Comparative Evaluation of Unmodified Eggshell, Cow Bone, and Wood Shavings Biomass for the Remediation of Chromium Contaminated Soils

Heavy metal contamination of soils poses significant environmental and public health concerns, particularly in areas affected by industrial and urban activities. This study evaluated the remediation potential of eggshell (ES), cow bone (CB), and wood shavings (WS) for chromium (Cr)-contaminated soils collected from Lagos bus stop, Community Secondary School, Nkpolu, and Eagle Island in Rivers State, Nigeria. Soil samples were artificially contaminated with Cr and amended individually with ES, CB, and WS at application rates of 10, 20, and 40 g per 500 g of soil, as well as with combined biomass treatments. The amended soils were monitored for four weeks, with measurements taken at Weeks 1, 2, and 4. All biomass treatments produced progressive reductions in Cr concentrations over the experimental period, although their effectiveness varied with biomass type, application rate, soil location, and metal. The highest reduction was 99.9% with 20 g cow bone in Lagos bus stop soil, followed by 99.5% with 40 g cow bone in Eagle Island soil and 99.4% with 20 g eggshell in Nkpolu. Cow bone generally showed strong performance, particularly in Lagos bus stop and Eagle Island soils; however, eggshell and wood shavings also produced substantial reductions under specific treatment conditions. The combined biomass treatment was effective in several cases but did not consistently outperform the individual biomass materials. Overall, the findings demonstrate that eggshell, cow bone, and wood shavings have potential as low-cost biomass amendments for remediating Cr contaminated soils. Their effectiveness is associated with complementary mechanisms involving adsorption, ion exchange, complexation, and mineral precipitation. The study highlights the potential for converting locally available agricultural and animal wastes into useful materials for sustainable heavy metal remediation.