Agroecological assessment of sludge from wastewater treatment plants in the aim of their use in the practice
Vessela Georgieva, Svetla Marinova, Rositsa Georgieva, Daniela Stankova, Ginka Paunova, Yordan Tachev
Abstract: Sludge is an environmental problem, as it accumulates in the area of treatment plants, hindering their functioning and pollute the environment. At the same time, due to the shortage of organic sources in our country, sludge is a rich organic reserve due to the organic matter, macro and microelements contained in them. The aim of the study is to make an agroecological assessment of sludge, including agrochemical, chemical and microbiological characteristics of 5 WWTP’s sludge. Verified international standardized methods as well as validated internal laboratory methods are applied.
The conducted studies of sludge from the surveyed five wastewater treatment plants (WWTP) show that in terms of chemical and agrochemical characteristics they are biomass, rich in organic matter and nutrients. The values of heavy metals in the studied batches of sludge, compared to the maximum permissible concentrations (MPC) in the normative documents, are lower and do not limit the use of sludge in agricultural practice. Sanitary and microbiological tests have shown that in some of the sludge self-cleaning and decontamination has occurred, and in others the indicator microorganisms are in quantities higher than required. This is an indication that more residence time or appropriate treatment is needed so that they can be used in practice without posing a health risk to humans.
Summarized, with proper management of WWTP sludge, after conducting chemical, agrochemical and biological studies in accordance with the requirements of the legislation, they can be used as an appropriate soil improver without environmental pollution in agriculture and forestry, for reclamation of disturbed terrains, etc. In each individual case it is necessary to develop a specific technological project.
The conducted studies of sludge from the surveyed five wastewater treatment plants (WWTP) show that in terms of chemical and agrochemical characteristics they are biomass, rich in organic matter and nutrients. The values of heavy metals in the studied batches of sludge, compared to the maximum permissible concentrations (MPC) in the normative documents, are lower and do not limit the use of sludge in agricultural practice. Sanitary and microbiological tests have shown that in some of the sludge self-cleaning and decontamination has occurred, and in others the indicator microorganisms are in quantities higher than required. This is an indication that more residence time or appropriate treatment is needed so that they can be used in practice without posing a health risk to humans.
Summarized, with proper management of WWTP sludge, after conducting chemical, agrochemical and biological studies in accordance with the requirements of the legislation, they can be used as an appropriate soil improver without environmental pollution in agriculture and forestry, for reclamation of disturbed terrains, etc. In each individual case it is necessary to develop a specific technological project.
Keywords: characteristics; practical use; WWTPs sludge
Date published: 2022-03-21
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