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Stimulation of Native Microorganisms for Improving Loose Salty Sand

Kalantary, Farzin, Abbasi Govanjik, Dariush, Safdari Seh Gonbad, Mahdi
Geomicrobiology journal 2019 v.36 no.6 pp. 533-542
bacteria, calcite, compression strength, culture media, desertification, drought, dry season, dust, hydrolysis, saline soils, salinity, salt content, salt lakes, salt tolerance, sand, sandy soils, soil stabilization, urea, water harvesting, wind erosion, West Asia
Prolonged droughts and excessive water harvesting in western Asia has accelerated desertification and caused longer dry seasons of salt lakes. The Aral Sea experience has proven that dust from saline soil is a serious health issue. Various stabilization techniques to reduce wind erosion have been used in the past. However, in recent years, a potentially viable method has been developed; microbial induced calcite precipitation (MICP) has been introduced as a method of soil stabilization, though its effectiveness in saline soils remains to be examined. The effect of salt content in loose sandy soil on calcite precipitation of calcite through stimulation of native bacteria is investigated in this article. Samples with salinity up to 30% salt content were prepared and treated with different culture medium compounds. A number of tests were used to evaluate the effect of the mentioned parameters. The results show that improvement increases with increasing salinity up to 5% salt, and further increase in salinity reduces the effectiveness of improvement. It is also shown that the addition of urea in the culture medium has a significant effect on the urea hydrolysis which resulted in a five-fold increase in compressive strength. Four native strains of halotolerant urease-positive bacteria were also identified.