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Peat is known as problematic ground with low bearing capacity and extensively high compressibility. Bio-cementation or commonly known as microbial-induced calcite precipitation (MICP) has been recently introduced as a ground improvement alternative for peat under waterlogged condition. Using isolated bacteria strains P19 and P21 from tropical peat, it is found that unconfined compression strength (UCS) increases with bacteria concentration at a reducing rate. A maximum unconfined compressive strength of 82.05 kPa was measured with bacteria strain P21 at 108 CFU/mL. For the range of cementation reagent varying from 0.1 to 4.0 mol/kg, the largest strength improvement occurred at 1 mol/kg and 2 mol/kg using indigenous bacteria and bacteria strain P21, respectively, for peat with sand content of 25%. At 4.0 mol/kg, the cementation reagent has detrimental effect to MICP resulting in significant reduction in strength. Due to MICP, the UCS of peat increases with sand content. Calcium carbonate precipitation results in a reduction of permeability and an increment of strength of peat–sand mixture under a submerged condition up to 28 days.

Urease were known to catalyze the conversion of urea to ammonia and carbon dioxide. Microbial urease has demonstrated its benefits in wide biotechnological, agricultural, medicinal and engineering application. There are number of diverse microbial species contribute to urease activity in different natural habitats like soil, ocean and in various geological formation. For this study, urease bacteria were screened and isolate from acidic peat in Sarawak, Malaysia. Five distinct and diverse bacterial strains that were able to produce urease constitutively were selected to be characterized with respect to morphology, biochemical test, growth conditions and urease activity. The selected strain showed their capability to precipitate calcium carbonate (CaCO3). Hence, the isolates could be potential source of acid ureases that can be use in various industrial utilizations. 16S rRNA sequencing and phylogenetic analysis found that the selected isolates belong to the genus of Bacillus.

Peat is known as problematic ground with low bearing capacity and extensively high compressibility. Ordinary Portland cement (OPC) and lime were usually used to tackle unfavourable characteristics of peat by improving it with its cementation effect. However, little was known of the effect of bio-cementation towards peat improvement. Bio-cementation or commonly known as Microbial-induced calcite precipitation (MICP) has been recently introduced as a ground improvement alternative for geotechnical engineering application. MICP performed by utilising metabolic pathways of non-pathogenic urealytic bacteria that precipitates calcium carbonate (CaCO3) crystal as cementation binder that seal soil particles together increasing soil strength. MICP of inorganic soil was extensively explored, and only limited was done for organic soil. This study explores on the effect of different surcharge preloading of 18kPa, 36kPa and 48kPa towards Microbial-Induced Calcite Precipitation (MICP) treatment of tropical peat. Fibrous peat studied were obtained from Miri, Sarawak and cured under a submerged condition with different vertical preload for seven days. Laboratory study including unconfined compression test, quantification of carbonates precipitated, and moisture content of stabilised specimens was observed to evaluate the performance of stabilisation effort. Unconfined compressive strength (UCS) of treated specimens was observed to be higher than untreated specimens with the highest increase of UCS up to 469%. However, CaCO3 precipitation amount for this study was observed to decrease with increasing surcharge preload.