Natural treatment of domestic wastewater and desert soil restoration
using green soil amendments
Abstract
This study evaluated the combination effect of soil amendments with
sandy soil on wastewater contaminants removal, and the ultimate impact
on soil restoration. A soil column experiment was conducted with sandy
soil (CK) or soil amended with 4% (w/w) compost, biochar or maize
straw. Wastewater infiltration was recorded, and alfalfa was planted
subsequently. Results showed that amendment of biochar and straw
significantly decreased domestic wastewater infiltration rate in sandy
soil, with a reduction of 62 and 50% compared to CK. All combination of
soil and amendments had removal ability for wastewater contaminants, as
indicated by the sorption capacity and the resist for desorption. The
largest sorption capacity was found in biochar-amended soil. Plant and
soil microbes also played important role in contaminants removal. The
amendment of biochar and compost significantly improved plant growth,
microbial abundance and diversity. The plant biomass of compost and
biochar treatments was 3.8 and 4.6 folds of CK. After plant harvest,
straw and compost treated soil had increased soil aggregates compared to
CK. It is concluded that sandy soil-organic amendments-plant system
could be used as an efficient wastewater treatment strategy for nutrient
and pathogen removal. Moreover, wastewater input and plant cultivation
could improve structure of the coarse-sandy soil.