Agricultural and non-agricultural directions of bio-based sewage sludge valorization by chemical conditioning

Abstract

This literature review outlines the most important—agricultural and non-agricultural—types of sewage sludge management. The potential of waste sludge protein hydrolysates obtained by chemical sludge conditioning was reported. The discussed areas include acidic and alkaline hydrolysis, lime conditioning, polyelectrolyte dewatering and other supporting techniques such as ultrasounds, microwave or thermal methods. The legislative aspects related to the indication of the development method and admission to various applications based on specified criteria were discussed. Particular attention was devoted to the legally regulated content of toxic elements: cadmium, lead, nickel, mercury, chromium and microelements that may be toxic: copper and zinc. Various methods of extracting valuable proteins from sewage sludge have been proposed: chemical, physical and enzymatic. While developing the process concept, you need to consider extraction efficiency (time, temperature, humidity, pH), drainage efficiency of post-extraction residues and directions of their management. The final process optimization is crucial. Despite the development of assumptions for various technologies, excess sewage sludge remains a big problem for sewage treatment plants. The high costs of enzymatic hydrolysis, thermal hydrolysis and ultrasonic methods and the need for a neutralizing agent in acid solubilization limit the rapid implementation of these processes in industrial practice. Graphical abstract

Economic and Technological Principles of Safe Use of Sewage Sludge in Agriculture

“…Том 24, Вип. 2 (83) 141 (Izydorczyk et al, 2021). In this respect, the environmental impact of SS in case of landfill disposal, agricultural use or other applications is of great importance.…”

“…It is worth mentioning that stabilization is a biological process. On the other hand, the law imposes restrictions on sludge disposal in landfills, which applies to sludge containing > 5% organic matter (Boehler and Siegrist, 2006) (Izydorczyk et al, 2021).…”

“…Hydrolysis at elevated temperatures shortens the chains of macromolecular organic compounds (for methanogenesis), leads to the dehydration and hygienization of the SS (Xu et al, 2019) (Izydorczyk et al, 2021). Thermal pretreatment includes high (usually between 150 and 250 °C) and low temperature (60-100 °C) thermal hydrolysis, which means increased sludge temperature, usually induced by hot steam (Pilli et al, 2015) (Izydorczyk et al, 2021). The SS treatment at 140-170 °C, 5-35min contact time and single sudden decompression was reported as optimum (Sapkaite et al, 2017).…”

Application of Advanced Oxidation Technology in Sludge Conditioning and Dewatering: A Critical Review

“…Sludge treatment has become a key challenge for the Chinese water industry [ 2 ]. Sludge has the characteristics of high-water content, large volume, and high treatment cost, showing the performance of the fluid or semi-fluid state, causing great inconvenience for subsequent transportation and treatment [ 3 ].…”

Estabilización alcalina de lodos de PTARD para obtener biosólido tipo A

“…El tratamiento de alcalinización de lodos de planta de tratamiento de aguas residuales busca obtener una materia prima secundaria útil y reducir el daño ambiental, es necesaria una evaluación de las propiedades higiénicas y sanitarias de los lodos (Izydorczyk et al, 2021). Por consiguiente, el objetivo del estudio fue evaluar el efecto alcalinizante de la cal viva, cal de baja ley y polvillo de los filtros en los lodos obtenidos de la planta de tratamiento de aguas residuales (PTARD); se evaluaron los parámetros fisicoquímicos, toxicidad química y estabilización del proceso de alcalinización de lodos de la planta de tratamiento de aguas residuales (PTARD).…”