acetate1 day um atm atm ppm ppb mm ______________________________________1 0 673 0 232 0 293 72 1220 2 02 0 716 0 242 0 321 72 1465 4 63 0 754 0 249 0 339 76 2060 7 0______________________________________ increased loading resulted in a build up of volatile acids and greater headspace concentrations of co this supports the hypothesis that acetate and co concentrations are related in digester type systems the direct and rapid nature of the relationship between co and acetate concentration is the subject of example 2 this example is best explained with reference to fig3 in fig3 squares connected by the solid line represent the measured concentrations of co of control samples duplicate while the triangles connected by the dotted line represent a sample to which a pulse of acetate lo mm was added at 8 5 hours all samples were prepared as in example 1 except in this case a 20 day hrt inoculum was used and handled in exactly the same fashion up until the addition of the acetate pulse subsequent to the addition of acetate indicated by the arrow on the abcissa of the graph which increased the acetate concentration the gaseous co concentration rose sharply to a level well above that measured in control samples this demonstrates the direct correlation between acetate concentration and co and further shows the relatively rapid nature of the response the correlation of co measured on a daily basis to the acetate concentrations measured on a digester system experiencing operational problems due to an organic overload is the subject of this example this experiment was conducted using was as the feedstock for a 5 liter anaerobic digester maintained at 35 u00b0 c and operated in a daily draw and fill mode the.