Towards the new era of sewage sludge management in China: Status, challenges, and perspectives

Increasing sludge has posed great challenges to the environment and thus necessitates more sustainable disposal. Sludge valorization technologies are very promising pathways in the era of emphasizing sustainable development, which can realize the harmless treatment of sludge and value-added products recycling simultaneously. This paper statistically analyzed the development trend of sewage sludge production, treatment capacities and geographical distribution in China during recent years. The status quo of sludge valorization technologies was reviewed from the perspectives of development status, project operation, distribution, and application scale. Results showed that municipal sludge production accounted for most of the total sludge production in China. There is a geographical imbalance in the sewage sludge treatment capacity, showing a trend that the eastern part was higher than the western regions. Anaerobic digestion + land application (15.55 %), composting + land application (9.61 %), incineration + landfill/building materials application (65.41 %) and deep dewatering + landfill are four major sludge disposal technical routes in China. Carbonization as a new direction for sludge recycling has also been applied on a small scale (<300 t/day). The domestic and foreign management policies on sewage sludge were reviewed and compared. At present, the harmless disposal rate of sludge in China is around 70 %. Although great progress has been made in sludge treatment and disposal, there is still a distance from the target of harmless disposal (90 %). The development of sludge industry still faces many challenges in technical and policy aspects. These challenges and initiatives to overcome the difficulties were presented in detail. To address these issues, decision-making frameworks for selecting sludge treatment and disposal routes have been developed, offering valuable guidance for industries, countries, and regions facing similar dilemma.