State Unitary Enterprise `Vodokanal of St. Petersburg`
Vodokanal St. Petersburg provides high-quality water and wastewater services to the customers taking care of the environment and creating a responsible attitude to water resources. IT supplies potable water to the citizens - over 5,000,000 people, and to the city companies and organizations.
Vodokanal provides wastewater services to the citizens and companies: the volume of treated effluent was 816.266Mio. m3 in 2011. The length of sewer networks – 8245.58 km, the length of tunnel collectors – 232.17 km.
Moreover, Vodokanal operates the city fountains and fountain complexes; it is in charge of rehabilitation, capital repairs and operation of public toilets.
There are 9 waterworks (the biggest are Southern Waterworks, Northern Waterworks, Main Waterworks and Volkovskaya Waterworks) and 21 wastewater treatment plants (the biggest are Central WWTP, Northern WWTP and South-West WWTP) in St. Petersburg.
Vodokanal’s major achievements in water treatment:
- all potable water is UV treated before supply to the city to ensure epidemiological safety;
- no liquid chlorine is used for water disinfection, it is replaced by hazard-free, non-toxic sodium hypochlorite;
- hazard-free and non-toxic ammonia sulfate is used for water ammonization instead of ammonia solutions;
- a bio-monitoring system is used to check the Neva water quality where the crayfish are chief “inspectors”;
- PAC (powdered activated carbon) dosing system is implemented to remove odours and oil.
Vodokanal’s major achievements in wastewater treatment and disposal:
- Nearly 94% of all wastewater was treated in Petersburg at the end of 2011; by 2015, it is expected to reach a 98% level of treatment;
- Petersburg has found a solution to the sludge disposal problem: there are three sludge incineration plants in operation in the city;
- The treatment plants in Petersburg have implemented the enhanced nutrient (nitrogen and phosphorus) removal process to meet the HELCOM (the Baltic Marine Environment Protection Commission) requirements. It led to the reduction of biological load on the Neva, the Gulf of Finland and the Baltic Sea.
- Vodokanal has implemented a biomonitoring system to check the quality of treated effluent (the quality is evaluated by Australian red-claw crayfish) and the composition of flue gases emitted from one sludge incineration plant – by means of giant African snails.
Vodokanal activities are in compliance with:
- the General Plan of St. Petersburg,
- the General Water Supply Scheme and the General Wastewater Disposal (Sewerage) Scheme for St. Petersburg for the period till 2015 and in consideration of the perspective till 2025 (as approved by Act No. 1587 of the St. Petersburg Government dated 11.12.2007)
- the program of integrated development of public utilities infrastructure in St. Petersburg which covers electricity,-heat,-water supply; wastewater disposal and treatment for the period up to 2015 (approved by Act No. 1270 of the St. Petersburg Government dated 21.10.2008 as amended by the Order of the St. Petersburg Government “On Amending Act No. 1270 of the St. Petersburg Government Dated 21.10.2008' No. 1384 dated 30.11.2009);
- the Corporate Development Plan.
Provision of accessible water and sanitation services to ensure high quality of life for the customers and sustainable city development, to build the culture of water use and to preserve the Baltic Sea basin.
We see Vodokanal among the world’s best providers of water and sanitation services due to the quality of its services and environmental awareness.
- Responsibility before future generations – careful and efficient use of natural resources including water, energy, forests, etc.
- Responsibility before the customers – continuous studies of the customers’ expectations and requirements, improvement of customer interaction procedures to raise the level of satisfaction with the water and sanitation services.
- Responsibility before the staff – continuous improvement of labour safety, good salaries and wages, social security for the company employees and their families, and for the retired employees.
- Innovative approach – incorporation of international best practice in the company management, the use of advanced technologies and creation of know-how in different fields of activities – that is the only way to reach success and to be a leading company.
- Openness to the public and responsibility before the society – transparency of the company activities, access to reliable information on the company work and history, active interaction with the mass media, educational institutions, public and environmental organizations – all that constitutes the basis of our information policy.
In general, the water treatment process includes the following stages:
- water ammonation (ammonium sulfate is used),
- water disinfection (sodium hypochlorite is used),
- coagulation of pollutants (aluminium sulfate is used),
- flocculation (cationic flocculant is used)
- sand filtration in contact clarifiers (one-stage treatment scheme)
- sedimentation and sand filtration in rapid filters (two-stage treatment scheme)
- Disinfection by UV exposure.
Since 2007, Vodokanal applies a unique two-stage process of overall water disinfection at St. Petersburg waterworks.
This process is based on a highly effective but safe chemical – sodium hypochlorite (chemical method) and UV water treatment (physical method). Such combination enables us to fully guarantee epidemiological safety of water supply in St. Petersburg, and total compliance of microbiological indicators of water quality with the current norms.
Saint-Petersburg is the first megalopolis to treat all potable water with ultraviolet and to use no liquid chlorine for potable water disinfection.
The official ceremony of discarding the last chlorine container was held at the Northern Waterworks on 26 June, 2009. Chlorine (a hazardous substance to store and transport) gave place to safe sodium hypochlorite. Two plants for production of low-concentrated sodium hypochlorite are in operation in St. Petersburg – at the Southern Waterworks (since 2006) and at the Northern Waterworks (since 2008).
Another technology used by Vodokanal for over two years is a powdered activated carbon (PAC) dosing system which ensures removal of odors and oil products.
Vodokanal is proud of its unique system of water quality biomonitoring - diagnostics of the functional status of crayfish and fish.
The method developed by the Russian Academy of Sciences’ Environmental Safety Research Institute consists in measuring the local crayfish cardiorythm and analysing the behavior of fish. If the water from the Neva contains toxic substances, the heart rate of crayfish increases, and the behavior of fish changes significantly. Now, the biomonitoring system is used at all waterworks in the city.
The “staff” of the Main Waterworks includes 12 crayfish. Their working schedule: two days in the aquarium under supervision, then four days of rest and active eating. Vodokanal employs male crawfish only.
Wastewater treatment technologies
Until quite recently, at the wastewater treatment plants of St. Petersburg a classic, two-stage treatment process was used, comprising two main blocks:
- Mechanical treatment
- Biological treatment
Mechanical treatment is designed for wastewater clarification. This block comprises an inlet chamber, mechanized screens, grit channels and primary clarifiers.
The biological treatment block includes aeration tanks and secondary sedimentation tanks. The biological treatment process occurs due to vital activities of activated sludge in aeration tanks in continuous contact with atmospheric oxygen injected into the aeration tank. Activated sludge is a biocenosis inhabited by different bacteria, protozoa and multicellular microorganisms which transform contaminants in wastewater and treat them.