Coagulation-flocculation of feedlot wastewater using different mixing devices

SANTIAGO N. FLEITE; ANA R. GRACÍA; CHRISTIAN DE LOS SANTOS; ALICIA F. DE IORIO; CASSANELLO MIRYAN

Congreso; CAIQ2019 ? X Congreso Argentino de Ingeniería Química; 2019

Feedlots are sources of highlypolluted wastewaters in agro-productive systems, produced when largeamountsof runoff mix with pen manure, reaching water bodies or specialreservoirs. This wastewater must be disposed relatively fast to avoidpollution risks. A promising alternative of treatment for thiseffluent is a physicochemical treatment based in a continuouscoagulation-flocculation system. This work aims at optimizing thecoagulation-flocculation system for a feedlot production. Batchexperiments were carried out to define and optimize the dose ofcoagulant aids. Using the optimal batch conditions, continuouscoagulation was examined by promoting it inside a horizontal tube,either empty (ET) or provided with a contraction-expansion mixingdevise (CE) or a Koflo type static mixer (SM). Chemical oxygen demand(COD), total nitrogen (TN), total phosphorous (TP), turbidity (NTU),and the settling curves were determined. The solid flux method wasused for settling data analysis. Iron (III) chloride, calciumhydroxide and magnesium hydroxide were tested as coagulant aids. Itwas found that the best strategy was the combined addition of ironchloride and subsequently one of the hydroxides to compensate theacid characteristics of iron (III). Removal efficiencies reached asmuch as 80% of COD, 65% of TN and 90% of TP. Settling curves werealso improved, together with better limit solid flux valuesdetermined for continuous flocculation compared to batch assays. Thecombined addition of these coagulant aids constitutes acost-effective alternative for recovering phosphorous, nitrogen andorganic matter from the effluent and prevents bulking effects.p { text-indent: 0.4cm; margin-bottom: 0.25cm; direction: ltr; line-height: 115%; text-align: justify; background: transparent none repeat scroll 0% 0%; }p.western { font-family: "Times", serif; }p.cjk { }a:link { color: rgb(0, 0, 255); text-decoration: underline; }