Hidrológiai Közlöny 2006 (86. évfolyam)

3. szám - Kaposvári Kázmér: Description of the Szolnok municipal waste water treatmant plant based on the operation experiences of the 2000–2004 period

30 Description of the Szolnok municipal waste water treatment plant based on the operation experiences of the 2000-2004 period Kázmér Kaposvári Water and Sewage Works Franchising Joint Stock Company, 1 Vizmű str., 5000. Szolnok, Hungary Abstract: In September, 1999 there was a sewage purification plant with activated-sludge process and a capacity of 32000 m

3/d opened in Szolnok. It provides mechanical and biological cleaning from the received raw waste waters and the treated waste water is discharged into the current line of the Tisza River. The mechanical cleaning of the waste water is provided by revolving drum fine screens. The biological treatment comprises serially linked anaerobic, anoxic and oxic units. The separation of the contaminations to sludge and to treated water is carried out in Dorr type final settling basins. The composting process of the dewatered sludge is carried out in chamber type quick composting unit, chopped crop straw is used as C source. The composted sludge became a qualified product, which is completely used in the agriculture. The cleaning efficiency of the treatment plant is sufficient in respect of all the monitored parameters, and the cleaned waste water also satisfies the emission limits, waste water, water quality, Tisza River Keywords: Introduction The European Union promulgated the Water Frame Directive (2000/60/EC Directive) at the end of 2000 for the comprehensive protection of the ground and underground water reserves in respect of their volume and quality. The primary aim of the Frame Directive is the rehabilitation of the water catchment areas to bring them in to good ecological and chemical condition by 2015. One of the major elements of the Directive is the evaluation of the effects of point and diffuse emission sources on the waters. Regarding the point sources, one of the most important tasks is to trace and monitor the water quality variations due to the disposal of waste and utility waters into ground and underground reserves. The domestic regulations concerning the waste water disposals into ground waters were developed in order to satisfy the consolidation requirements of the legal frameworks of the member states after joining to the European Union. These are the 220/2004. (VII. 21.) Governmental decree for the protection of the ground waters, and the 28/2004. (XII. 25.) KvVM Ministerial decree containing the emission limits. According to the 7/2002. (III. 1.) KöM regulation the operating companies must conduct a self audit concerning their waste water emissions. The same procedure is applicable to the 32000 m

3/d dry period nominal capacity Szolnok municipal waste water treatment complex, which was inaugurated in 1999. Introduction to the Szolnok municipal waste water treatment and composting plant The treatment plant collects the waste waters from Szolnok city as well as from Rákóczifalva, Rákócziújfalu, Új szász, Zagyvarékas, Szászberek, Szajol, Tószeg, Tiszajenő, Tiszavárkony, Vezseny, Besenyszög settlements. The plant is equipped with a so called activated sludge treatment process. It provides mechanical and biological cleaning from the received raw waste waters. The treated water is discharged into the Tisza at the 331,757 river kilometer section. The waste water from the city and the surrounding settlements is collected by a 2200 mm dia trunk line which runs in 10 meters depth under the ground and directs the water to the final pumping station. The removal of the coarse debris is provided by a stone catcher and two 10 mm grid distance plane screens equipped with mechanical cleaning. The filtered waste water is transferred to the treatment plant by 4 pes Hidrostal type pumps through two 800 mm dia plastic underground pipelines. One of the pipelines directs the water to the cleaning process while the other bypasses the facilities and connects to the 1200 mm dia RCC pipeline discharging the treated water to the current line of the Tisza. The water directed to the treatment process is continuously measured and registered by an induction meter. The incoming water is flowing through the whole system up to the receiver by gravity. The additional mechanical cleaning of the waste water is provided by three 1.5 mm and one 2.0 mm dia perforation revolving drum fine screens. The filtered waste water is mixed with the recirculation sludge and directed to four parallel biological treatment lines through the distribution header. The biological treatment comprises serially linked anaerobic, anoxic and oxic environments. The two parallel lines are equipped with a common post-denitrification space and an after settler. The good contact between the activated sludge and the feed, as well as their constant flotation is provided by Flygt submersible mixers in the postdcnitrification spaces. The constant dissolved oxygen redundancy and the efficient mixing in the oxic spaces is provided by Flygt Sanitaire rubber membrane, fine bubble air blower units, for which the compressed air is supplied by rotary pumps. The anaerobic, the anoxic and the oxic spaces help the biological removal of phosphor, nitrogen, organic content and nitrogen contaminants respectively. The separation of the contaminations to sludge and to treated water is carried out in two 38,5 m dia Dorr type final settling basins. The biologically active sludge from the final settling basin reaches the sludge homogenizing unit where the material is mixed and pre-thickened. The excess sludge which is the byproduct of the cleaning process is blended with polymers to help the dewatering on the Humbold centrifuge and finally reaching a 20% dry substance level. As the result of waste water treating a significant amount of waste sludge forming is to be expected. The handling and storage of the sludge is expensive. At the Szolnok plant the sludge is not disposed as a waste since the sludge from the concentrator goes through the squeezers and comes to the store, from where it is transferred to the mixer and the fermentation chambers, and these units are all parts of the composting hall. This whole process takes place on the day of the compression. The composting process of the dewatered sludge is carried out in a 12500 t/year end product capacity, chamber type quick composting unit. In the Szolnok waste water treatment plant every units of the composting process (buildings, mechanical and electrical/automation elements) are located in one single