Wastewater Treatment and Resources Recovery in Paper and Pulp Industry

The Lenox Institute of Water Technology (LIWT) and Krofta Engineering Corporation (KEC) have many significant accomplishments in the field of environmental engineering. Their most important academic and engineering contributions are development of a humanitarian flotation institute, LIWT, and a series of circular flotation process equipment based on their unique “zero velocity concept.” Of all process equipment developed by LIWT-KEC, Spracell dissolved air flotation (DAF) clarifier is the best and has had 1,000+ installations around the world. The goals of LIWT-KEC are developing highly efficient and low-cost process equipment and sustainable technologies, protecting human and environmental benefits, and promoting world peace. The senior author of this publication was the United Nations Industrial Development Organization (UNIDO) Senior Advisor responsible for the introduction of Spracell DAF technology along with other US technologies to developing countries. Spracell DAF has many advantages compared to conventional equivalent technologies: (a) it has very low retention time, about 3 minutes; (b) it has a high specific clarification capacity (4–5 gpm/sqft) and very small surface area requirement; (c) its purchase cost is lower than any other system of comparable performance; (d) its installation cost is low; (e) it maintains its value because its relocation can be easily accomplished; (f) its space requirements are minimal because of its low headroom; (g) it can be erected above ground level to save land space; (h) it is easy to clean because the DAF tank is completely open, and its bottom is self-cleaning during operation; (i) its clarification efficiency is high: DAF effluent total suspended solids (TSS) is in the range 20–30 mg/L and its thickened sludge consistency is 2%–3%, thus no further sludge thickening is needed; (j) small Supracell DAF is delivered fully prefabricated; larger units are delivered in parts which flange together; and (k) no heavy foundation or support structure is needed as the total load factor when filed with water weighs less than 150 lb/sqft. Supracell DAF can be applied to the paper and pulp industry for whitewater clarification, secondary fiber recovery, titanium dioxide recovery, WWTP secondary clarification, lagoon algae separation, and sludge concentration. This chapter introduces DAF history, applications, process equipment, components, flow diagrams, operations, advantages, advances, and case histories. This publication is one of memoirs written to document the accomplishments of LIWT-KEC in memory of Dr. Milos Krofta and all deceased Lenox professors.