A pilot-scale study of electrocoagulation on phosphorus removal from animal manure and the economic analysis

Manure management is a challenge as the animal barns are tend to be larger operations. Electrocoagulation has a great potential to be applied in animal barns because it can effectively separate liquid and solid as well as nitrogen and phosphorus from animal manure. This work evaluated a pilot scale electrocoagulation with low carbon steel as electrodes working on dairy manure, shallow-pit and deep-pit swine manure. Over 66% of the phosphorus in electrocoagulation treated swine manure was recovered in sludge with less than 10% of the phosphorus in the untreated volume. The TN/P₂O₅ ratio in swine manure sludge after electrocoagulation decreased to 0.52–0.78 while it increased to 10.61–38.56 in the supernatant after electrocoagulation, which significantly reduced the risk of phosphorus overdose as manure fertiliser to pollute the environment. However, the pilot electrocoagulation removed 79.3% of the dairy manure phosphorus into sludge while the sludge volume was 48% of the total volume. The economic analysis showed that an electrocoagulation system in a barn with 2400 head grown-finish pigs for 20 years would add $1.04 and $3.32 per pig of additional annualised cost in a shallow-pit swine barn and deep-pit swine barn, respectively. The environmental benefits of manure nutrient balancing and phosphorus sustainability make it worth to develop electrocoagulation technology on animal barns.