In recent years, there is already not achieved in Poland the acceptable costeffectiveness ratio of the construction of collecting systems and the rate of sewerage (collective and individual systems) is still low, especially in the countryside. Therefore it seems to be necessary to supplement the networks (sewerage) systems by individual treatment plants. In the article the choice of four variants of on-site wastewater treatment plant with soil absorption system using AHP analysis was presented and analysed. It has been shown that this method can be successfully used to select the variant of onsite wastewater treatment plant with soil absorption system. It should be taken into consideration which of two sub-criteria: system and receiver is a priority. It is also possible that both sub-criteria are equivalent. In the case of equivalent importance of system and receiver, domestic wastewater treatment plant with a pressurized soil absorption system was the most favourable, and the least favourable – septic tank with soil absorption system. In the variant of a “system” priority, domestic wastewater treatment plant with a pressurized soil absorption system prevailed over other variants but so little that from practical point of view also variants of septic tank with pressure and classic (gravitational) soil absorption system may be chosen. In the case of environmental factors priority a domestic wastewater treatment plant with a pressurized soil absorption system should be considered as the best one. The analyses carried based on certain attribute values confirmed earlier opinions on the important role of decision-makers’ experience or the usefulness of average values obtained from the analysis performed by several people.

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