Evaluation of mineralization rates of biosolids from domestic wastewater treatment plants

The biosolids from wastewater treatment plants have high potential of agricultural application due to the contents of organic matter and nutrients. The mineralization of biosolids from the Canaveralejo Wastewater Treatment Plant, Cali-Colombia, was evaluated by fitting regression models. The content of NH4+, NO3- and NO2- were monitored during 126 days for three types of biosolids: dehydrated, thermally dried and alkalinized, which were applied to a Vertic Endoaquepts soil using doses of 35.4, 36.4 and 54.5 t ha(-1) respectively. To adjust the regression curves, the models used were: simple exponential, double exponential, hyperbolic, parabolic and some regular statistical models. The results showed that the parabolic model proposed by Broadbent presented the best fit to describe the process of mineralization in the evaluated soil. The exponential model of Stanford & Smith was the second option of modeling, permitting corroborate the increase of organic nitrogen (N-0) when the biosolids are applied and the mineralization increase in relation to the control treatment.