Environmental, geotechnical, and hydraulic behaviour of a cellulose-rich by-product used as alternative cover material

Deinking by-product (DBP), a cellulose-rich by-product produced in the early stages of the paper recycling process, has been used as alternative material for the construction of cover systems for municipal waste disposal facilities and acid-producing mine residues. Because of the high organic content of this material, covers constructed with it are susceptible to biodegradation and, thus, to changes in their properties with time. With the goal of identifying the biodegradation parameters that could influence the long-term behaviour of DBP covers, an experimental laboratory program was developed and a series of 15 samples of DBP were monitored in biodegradation tests for 400 d. Periods of intermittent water percolation allowed for collection of leachate. The evolution of gas and leachate production was monitored in terms of quality and quantity. According to the results obtained, the hydraulic and geomechanical properties of importance for a cover do not seem to be adversely affected by the level of biodegradation of the DBP or by mass loss. Key words: cover systems, deinking by-products, biodegradation, mass loss by gas production, mass loss by leaching.