Technical Bulletin No. 0028: Report on Semi-Chemical Wastes
The enclosed report represents a portion of the research conducted at Virginia Polytechnic Institute during the year 1948-49. The remainder of the completed work will be presented in another report which will be distributed shortly. Several studies which were in their early states when this report was prepared are not included. These also will be included in future reports. Fundamental studies included in this and the previous semi-chemical report are of importance in that they point to lignin compounds as the major source of color, salts of acetic acid and hemicellulose as the major cause of the oxygen demand, and wood fines as responsible for the bulk of the suspended solids present in the wastes. Direct aeration was found to have little effect on the BOD. The waste oxidizes rapidly in the presence of aerobic seed material producing relatively high BOD reductions but little color reduction. Chemical coagulation with lime is effective in removing color and a portion of the BOD, however, the sludge obtained from this treatment cannot be dewatered. The re-carbonation technique reported herein did not improve dewaterability. To date biological treatment methods appear most promising and both aerobic and high rate anaerobic experiments are being conducted on a laboratory pilot plant scale. Considerable attention has been given recovery possibilities, however, it has been concluded that such a process can only be developed on a larger scale.