ABSTRACT
Sewage sludge is a consequence of wastewater treatment that is produced in vast amounts all over the world, posing the responsibility of properly handling organic waste. The two primary disposal techniques for municipal sewage sludge management are reuse, which includes agricultural or landscaping applications, and ultimate disposal. Because there are a variety of concerns with final disposal techniques across the world, preparing sewage sludge for reuse, also known as sludge processing, provides another option. The goal of this review paper was to investigate sludge management strategies throughout the world and highlight its use in the agricultural sector in developing nations like India. The use of sewage sludge as a fertilizer is ecologically beneficial and results in the reuse of potentially hazardous wastes, in addition to contributing in waste reduction. The quantity of heavy metals, on the other hand, is the most significant criteria for the safe use of sewage sludge in agriculture, followed by pathogen reduction. If sewage sludge is correctly processed with appropriate technology, it has the potential to lessen our dependency on chemical fertilizers and so fall within the scope of our government’s ’waste to wealth’ initiative.
Keywords: Sludge, Agriculture, Technology, Management practices, Fertilizer
Introduction
Sewage sludge is a byproduct of wastewater treatment that is mass-produced all over the world. Municipal sewage sludge is generally termed as sewage sludge which is produced after the municipal wastewater treatment process. It contains organic and inorganic components, as well as a high concentration of nutrients, organic compounds, and pathogenic organisms. Therefore, proper treatment of the sludge is critically important in order to reduce the sludge’s environmental impact. This organic waste must be carefully managed due to massive sewage sludge production all over the world. For the complete and suitable management of the municipal sewage is mainly depend on the two strategies, one is its reuse for agriculture or landscaping and second is the final disposal. There are several ways for reusing sewage sludge, but there are also many limitations to using a particular management strategy (Kacprzak et al., 2017). The recovery, or recycling or recovery of organic compounds, is the most essential notion linked with the transformation of sewage sludge (Petric et al., 2022). The global population is growing and condensing in metropolitan areas and this trend is especially pronounced in emerging nations and as per the United Nation (2012) reports, an extra 2.1 billion people are predicted to live in cities by 2030 (Martin, 2012).
Every year, urban cities generate billions of tonnes of trash, including sludge and wastewater. These wastes can have a variety of outcomes depending on the local context: they can be collected or not, treated or not, and eventually used directly, indirectly, or not at all. With few and partial exceptions, data on these waste streams is rare and dispersed in the literature, and thorough studies and analyses at the global level are lacking. However, recent initiatives by global organizations such as the FAO/IWMI through AQUASTAT, UN-Habitat (2008), and the Global Water Intelligence (GWI 2014) have allowed these evaluations to be renewed and updated (Mateo-Sagasta, 2015; Gude, 2016).
Water, organic matter, energy, and nutrients (e.g., nitrogen and phosphorus) are all significant resources in municipal wastewater and sludge that may be recovered for a variety of economic, social, and environmental objectives. Sludge / sewage sludge is created when suspended particles are removed from wastewater and soluble organic compounds are transformed to bacterial biomass, which is then added to the sludge (Figure 1).