title: Use of microbial activity parameters for determination of a biosolid stability index.
abstract: Variations in microbial activity during the aerobic digestion of sludge generated at wastewater treatment plants were studied. Results obtained by the measurement of enzymatic activity and microbiological parameters were compared with those determined by traditional methods (COD, suspended solids, etc.). Their variation with digestion time was monitored for batch digestion over a period of 135 days. The relationship between these measurements and control parameters of the sludge was also investigated. It was found that the traditional physicochemical and microbiological parameters present a series of problems which detract from their usefulness. The enzymatic parameters dehydrogenase activity (primary metabolism) and esterase activity (secondary metabolism) are better able to characterise the process, and the ratio of these two variables may be used to estimate the degree of endogenesis and, consequently, the degree of stability of the aerobic sludge digestion. In addition, these techniques are swift and simple to employ.
authors.affiliation: Department of Chemical Engineering, Food Technology and Environmental Technology, University of Cadiz, CASEM, Campus Río San Pedro s/n, 11510 Puerto Real, Cádiz, Spain.
authors.forename: J Barragán
authors.initials: JB
authors.lastname: Sánchez
authors.forename: J M
authors.initials: JM
authors.lastname: Quiroga Alonso
authors.forename: M D
authors.initials: MD
authors.lastname: Coello Oviedo
mesh_terms: D004755:Enterobacteriaceae / Q000201:enzymology*; D004950:Esterases / Q000378:metabolism; D006862:Hydrogen Sulfide / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D010088:Oxidoreductases / Q000378:metabolism; D010100:Oxygen / Q000378:metabolism; D012722:Sewage / Q000382:microbiology*; D013997:Time Factors; D014865:Waste Disposal, Fluid / Q000295:instrumentation / Q000379:methods*; D018508:Water Purification / Q000295:instrumentation / Q000379:methods*
chemical_list: D012722:Sewage; D010088:Oxidoreductases; D004950:Esterases; D010100:Oxygen; D006862:Hydrogen Sulfide