The Effect of Processed Sewage Sludge on the Growth and Accumulation of Nutrients and Pharmaceuticals in Maize Tissues in the Field Experiment

Sreynet Nang

Master's thesis

Abstract:

The rapid increasing of world population, urbanization, and industrialization resulting in significant increase of wastewater treatment plants and large quantities of sewage sludge production. Land application is generally considered as the most economical and beneficial way of sewage sludge disposal. Sewage sludge is nutrient-rich organic materials which can supply additional nutrients to soil and plants such as N, P , and in lesser extend K as well as other nutrients. Sewage sludge or biosolids were applied as fertilizer after drying and torrefaction (300 ◦C). Precise field experiment on Cambisol was set up in 8 treatments, each in 4 replications. Maize was grown on the soils with biosolids amended in two rates, control treatments with N or NPK application were also set up. During the vegetation period, maize aboveground biomass was harvested and analyzed for the concentration of nutrients N, P, K and pharmaceuticals. There were 44 pharmaceutical compounds detected in dried biosolids, however, after torrefaction the total pharmaceuticals contents in biosolids were reduced by 92.2 to 99.5%. In all treatments, pharmaceuticals were found below the detection limit in maize tissues at every harvest period. The accumulation of N, P, K were found with the highest concentration in maize tissues grown on the soil amended with dried biosolids compared to torrefied ones. However, except K ,there were no statistically significant differences of N and P accumulation among the treatments,. Based on our found results, soil amended with biosolid potentially increased the maize yields as well. This study showed that torrefaction had the ability to remove pharmaceuticals in high amounts, minimize further uptake of pharmaceuticals by plants, and increase aboveground biomass production. Nonetheless, similar to the use of the commercial fertilizers, biosolids could serve as an acceptable source of plant nutrients.

Keywords

Sewage Sludge, Thermal Treatment, Field Experiment, Maize

Language used: English

Date on which the thesis was submitted / produced: 26. 4. 2021

Thesis defence

• Supervisor: prof. Ing. Pavel Tlustoš, CSc. dr. h. c.

Czech University of Life Sciences Prague

Faculty of Agrobiology, Food and Natural Resources

Master programme / field:
Natural Resources and Environment / Natural Resources and Environment