Effect of decomposition on physical properties of fibrous peat

Abstract

Organic matter in peat deposits undergoes slow microbial decomposition, which causes permanent material change, including reduction in volume of solids, and is a significant factor in the development of creep settlements for such deposits. Microorganisms accountable for decomposition are readily available in peat, although generally less populous compared with other soils on account of the unfavourable environment. This paper presents a novel experimental laboratory study that stimulates the growth of microorganisms in a fibrous peat and hence its decomposition rate. The carbon/nitrogen ratio and pH value of the peat were adjusted within optimum ranges for microbial activity to occur by blending sufficient amounts of pulverised fuel ash and urea with the wet peat. This process did not adversely affect indigenous microbial populations within the peat. Blended material was incubated aerobically and anaerobically at 30?C over periods of up to 126 days. Microbial populations increased by approximately 3500- and 1800-fold under aerobic and anaerobic incubation, respectively, which was an indicator of increased decomposition rate. Water content, specific gravity of solids, volatile organic content and fibre content were measured both before and after incubation treatment. Fibre content was found to be approximately inversely proportional to incubation period, with relatively greater reductions in fibre content occurring for blended material under aerobic conditions.