiliev B. V., Protasovskii E. M., Petrov S. V.

Wastewater sludge processing and utilization at the wastewater treatment facilities of Saint-Petersburg: best practices and prospects

Summary

Best practices of processing and utilization of wastewater sludge at the wastewater treatment facilities of Saint-Petersburg is presented. Centrifuging is used as the main dewatering technology. The dewatering equipment for 40 years has been continuously upgraded; at present decanters – latest generation equipment are used that provide for 72–75% dewatered sludge moisture content and sludge incineration without any fuel addition. All sludge generated at the municipal treatment facilities in the city is incinerated at three incineration plants. Sludge is incinerated in fluidized bed furnaces at 800–850 °С. Ash after sludge incineration is classified as hazard class IV. The amount of sludge is reduced 12-fold. As a result storing dewatered sludge at special landfills was abandoned; consequently the need of constructing new ones was no longer valid. Flue gas cleaning is carried out by wet scrubbing (incineration plants at the Central Wastewater Treatment Facilities and South-Western Wastewater Treatment Facilities) and dry scrubbing. At present the project of upgrading the incineration plant at the Central Wastewater Treatment Facilities has been designed.

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№07|2015

WASTEWATER SLUDGE TREATMENT

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UDC 628.336.71

PANKOVA G. A., Petrov S. V.

The experience of operating wastewater sludge incineration plants  at SUE «Vodokanal of St. Petersburg»

Summary

The experience of operating wastewater sludge incineration plants at the facilities of SUE «Vodokanal of St. Petersburg» is reported. The technology of fluidized-bed sludge incineration is described. The process takes place by means of the calorific capacity of dewatered wastewater sludge. The heat generated in the process of incineration is a secondary energy resource and is utilized in the process for heating blast air, working area and generation of electrical power at the wastewater treatment facilities. The processes of cleaning flue gases generated in the incineration process are compared. The methods of wet and dry flue gas scrubbing are used at the sludge inci­neration facilities. The quality of scrubbed gases meets the regulatory requirements. The measures taken for improving the reliability and efficiency of operating the plant at the Central wastewater treatment plant of St. Petersburg are described. The experience gained was taken into account in designing sludge incineration facilities at the South-West and North wastewater treatment plants. All the plants adopted the technology of fluidized-bed incineration of sludge. The plants provide for incinerating the entire amount of sludge generated at the wastewater treatment facilities of St. Petersburg.

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№5|2018

WASTEWATER SLUDGE TREATMENT

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UDC 628.336

Koulakov A. A., Terekhova E. M., Kutsevol M. A.

Improvement of municipal wastewater sludge treatment methods

Summary

The introduction of the process schemes of removing nitrogen and phosphorus from wastewater demands a customized approach to handling the generated sludge. Permanent residence of sludge during thickening in anoxic conditions results in its septicity, deterioration of dewatering properties and phosphorus yield into supernatant. The results of the study of possible enhancement of municipal wastewater sludge thickening processes through the example of the Vologda wastewater treatment facilities that use nitrification-denitrification and biological dephosphorization in wastewater treatment are presented. During sludge dewatering in belt filter presses two return flows are generated – filtrate and washwater. Filtrate contains residual flocculant that can be reused. It was found that adding 10–15% filtrate from the dewatering facilities to the sludge during thickening resulted in increasing the thickening rate within first 30 minutes of the process, in particular; this fact provides for almost double reduction of the sludge amount. It is noted that 3 hours preaeration of sludge during thickening reduces the time of thickening by increasing the settling rate from 0.8 to 1.2–1.4 mm/min. A process flow scheme of sludge processing that includes two-stage thickening with preaeration and filtrate dosing and subsequent mechanical dewatering has been developed. Combining preaeration and filtrate dosing provides for reducing the sludge thickening time to 3–6 hours; improving its dewatering properties and reducing the dosage of flocculant during dewatering.

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№6|2017

WASTEWATER SLUDGE TREATMENT

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UDC 628.336.71:628.477.8

LOBANOV F. I., Maurin Eric, Plekhanov A. V.

Thermal treatment – a promising trend in wastewater sludge utilization

Summary

The presence of toxic elements in wastewater sludge generated at the wastewater treatment facilities precludes from using to the full extent the biosludge rich in nitrogen, phosphorus and potassium as efficient organic or combined organomineral fertilizers and potting soil for reclamation of disturbed lands. In this context the task of developing advanced technologies of wastewater sludge treatment in order to mitigate the negative impact on the environment with the use of different passivation methods of active forms of toxic metals has been set. The information on metal furnaces made of hi-tech alloy with fluidized bed for thermal treatment of wastewater sludge is presented in comparison with furnaces made of chamotte brick. Compact modular furnaces have been designed for incinerating 2000–6000 tons of sludge annually at small-scale wastewater treatment facilities. Furnaces for medium and large-scale wastewater treatment facilities have been designed for incinerating from 6000 to 80000 tons of sludge annually. The use of mineral additives and different inorganic sorbents ensures efficient treatment of waste gases. It is shown that metal furnaces with patented design have advantages compared to the traditional furnaces made of chamotte brick particularly when used at small-scale wastewater biological treatment facilities.

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№9|2018

WASTEWATER SLUDGE TREATMENT

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UDC 628.336.71

Duambekov M. S., Ivanov A. N., Ivanova N. V.

«Organic belt around Kazakhstan cities – 2020» environmental project

Summary

The description of «Organic belt around Kazakhstan cities – 2020» environmental project that engages essentially the water industry and that is being implemented nowadays is presented. The timeliness of the project comes from the amendment of the national legislation, Article 301 of the Environmental Code of the Republic of Kazakhstan in particular (2016), that is related to the regulation of waste landfilling. The new regulatory document limits (and actually prohibits) storing dewatered wastewater sludge on landfills and prescribes to provide for its further processing with the purpose of transferring theses wastes from «hazardous organic wastes» category to recultivants, cultivation soil etc. The project envisages the use of Russian technology of wastewater sludge dewatering on sludge beds with the use of «Sibflok®» flocculant and the technology of enhanced composting of organic wastes developed by the experts of International Academy of Ecology (Astana). The implementation of this project will provide not only for reducing significantly the amount of municipal sludge transported to landfilling but also for establishing the production of soil-like substrates, soils for remediation of desertificated territories, landfills, dumps; and in case of advanced processing – for urban greening services.

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№11|2014

WASTEWATER SLUDGE TREATMENT

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UDC 628.336.57

KOZLOV M. N., Bogomolov M. V., Kevbrina M. V., Agaryov A. M.

The efficiency of enhancing wastewater sludge digestion

Summary

The results of experimental studies of enhancing wastewater sludge digestion as applied to the process flow scheme of the Kur’ianovskie Wastewater Treatment Facilities are presented. The specialists of the R&D Centre of «Mosvodokanal» JSC tested in the laboratory and calculated the economic efficiency of three options of digestion enhancement: sludge processing in the process of thermal hydrolysis before digestion; increasing the hydraulic retention time; increasing the solids retention time. The studies were aiming at comparing the efficiency of sludge digestion when using the given technology solutions. Increasing the hydraulic retention time (HRT) is caused by sludge thickening enhancement before digesters. The experience of the Prague wastewater treatment facilities shows that thickening enhancement alone provides for efficiency improving by a few percent. This was confirmed in the process of laboratory experiments in the R&D Centre. Sludge pretreatment before digestion with the purpose of accelerating the hydrolysis of stable organic matter, e. g. thermal hydrolysis, ensures significant enhancement of the entire process by activating the slowest stage of hydrolysis; as a result, the decomposition of ash-free matter and biogas output were increased by 10–30%. However, this type of technology involves high capital expenditures. Increasing the solids retention time (SRT) is achieved by retaining solids in the digester while maintaining the hydraulic retention time (HRT). This can be ensured by retaining or recycling solids to the digester. The technology of sludge recycling serves as an example that provides for the high organic matter decomposition by means of increasing the solids retention time without any significant capital investments. Thus, following the results of the studies the given technology has been accepted as a most cost-effective.

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Российская ассоциация водоснабжения и водоотведения

Конференция итог

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