This paper presents an analysis of the literature that studies the possibility of sewage sludge being used in the cement industry to reduce carbon dioxide emissions from cement production and thus solve the problem of disposing of sewage sludge so that it is no longer stored, avoiding soil pollution with heavy metals, and reducing pressure on the environment. The ash of sewage sludge is a good pozzolanic material, because when it is finely ground, it can be used as a partial substitute for Portland cement. This reduces waste storage costs. Sewage sludge ash was mixed with cement, and it was analyzed to determine whether the paste obtained could be used as a raw material in the cement industry. The presented results are on the hydration characteristics of the sewage sludge ash, the compressive strength of the cement determined after different days, the workability of the cement, and the porosity of the cement paste and the ash.

Considering that worldwide the amount of sludge from sewage treatment plants has increased, which through storage pollutes the environment, solutions must be found for its management. In this paper, through an analysis of studies from the literature, we present an ecological method of recovery of sewage sludge (SS) in agriculture through vermicomposting with Eisenia etida, Eisenia andrei, Eudrilus eugeniae and Perionyx excavatus earthworms, thus we analyzed the possibility that sewage sludge can be transformed from waste into quality fertilizer that benefits the soil, plants, and people, thus being able to replace chemical fertilizers which, if applied to the soil, can acidify and pollute the soil and agricultural crops. We observed that the total nitrogen content of the phosphorus increased. Through the vermicomposting process, organic substances are rapidly decomposed and nitrogen mineralization is accelerated. We studied the impact of dewatered sewage sludge vermicomposting on pH value, electrical conductivity, porosity, moisture content, nitrogen content, water retention capacity, metal content, and the development of agricultural crops, highlighting the positive impact of vermicompost application on the soil. Adding vermicompost to the soil has been observed to improve plant development.