Natural wastes rich in terpenes and their relevance in the matrix of an on-farm biopurification system for the biodegradation of atrazine

A preliminary assay was performed to evaluate if natural wastes of low cost and rich in terpenes, such as pine needles, eucalyptus leaves and orange peels, added individually (5% w/w) into a microcosm simulating the matrix (peat based biomixture) of an on-farm biopurification system can be used to enhance the biodegradation of atrazine (ATZ) at 10 and 20 mg of active ingredient (a.i) of ATZ per kg of biomixture (mg a.i kg−1) and their enzyme activities. Accumulation of the degradation products deisopropylatrazine (DIA), deethylatrazine (DEA) and hydroxyatrazine (HA) were evaluated, and the volatile compounds emitted from the biomixture were also monitored. Addition of natural wastes allowed for a higher rate of biotransformation at both the ATZ concentrations evaluated. However, significant differences were observed with the addition of the orange peels (98%) and the eucalyptus leaves (95%) when compared to the control. ATZ biotransformation was not enhanced at either concentration when pine needles were added, but instead, this addition resulted in a decrease of the degradation efficiency compared with the control. The DIA, DEA and HA metabolites were detected in all treatments without clear formation patterns. Enzyme activities were negatively affected, especially following the addition of pine needles or eucalyptus leaves. However, the entire enzyme activities evaluated recovered quickly. In conclusion, the results obtained from this study demonstrated the relevance of using natural wastes rich in terpenes in a peat-based biomixture of a biopurification system to potentially enhance the ATZ biodegradation.