Hydrothermal Carbonization and Pyrolysis of Sewage Sludge: Effects on Lolium perenne Germination and Growth

Abstract

The pyrolysis and hydrothermal carbonization (HTC) of sewage sludge (SS) resulted in products free of pathogens, with the potential for being used as soil amendment. With this work, we evaluated the impact of dry pyrolysis-treated (600 °C, 1 h) and HTC-treated (200 °C, 260 °C; 0.5 h, 3 h) SS on the germination, survival, and growth of Lolium perenne during an 80 day greenhouse experiment. Therefore, the hydrochars and pyrochars were amended to a Calcic Cambisol at doses of 5 and 25 t ha−1. The addition of sludge pyrochars to the Cambisol did not affect Lolium germination, survival rates or plant yields. However, the use 25 t ha−1 of wood biochar reduced germination and survival rates, which may be related to the low N availability of this sample. In comparison to the control, higher or equal plant biomass was produced in the hydrochar-amended pots, even though some hydrochars decreased plant germination and survival rates. Among all the evaluated char properties, only the organic and inorganic N contents of the chars, along with their organic C values, positively correlated with total and shoot biomass production. Our work demonstrates the N fertilization potential of the hydrochar produced at low temperature, whereas the hydrochar produced at 260 °C and the pyrochars were less efficient with respect to plant yields.

Assessing the Effects of Biochar on the Immobilization of Trace Elements and Plant Development in a Naturally Contaminated Soil

“…Nevertheless, Solaiman et al [57] reported increases, no changes and decreases in plant germination after the application of five different biochars. Paneque et al [58] also showed no differences in germination with the application of biochars from sewage sludge to a Calcic Cambisol.…”

Effects of Biochar and Ground Magnesium Limestone Application, with or without Bio-Fertilizer Addition, on Biochemical Properties of an Acid Sulfate Soil and Rice Yield

“…It is known that the application of biochar at the rate of 15 t ha −1 not only increase soil water holding capacity, but also enhance plant growth. It means that due to biochar application water use efficiency for crop production is improved [22,23]. Furthermore, biochar has been known to increase the yield of cowpea [24], soybean [25], maize [26] and upland rice [27].…”

Effects of Sewage Sludge Amendments on the Growth and Physiology of Sweet Basil

“…This indicates that SS amendment induced only quantitative changes in basil plants and not qualitative ones, with positive effects on plant growth. Similarly, previous research has shown a positive correlation between organic and inorganic N from SS and shoot biomass of ryegrass Lolium perenne L. [64]. The addition of 15% SS to ES may represent a feasible alternative for SS reuse as important amounts of SS can be thus disposed with positive effects on soil properties and plant yields.…”