Heavy metal contamination is a global environmental issue as it poses a significant threat to public health, and exposure to metals above a certain threshold level can cause deleterious effects in all living organisms including microbes.

This study employed Bacillus spp. with α-amylase production isolated from Malaysian hot spring for domestic kitchen food waste treatment contained grains, vegetables, chicken and tuna that mimic the food waste discharge from domestic kitchens in Malaysian household. Results showed that Bacillus licheniformis HULUB1 and Bacillus subtilis SUNGB2 possess excellent amylolytic properties. Highest α-amylase activity was obtained when both isolates were cultivated at pH 6.0 and 65 C with concentrations of 18.15 U/mL for HULUB1 and 22.14 U/mL for SUNGB2. Stability of α-amylase with significant levels of enzyme activity were recorded at 55-85 C and pH 5.0-9.0. The extracted mixed α-amylase of HULUB1 and SUNGB2 showed greatest reduction were achieved at day 12 with 45% AE 0.03 solid content at 65 C. While the mixed culture of HULUB1 and SUNGB2 displayed an enhanced effect on the food waste contents reduction with 43% AE 0.02 solid content at 45 C after day 12. The findings showed that the combination of the two Bacillus spp. isolates possessed degradation of food wastes at faster rate than α-amylase. It was also pointed out that the standard food waste (SFW) and the treatment process assimilated for this study was suitable for the growth of Bacillus spp.

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The use of biopolymers is a sophisticated method of soil and wastewater treatment as a substitute for using chemicals, which is a public health concern. A number of mechanisms, such as polymer bridging, polymer adsorption, charge neutralization (including electrostatic patch effects), coagulation/flocculation, and adsorption have been suggested to describe the destabilization of colloids and suspensions by