Evaluation of heavy metal content and physicochemical parameters in sludge from the wastewater treatment plant of the city of Celendín-Cajamarca

Abstract

The main objective of this research work was to determine the quality of the sludge from the WWTP of the city of Celendín, in response to the D.S. 015-2017-Housing, which establishes maximum values in different physical, chemical and biological parameters, so that this organic material can be used in the fertilization and improvement of soils; Within this, the concentration of the metalloid arsenic and the heavy metals Cd, Cr, Cu, Pb, Ni and Zn, pH, and organic matter were determined; presence of E. coli, Salmonella and helminth eggs; as well as total nitrogen; Likewise, other parameters were evaluated such as calcium carbonates, electrical conductivity, and other nutritional elements such as phosphorus and potassium; with the purpose of determining the level of toxicity of the biosolid, fertilizer potential and sanitation, considering its fertilizer and soil improver potential. The average results obtained for the different parameters were as follows: pH (7,2), organic matter (20 %), electrical conductivity (393,5 mS/m), calcium carbonates (14,6 %); Regarding the concentrations of heavy metals found in the sludge, it was as follows: Arsenic (1,54 m.kg^-1), cadmium (1,79 m.kg^-1), chromium 22,41 m.kg^-1, copper (61,28 m.kg^-1), nickel (8,6 m.kg^-1), lead (17,93 m.kg^-1), zinc (602,52 m.kg^-1); E. coli (383,95 NMP/1gST), Salmonella sp (1,144 NMP/1gST) and helminth eggs (zero). These sludge analysis results were evaluated and interpreted in accordance with current national regulations D.S. 015-2017-Housing, where it is seen that the average value of Salmonella sp (1,144 NMP/1gST), slightly exceeds the value of the regulations (1 NMP/10 g total solids); concluding that the sludge is classified as biosolid A, being suitable for use in agriculture and/or soil improvement; It should also be noted that the sludge from the Celendín WWTP contains satisfactory levels of the macronutrients nitrogen, phosphorus and potassium, being appropriate for use as a physical, chemical and biological improver of agricultural soils.