Application of soil slurry respirometry to optimise and subsequently monitor ex situ bioremediation of hydrocarbon-contaminated soils

Abstract A protocol to monitor respiration as O 2 consumption in soil slurries using the Strathtox ® respirometer was developed and tested on four soils from brownfield sites. Respiration rates (mg l −1  h −1 ) of soil slurries in the Strathtox ® were compared with rates (μl min −1 ) of field moist soils analysed using the Columbus Oxymax ® ER10 respirometer. One of the soils (99612B), historically contaminated with diesel, was further studied by monitoring the effect of inorganic NH 4 NO 3 liquid nutrient on enhancing respiration rate. Soil microcosms were monitored continuously on the Oxymax ® or sampled at 24, 48 and 72 h intervals, prepared as soil slurries, and analysed on the Strathtox ® . On the full-scale remediation project (∼6000 m 3 ) soil 99612B was treated as a biopile with spent mushroom compost (SMC) amendment and respiration rates monitored in samples over an 8-week period. In the laboratory microcosm experiment and full-scale bioremediation treatment described, correlation was found for respiration rates between the two respirometry systems.