Process |
Advantages |
Disadvantages |
Coagulation/flocculation |
Inexpensive capital cost, Good sludge settling and dewatering characteristics, Significant reduction in the chemical oxygen demand and Bacterial inactivation capability. |
Requires adjunction of non-reusable chemicals (coagulants, flocculants, aid chemicals). Physicochemical monitoring of the effluent (pH). Increased sludge volume generation (management, treatment, cost), Low removal of arsenic [61]. |
Membrane filtration |
Small space requirement, simple, rapid, and efficient, even at high concentrations. No chemicals required. Low solid waste generation. Eliminates all types of dyes, salts, and mineral derivatives. |
Investment costs are often too high for small and medium industries. High energy requirements. The design of membrane filtration systems can differ significantly [62]. |
Biological methods |
Biodegradation of organic contaminants is simple, economically attractive, and well accepted by the public. White-rot fungi produce a wide variety of extracellular enzymes with high biodegradability capacity. High removal of biochemical oxygen demand and suspended solids. |
Requires management and maintenance of the microorganisms and/or physicochemical pre-treatment. Slow process (problems of kinetics). Low biodegradability of certain molecules (dyes). Poor decolorization, possible sludge bulking and foaming [63]. |
Ion exchange |
Wide range of commercial products available from several manufacturers. Technologically simple (simple equipment). Well-established and tested procedures; easy control and maintenance. |
Large volume requires large columns. Rapid saturation and clogging of the reactors. Saturation of the cationic exchanger before the anionic resin (precipitation of metals and blocking of the reactor) [64]. |
Photochemical |
No sludge production. |
Formation of by-products [65]. |
Chemical precipitation |
Technologically simple and integrated physicochemical process. It is economically advantageous and efficient. Very efficient for metals and fluoride elimination. Significant reduction in the chemical oxygen demand. |
Chemical consumption (lime, oxidants, H2S, etc.). Ineffective in the removal of the metal ions at low concentration, high sludge production, handling, and disposal problems (management, treatment, cost) [61]. |
Adsorption |
Technologically simple (simple equipment) and adaptable to many treatments. Target a wide variety of contaminants. Highly effective process. |
Relatively high investment, non-destructive processes, non-selective methods. Performance depends on the type of material [66]. |