超声波提高微生物固化砂土效果的试验研究

Experimental study on improving effect of microorganism solidifying sand by ultrasonic

为了研究超声波对巴氏生孢八叠球菌及其诱导碳酸钙沉积能力的影响,利用超声(20 kHz)开展超声辐照时间(0~30 min)和超声功率强度(0~0.8 W/cm3)的正交试验,用超声处理后的菌液进行水溶液试验和砂柱加固试验.测定菌液脲酶活性、OD600、细菌颗粒分布参数、碳酸钙的产量和加固后砂柱无侧限抗压强度.分析超声辐照时间、超声功率强度、超声能量强度对碳酸钙产量的影响.结果表明,超声辐照能够引发细菌产生生理强化反应,提高菌液脲酶活性.当超声能量强度约为8 W·min/cm3时,超声辐照能够有效地提高菌液诱导生成碳酸钙的能力.经优化的辐照策略(超声功率强度为0.4 W/cm3,处理时间为20 min)进行超声辐照处理后,水溶液中和砂柱中的碳酸钙产量分别提高了28.5%和35.6%,加固后砂样无侧限抗压强度为1.25 MPa,较对照组提高了91.6%.

Orthogonal experiments of ultrasonic irradiation time(0-30 min) and ultrasonic power intensity(0-0.8 W/cm3) were conducted using ultrasound(20 kHz) in order to analyze ultrasonic effect on Sporosarcina pasteurii and its ability to induce calcium carbonate. Aqueous solution tests and sand column tests based on microbially induced carbonate precipitation were conducted using ultrasound-treated bacteria solution. Urease activity, OD600,distribution parameters of bacterial cells, amount of microbially induced CaCO3 and unconfined compressive strength of treated sand columns were measured. Effects of ultrasonic irradiation time, ultrasonic power intensity and ultrasonic energy intensity on CaCO3 amount were analyzed. Results show that ultrasonic irradiation can trigger physiological enhancement reaction of bacteria and improve the urease activity of bacterial liquid. Ultrasonic irradiation can effectively improve the ability of bacteria to induce CaCO3 with ultrasonic energy intensity of about 8 W·min/cm3. After bacterial solution was irradiated by ultrasound with the optimal irradiation strategy(ultrasonic power intensity of 0.4 W/cm3, treatment time of 20 minutes), CaCO3 amount in aqueous solution tests and sand column tests can be increased by 28.5% and 35.6% respectively. Unconfined compressive strength of MICP-treated sand sample was 1.25 MPa, which was increased by 91.6% than control samples.