Biological reconditioning of sodium enriched zeolite by halophytes: case study of dairy farm effluent treatment

Abstract

Constructed wetlands (CW) containing clinoptilolite zeolite and planted with five halophytes (Sesvium portulacastrum, Juncus effusus, Suaeda monoica, Inula crithmoides and Sarcocornia fruticosa) were irrigated with treated dairy farm effluent. The CW were operated for two years with retention time ranging from 2 to 7 d. Plant species did not affect SAR which was reduced in all treatments from 4.85 to 2.59 (mmol/L)^0.5 due to ion exchange in zeolite. Halophytes increased evapotranspiration to 30 mm d⁻¹ which countered sodium removal. Zeolite planted with Sesuvium portulacastrum had 15% lower sodium percentage (ESP, F_1,118 = 12.53, p = 0.0006) and 5% higher calcium percentage (F₁,₁₁₈ = 7.44, p = 0.007) compared to non-planted zeolite, indicating reconditioning of zeolite with respect to sodium. Enhancement of SAR removal capability by reconditioned zeolite was demonstrated in 24 h batch experiments on excavated zeolite (n = 6) with saline water (SAR = 0, 17.6, 62.8, and 122.8 (mmol/L)^0.5). Zeolite from Sesuvium planted CW reduced SAR to a greater extent than non-planted zeolite and was significant for inlet SAR 17.6 which was reduced to 3.33 ± 0.3 (mmol/L)^0.5 compared to 3.68 ± 0.12 by non-planted zeolite (p < 0.05). In-situ biological reconditioning of active matrix in CW by tailored macrophytes is a novel strategy that may be applicable to other pollutants.

Graphical Abstract

Keywords:

• Halophyte
• reconditioning
• zeolites

Acknowledgments

The pilot system was kindly hosted in the Dairy Farm of Kibbutz Kfar Blum. The authors thank Israel Parks Authority for providing halophytes from the Enot Tsukim salt marsh reserve, Kibbutz Ein Gedi for cuttings of Sesuvium portulacastrum and Salt of the Earth Ltd for providing access to the Atlit salt evaporation pools. EO is grateful for the support of BRIGAID, ICA-Israel, MIGAL Galilee Research Institute and his wonderful family. AA thanks Dor Cohen for her support.

Additional information

Funding

This project received funding from the European Union’s Horizon 2020 research and innovation programme under [grant agreement No 700699].