Source Separation of Urine as an Alternative Solution to Nutrient Management in Biological Nutrient Removal Treatment Plants

Abstract

Municipal wastewater contains a mixture of brown (feces and toilet paper), yellow (urine), and gray (kitchen, bathroom and wash) waters. Urine contributes approximately 70-80% of the nitrogen (N), 50-70% of the phosphorus (P) load and 60-70% of the pharmaceutical residues in normal domestic sewage. This study evaluated the impact of different levels of source separation of urine on an existing biological nutrient removal (BNR) process. A process model of an existing biological nutrient removal (BNR) plant was used. Increasing the amount of urine diverted from the water reclamation facilities, has little impact on effluent ammonia (NH₃-N) concentration, but effluent nitrate (NO₃-N) concentration decreases. If nitrification is necessary then no reduction in the sludge age can be realized. However, a point is reached where the remaining influent nitrogen load matches the nitrogen requirements for biomass growth, and no residual nitrogen needs to be nitrified. That allows a significant reduction in sludge age, implying reduced process volume requirements. In situations where nitrification is required, lower effluent nitrate (NO₃-N) concentrations were realized due to both the lower influent nitrogen content in the wastewater and a more favorable nitrogen-to-carbon ratio for denitrification. The external carbon requirement for denitrification decreases as the urine separation efficiency increases due to the lower influent nitrogen content in the wastewater and a more favorable nitrogen-to-carbon ratio for denitrification. The effluent phosphorus concentration decreases when the amount of urine sent to water reclamation facilities is decreased due to lower influent phosphorus concentrations. In the case of chemical phosphate removal, urine separation reduces the amount of chemicals required.

Enhanced Biogas Production From Anaerobic Co-digestion of Lignocellulosic Biomass and Poultry Feces Using Source Separated Human Urine as Buffering Agent

“…For example, the human urine is a body fluid and waste expected to be disposed of without any major application. In terms of composition in the domestic sewage, urine supplies approximately 70-80% of the nitrogen, 50-70% of the phosphorus, and 60-70% of the pharmaceutical loadings (Jimenez et al, 2015). In recent years, however, there is increased understanding that the composition of source separated urine suggests it can serve as nutrient and growth inducer for plant and microorganisms (Larsen et al, 2004;Akpan-Idiok et al, 2012;Andreev et al, 2017).…”

Struvite Recovery From Source-Separated Urine Utilizing Fluidized Bed Technology

“…The decrease of nitrogen and phosphorus loading has the potential to lower cost associated with treatment, including energy and chemical costs. Reducing the influent urine to municipal WWTP by 70% and 90% can eliminate the need for biological phosphorus and nitrogen removal (BPNR), respectively (Jimenez et al 2015). In addition to those benefits previously stated, WWTP could also experience lower required solids retention time (SRT) with most of the influent nitrogen and phosphorus eliminated due to heterotrophic growth.…”

“…Establishing a stakeholder attitude for the project with users has a strong influence on the attitude of users increases support . Installation of toilets is difficult in older buildings and is recommended for new construction rather than retrofitting due to associated costs (Jimenez et al 2015). After installation separated urine requires treatment and is often is just sent to WWTP causing intensification of influent stream due to the lack of urine diversion treatment options available in the U.S.…”

“…Urine contributes 80% of nitrogen, 50% of phosphorus, and half of contaminants of emerging concern (CECs) to municipal wastewater treatment plants (WWTP), but only contributes about 1% of flow by volume (Larsen et al 2013). Reducing the influent urine to municipal WWTP by 70% and 90% can eliminate the need biological phosphorus and nitrogen removal (BPNR), respectively and even small decreases can benefit WWTP (Jimenez et al 2015) Urine in the bladder is sterile in healthy individuals, but may be exposed to normal bacterial flora before fully exiting the body through the distal urethra. Storage of urine to inactivate pathogens before use as an agricultural fertilizer has been investigated to determine risks associated with transportation, handling, and application.…”

“…These systems allow for economical removal of solids, COD, nitrogen and phosphorus from wastewater before discharge into receiving streams when compared to the cost of chemical addition. Removal of urine from wastewater discharged from municipal communities could decrease nutrient loads in existing WWTP, therefore, increasing treatment capabilities and reducing costs (Jimenez et al 2015).…”