Wastewater effects on montmorillonite suspensions and hydraulic properties of sandy soils

Journal Article · Tue Jun 01 04:00:00 EDT 1999 · Soil Science Society of America Journal

DOI:https://doi.org/10.2136/sssaj1999.03615995006300030018x· OSTI ID:20006696

Tarchitzky, J; Golobati, Y; Keren, R; Chen, Y

Recycled wastewater effluent is an important source of irrigation water in arid and semiarid regions. In these regions, however, irrigation water quality is one of the main factors limiting plant growth. Wastewater effluents generally contain high concentrations of suspended and dissolved solids, both organic and inorganic. Inorganic dissolved solids are only minimally removed from the effluent during conventional sewage treatment. As a result, most of the salts added during domestic and industrial usage remain in the irrigation water and may eventually reach the soil. A number of researchers have reported reduced hydraulic conductivity for soils to which treated wastewater has been applied. In this research, the influence of dissolved organic matter (DOM) contained in reclaimed wastewater effluents on the flocculation of montmorillonite and on the hydraulic properties of soils was studied. Flocculation values (FVs) for Na-montmorillonite increased with increasing concentrations of DOM at all pH levels analyzed. Maximum FV levels were exhibited for Na-montmorillonite at the highest DOM concentrations. The effect of DOM on FV can be explained by the mechanisms of edge-charge reversal and mutual flocculation. The hydraulic conductivity (HC) of a sandy soil was determined in the laboratory by leaching columns with an electrolyte solution chemically similar to that of the wastewater effluent (but without DOM). In columns treated with wastewater effluent, the HC exhibited a sharp decrease to only 20% of its initial value. The adverse effect of DOM on HC was evident for this soil despite a relatively low exchangeable sodium percentage (ESP). The reduction in HC is likely to be the result of decreases soil pore-size, which reflects two processes: (1) retention of part of the DOM during water percolation; and (2) a change in pore-size distribution due to swelling and dispersion of clay particles. The latter may result from a higher percentage of adsorbed sodium combined with the presence of humic substances from the wastewater effluent.

• Research Organization: Ministry of Agriculture, Tel-Aviv (IL)
• OSTI ID: 20006696
• Journal Information: Soil Science Society of America Journal, Journal Name: Soil Science Society of America Journal Journal Issue: 3 Vol. 63; ISSN 0361-5995; ISSN SSSJD4
• Country of Publication: United States
• Language: English

Related Subjects

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION
ENVIRONMENTAL IMPACTS
HYDRAULIC CONDUCTIVITY
IRRIGATION
RECYCLING
SOILS
WASTE MANAGEMENT
WASTE WATER