Performance testing of cadmium treatment in soil using broiler litter by pyrolysis for soybean planting

Abstract

Cadmium has been identified as a major toxic heavy metal contaminating in our food supply chain. This study want to purpose socio-economic and appropriate technology for ameliorate cadmium contamination in soil by propose broiler litter biochar derived from incinerate pelleted broiler litter in 2 reactor that 1st in lab-scale pyrolysis reactor (PBLBL) and 2nd in 200 liter oil drum (PBLBO) at highest temperature of 500ºC. Biochar was subsequently mixed into soil with 4 mixing rate 5.00, 10.0, 15.0 and 20.0 t ha-1. Each mixing rate was added with 5 level of Cd concentrations consisting of 0, 20.0, 40.0, 60.0 and 80.0 mg Cd kg-1soil. Those Cdcontaminated soils were used to cultivate the soybean, Chiang Mai 60 variety, and evaluation of plant growth and productions was performed. PBLBL and PBLBO incinerations with all mixing rate significantly promoted the soybean productivity higher than control. Typically, the harvest soybean seeds (cultivated in 80.0 mg Cd kg-1soil) comparing with as-received soybeans, gained the dry weight of 0, 0, 0, and 142 %, respectively, for PBLBO mixing rates of 5.00, 10.0, 15.0 and 20.0 t ha-1, while PBLBL showed of 98.0, 120, 138, and 126 %, respectively. Moreover PBLBL and PBLBO increased an availability of nutrients (e.g. N, P, K, Ca, Mg) and improved soil properties including % moisture content, pH, OM, C/N, CEC and capablyreduced Cd concentrations in soils. Satisfactory results of residual Cd in biocharmixed soil were obtained by PBLBO with mixing rate 20.0 t ha-1 and PBLBL with same mixing rate, residual Cd was about 35.0 and 31.4 mg Cd kg-1 soil. Even though the pretreat Cd-contaminated soils was high to 80.0 mg Cd kg-1 soil, the residual Cd after treatment with biochar was particularly lower than the soil quality standard allowance for habitat and agriculture for cadmium not exceeding 37.0 mg kg-1soil. Furthermore biochar from both reactor reduced Cd in soybean seed which PBLBO helped to reduce Cd in soybean seed to 0.182 mg Cd kg-1 soybean at Cd contamination of 20.0 mg kg-1soil, while PBLBL presented better results than PBLBO. This system reduced Cd in soybean seed to 0.187 mg Cd kg-1 soybean seed at Cd contamination of 60.0 mg Cd kg-1soil. This met the CCFAC standard that permits Cd in soybean seed not exceeding 0.200 mg Cd kg-1 soybean seed. Results clearly showed that both biochars incinerate in different kilns was similarly in efficiency improving the soil properties and reduce bioavailabity and phytotoxicity of cadmium-contaminated soil.