fall within the scope of the present invention including pneumatic static such as baffles 28 mechanical and hydraulic the purpose of the inline agitation is to maintain dispersion of the sludge and prevent premature settling other forms of mixing for maintaining dispersion also fall within the scope of the present invention for example in line mixers may be used in the pipes until the treated sludge reaches the sludge concentrator tank 17 in the sludge concentrator tank 17 a concentrated phase of the sludge separates out from clarified water by settling to the bottom of the sludge concentrator tank 17 while the clarified water rises to the top of the sludge concentrator tank 17 in the present invention the flow through the solid reagent contactor bed 14 is adjusted in such a manner that the dissolution rate of the solid reagent tablets 19 into the sludge slurry is between about 0 01 to about 0 5 based on an average volumetric flow through the bed as the solid reagent tablets 19 or pallets dissolve in the sludge their size becomes smaller and as the spacing between the solid reagent tablets 19 increases new solid reagent tablets are introduced to replace the size diminished solid reagent tablets fig3 illustrates a method to accomplish tablet replenishment the solid reagent tablets 19 may be dropped through channels 15 15 a 15 b and 15 c additional such channels may be added for each screen level another option is a tapered space between solid reagent contactor bed 14 wall 42 and screens 31 through which the solid reagent tablets 19 could be introduced through channel 15 by dropping the solid reagent tablets 19 by gravity such that they slide and arrange onto the screens 31 providing for means.