Wang, LK and Wang, MHS (2022). Cocoa processing waste pretreatment and mobile flotation plants; In: “Evolutionary Progress in Science, Technology, Engineering, Arts and Mathematics (STEAM)”, Wang, LK and Tsao, HP (eds.), 4 (7F), STEAM-VOL4-NUM7F-JULY2022. ISBN 978-0-9890870-3-2. 43 pages. July 2022, Lenox Institute Press, MA, USA. ………..ABSTRACT: A dissolved air flotation (DAF) unit was installed at a cocoa manufacturing plant in New Jersey, USA for pretreatment of their cocoa processing wastewater. This publication introduces : (a) the DAF process system and literature review; (b) the cocoa and chocolate manufacturing procedures; (c) the DAF performance data and (d) new mobile flotation plants. The pretreatment objective is reduction of TSS to less than 300 mg/L, FOG to less than 100 mg/L, and BOD5 by over 85%. The pretreated water is discharged to a municipal wastewater treatment plant. When the DAF was operated under the 66.67% recycle mode, using 11 mg/L alum (as aluminum oxide) and 9.75 mg/L polymer, the following were the average performance : (a) influent TSS = 144 mg/L, effluent TSS = 56 mg/L (62% TSS reduction); (b) influent FOG = 115 mg/L, effluent FOG = 47 mg/L (59% FOG reduction). Although the influent TSS ranged from 78 mg/L to 1460 mg/L during the operational period, the DAF effluent TSS were always less than 60 mg/L. DAF influent FOG was as high as 3108 mg/L, but DAF effluent FOG was controlled at below 100 mg/L at all times. The target 85% BOD5 reduction was achieved. Average concentrations of floated sludge was over six percent. Mobil plants of DAF, dissolved air flotation-filtration (DAFF), DAF-DAF, DAF-DAFF, etc. are also developed for emergency, seasonal, or temporary services to small customers.