Abstract
This study investigated the use of iron and aluminum and their combinations as electrodes to determine the technically sound and economically feasible electrochemical approach for the treatment of anaerobic digestion effluent. The results indicated that the use of iron as anode and cathode is the most suitable solution among different electrode combinations. The reduction of turbidity, total chemical oxygen demand, total phosphorus, total coliforms, Escherichia coli, Enterococci, and phages in the reclaimed water were 99%, 91%, 100%, 1.5 log, 1.7 log, 1.0 log, and 2.0 log, respectively. The economic assessment further concluded that the average treatment cost is $3 per 1000 L for a small-scale operation handling 3000 L wastewater/day. This study demonstrated that the electrocoagulation (EC) is a promising technique for the recovery and reclamation of water from anaerobic digestion effluent. Even though its energy consumption is higher and the nitrogen removal is insufficient compared to some conventional wastewater treatment technologies, there are several advantages of the EC treatment, such as short retention time, small footprint, no mixing, and gradual addition of coagulants. These features make EC technology applicable to be used alone or combined with other technologies for a wide range of wastewater treatment applications.
Highlights
Anaerobic digestion (AD) can be perceived as a pretreatment process to reclaim the water from concentrated organic waste streams
This study investigated the effects of different electrode combinations of Fe and Al on the EC treatment of AD effluent and determined the preferred electrode configuration yielding maximum removal of solids and other contaminants (total chemical oxygen demand and total phosphorus (TP))
They consumed the same amount of energy (6.5 Wh) to treat 500 mL AD effluent
Summary
Anaerobic digestion (AD) can be perceived as a pretreatment process to reclaim the water from concentrated organic waste streams. Electrocoagulation (EC) is an emerging technology for the removal of solid particles and other contaminants from high-strength wastewater (e.g., pulp and paper wastewater, animal wastes, leachate, and industrial wastewater) [5,6,7]. It has been studied by numerous research groups to remove metals [8,9], organic matters [10,11,12], nutrients [13], and microorganisms [14,15] from a variety of wastewaters. Compared to the conventional coagulation–flocculation process, EC has several advantages, such as in situ coagulant production induced by dissolving metal using electric current, combination of three processes (coagulation, flocculation, settling) in a single step, shorter reaction/retention time, and removal of small particles and color-causing compounds [9,10,16]
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