The new urban waste water treatment plant located in the suburbs of Pavlikeni is gradually gearing up and deploying its full potential as time progresses in compliance with technological requirements.
This is a repost of Новата пречиствателна станция подобри околната среда в Павликени, България, originally published by Georgi Bachvarov (Facebook), and submitted to the Europe in My Region 2016 blogging competition.
About ten months ago the production of treated water started with a 3-hour operating cycle over 24 hours. Gradually, as water and sediments accumulated in the tanks, the operating cycle was increased to 4 hours, 8 hours and, more recently, 12 hours. Now all the equipment operates 24 hours per day.
The Pavlikeni urban waste water treatment plant was commissioned in October 2015. The facility is the most extensive infrastructure project in the history of Pavlikeni.
The project entitled “Construction of an urban waste water treatment plant with a head collector and their adjoining infrastructure in the town of Pavlikeni” was financed under the Cohesion Fund of the European Union and the State budget of the Republic of Bulgaria under the “Environment 2007—2013” Operational Programme. The total amount of the project is BGN 30,979,121, of which only 3%, i.e. BGN 776 327, was co-funded by the Municipality of Pavlikeni.
Ten months after it was commissioned, we visited the urban waste water treatment plant and met its Manager, Chemical Engineer Todor Papazov, to find out how it works and who operates and maintains it.
Waste water from the the entire area covered by planning regulations in Pavlikeni is collected in the treatment plant, where it goes through several stages of treatment: water from production facilities, domestic waste water and sewage, rain water and water from the Pavlikenska river. Water is brought to the treatment plant by means of drains and collectors. In the urban treatment plant, water goes first through a unit for removing large-sized waste such as plastic bottles, branches, leaves, pieces of plastic, etc. The liquid then passes through a coarse grid and the waste is discarded in a special container. Here there is a risk of flammable and explosive methane gas accumulating due to extensive putrefaction processes. Accordingly this area is equipped with a fire alarm system.
After primary mechanical purification, the water is transferred to the next production room by means of powerful pumps. Here two units operate separately or jointly depending on the quantity of input water. Due to the dry autumn, only one of these units is currently operating. Here the water undergoes a few more procedures in various mechanisms for two mechanical treatments: to eliminate large particles such as sand, etc., and then impurities such as oils, detergents and fine particles. Here waste pollutants are also discarded in special containers.
After undergoing three types of mechanical purification, the water enters a selector, where the liquid is homogenised by means of a huge mixer. It then flows into the primary organic treatment basin, a huge cylindrical unit, the biggest in the whole production complex in the waste treatment plant. It has a capacity of 2000 cubic metres of water. Here there are 50 tonnes of active sediments: micro-organisms which feed on what is left after the mechanical wastewater treatment, further purifying it. There are two zones here: an aerobic zone, in which oxygen is constantly introduced by means of 3 powerful aerators, and an anaerobic zone free of oxygen. This basin, as well as all other units, are duplicated in accordance with the latest requirements for the construction and operation of this kind of environmental installation.
The treated water must comply with specific acidity, alkalinity, nitrogen, phosphorous and oxygen content requirements. The treated water is returned to the bed of the Pavlikenska river and the separated sediment from the secondary organic treatment basin, after accumulating in sufficient quantities, undergoes various procedures such as dehydration and decontamination, after which it is compacted and used as fertiliser.
At the waste treatment plant water intake and outfall, delivery flow meters measure the amount of processed water. Currently about 3000 m³ pass through the plant in 12 hours, says the Manager of the waste treatment plant, Chemical Engineer Todor Papazov. A curious fact is that there is also an ultraviolet lamp at the water outfall from the plant. In the event of an outbreak of cholera, plague or similar dangerous disease, the water here will be treated with ultraviolet light to kill all pathogenic organisms. Fortunately, for the time being no such hazards have been declared in Bulgaria and facilities of this kind, if available, have never been used.
The whole production cycle can be operated electronically and manually. The duty operator monitors the process on two display units in the waste treatment plant control room. The plant also has a chemical laboratory for testing water samples. Samples are taken regularly during the day at the water intake and outfall at precisely specified locations. The chemical laboratory has the most up to date equipment, says laboratory assistant Imran Alieva. She is a qualified chemist specialised in water technology. The chemical and physical-chemical properties of the samples are recorded in a special log book, which is shown to the plant manager, who reports daily to the training instructor in Sofia.
The wastewater treatment plant also has a powerful 20 KV diesel generator. In the event of a power cut, the generator cuts in automatically after three seconds, ensuring a continuous production process. It has been activated three or four times since the plant was commissioned.
The eight members of the team of the Pavlikeni urban waste water treatment plant have undergone initial training on location, but they are continuing to learn the details of how to manage such a complex and up-to-date facility. In parallel with this, in the warm autumn period here they are working hard on cultivating the adjoining area and turning it into a really attractive environmental location, planting saplings, decorative shrubs, bulbs and generously extending this invitation to their guests: “Come here in the spring, when the tulips and hyacinths turn into blossom…”