Constructed wetlands have the ability to accumulate and retain organic substances. The accumulation of these substances is the result of excess of the primary production in relation to the respiration of heterotrophic microorganisms active in the wetland system [www.ekologia24. biz25.05.2014, Ozimek et al. 1996]. Organic matter produced in the environment of wetland

Abstract. The aim of the study was to compare the composition of wastewater from the facility producing fruit and vegetable juices and dairy processing plant in Podlasie province. Their composition is also influenced by processes of washing and disinfecting of production lines. The washing process moves solid, colloidal, and dissolved impurities to the wastewater, depending on the type of raw material processed and the technological process used. At the same time, cleaning and disinfecting components at the amounts difficult to determine, penetrate the wastewater. The seasonal oscillations in the quantity and quality of sewage composition originating from fruit-vegetable and dairy processing became a problem for many conventional wastewater treatment plants, to where they are discharged. Based on the survey, it was found that wastewater from the fruit and vegetable industry as well as dairy industry contained large amounts of organic matter expressed in BOD 5 (fruits and vegetables processing from 860 to 3 200mg O 2 /dm 3 , dairy from 1 410 to 3 850 mgO 2 /dm 3 ) and COD (fruits and vegetables processing from 919 to 3 700 mgO 2 /dm 3 , dairy from 1 680 to 5 420 mgO 2 /dm 3 ). Significant differences were found in concentrations of nitrogen and phosphorus in compared raw wastewater.

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The study aimed to assess the most efficient solution of raw material management in selected biogas plants into the concept of circular economy and evaluate the most efficient solution of raw material management in selected biogas plants due to the quality and quantity of the feed and the final product obtained, which is biogas, as well at the closed circulation (circular economy). The study evaluated two agricultural biogas plants on a real scale and one at the sewage treatment plant (in real scale) in northeastern Poland. A year-long study showed that in technical terms, the best work efficiency is achieved by agricultural biogas plants processing: silage, manure, apple pomace, potato pulp (biogas plant No. 1), followed by biogas plant No. 3 processing chicken manure, decoction, cattle manure, poultry slaughterhouse waste (sewage sludge, flotate, feathers), and finally, the lowest efficiency biogas plant was No. 2, the sewage treatment plant, which stabilized sewage sludge in the methane fermentation process. Moreover, based on the results, it was found that agricultural biogas gives the best efficiency in energy production from 1 ton of feed.

The purpose of the work was to determine the effectiveness of wastewater treatment from the fruit and vegetable industry in constructed wetlands supported by a bio-preparation. An increase in the efficiency of organic substance purification expressed as BOD5 and COD by 8% in deposit with the addition of bio-preparation in relation to the control bed (without the addition of bio-preparation), was found. The efficiency of the total suspension, total nitrogen and total phosphorus increased respectively by 19.5%, 10%, and 27% in relation to the bed without addition of biopreparation. Constructed wetlands treatment plant ensures high removal of organic compounds expressed as BOD5 and COD, as well as guarantees reduction in the concentration of nitrogen and phosphorus compounds.