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The purpose of this research was to prove that a hybrid system including activated sludge and biofilm attached to carrying media (natural zeolite) can improve the efficiency of municipal wastewater treatment. The study was performed using a pilotscale plant installed on Almaty Wastewater Treatment Plant (Kazakhstan) and treated sewage after preliminary mechanical treatment. The investigations were conducted in 2 stages: with installation without packing media (activated sludge only) and packed with zeolite from Chankanaysky field (activated sludge and biofilm). The results from the study showed a significant improvement of treatment efficiency for all examined parameters (BOD 5 , COD, suspended solids, nitrogen compounds and phosphates). Microbiological examination of biomass from the bioreactor indicated high diversity and activity of identified species, proving good conditions for both activated sludge and biofilm.

Sediments constitute one of the wastes that are generated in sewage treatment plants. The methods of their final management depend on the sewage sludge system management. One of the employed methods is Autothermal Thermophilic Aerobic Digestion (ATAD). The article presents the process of autothermal oxygen digestion of sewage sludge as a method enabling to obtain biomass, which can be used in the natural environment. In addition to the description of the theoretical basis of the discussed process, the quality of the formed sewage sludge is presented. The amount of sludge and the manner of its final utilisation were also analyzed. The results were presented on the basis of waste records kept in each of the analyzed sewage treatment plants. Sludge transfer cards in 2013-2018 were also analyzed in the sewage treatment plants where sludge undergoes the ATAD process.

The article aimed to analyze the concept of modernisation of sludge management prepared for an exemplary sewage sludge treatment plant. Four variants of solutions, based on different processes, aerobic (oxygenic), anaerobic or – aerobic – anaerobic, were discussed. The article presents the characteristics of essential elements of the proposed solutions. The technical and technological parameters of each of the variants are exposed. The expected capital expenditure and basic operating costs are presented. A cost-effectiveness analysis of the options has also been carried out. The analysed technological processes ensure obtaining hygienically and sanitary safe end products. They contribute significantly to minimising the amount of sewage sludge. The most economically efficient, with the lowest average annual costs, is the variant with the application of anaerobic thermo-philic-mesophilic sludge stabilisation. The highest average annual costs were obtained for the variant with drying and incineration of sludge.