This review aimed to analyse the current state of management practices for poultry manure in Poland and present future perspectives in terms of technologies allowing closing the loops for circular economy, and thus recovery of nutrients and energy. The scope of the review focused primarily on: (1) the analysis of poultry production and generation of poultry manure with special references to quantities, properties (e.g. fertilizing properties), seasonality, etc.; (2) the overview of current practices and methods for managing poultry manure including advantages and limitations; (3) the analysis of potential and realistic threats and risk related to managing poultry manure, and also (4) the analysis of promising technologies for converting poultry manure into added value products and energy. The review addressed the following technologies: composting of poultry manure to obtain fertilizers and soil improvers, anaerobic digestion of poultry manure for energy recovery, and also pyrolysis of poultry manure into different types of biochar that can be applied in agriculture, horticulture and industry. Poultry manure is rich in macro- and micronutrients but also can contain various contaminants such as antibiotics or pesticides, and thus posing a realistic threat to soil and living organisms when applied to soil directly or after biological treatment. The main challenge in poultry manure processing is to assure sufficient closing of carbon, nitrogen and phosphorous loops and safe application to soil.

The urban wastewater treatment plants can be an important part of circular sustainability due to integration of energy production and resource recovery during clean water production. Currently the main drivers for developing wastewater industry are global nutrient needs and water and energy recovery from wastewater. The article presents current trends in wastewater treatment plants development based on Circular Economy assumptions, challenges and barriers which prevent the implementation of the CE and Smart Cities concept with WWTPs as an important player. WWTPs in the near future are to become “ecologically sustainable” technological systems and a very important nexus in SMART cities.