Full-Scale Laboratory Study into Clogging of Pipes Permeated with Landfill Leachate

摘要

Full-scale high-density polyethylene pipes of external diameter 0.05 and 0.1 m, and internal diameter 0.04 and 0.08 m, were permeated with leachate to characterize the changes in select leachate constituents within the pipes for three different flow rates (0.25, 0.55, and 1.2 L/s). Chemical oxygen demand of 10 to 25% and calcium removal of 25 to 50% occurred within the pipes for each flow rate tested. After 5 months of operation, clog material accumulated within the pipe contained on average 40 and 45% of volatile and inorganic solids, respectively, indicating that biological and mineral solids contributed to pipe clogging. Hydromagnesite (Mg_5(CO_3)_4(OH)_24H_2O) was the mineral component of the inorganic solids. For all other conditions being generally equal, after 5 months of operation, the 0.08-m internal diameter pipes accumulated more clog mass than the 0.04-m internal diameter pipes. However, the 0.04-m diameter pipes experienced a greater reduction in cross section area for fluid flow than the 0.08-m diameter pipes. Thus, smaller diameter pipes may experience quicker reduction in hydraulic performance than larger pipes for all other conditions being equal.