Treated Seawater as a Magnesium Source for Phosphorous Recovery from Wastewater—A Feasibility and Cost Analysis

Abstract

Conventional resources of phosphorous are at high risk of depletion in the near future due to current practices of its exploitation, thus new and improved exploration methodologies need to be developed to ensure phosphorous security. Today, some treatment plants recover phosphorous from municipal wastewater as struvite (MgNH4PO4·6H2O). Magnesium is often added to the wastewater as MgCl2·6H2O to facilitate the phosphorous recovery. However, the use of magnesium increases the costs of the process and is not aligned with sustainable development, therefore, alternative magnesium sources have to be found. The current study analyzes the feasibility of integrated membrane processes for magnesium recovery from seawater for utilization in the phosphorous recovery process. The integrated membrane systems consist of nanofiltration (NF), membrane distillation (MD), and membrane crystallization (MCr). The lowest associated cost is found for standalone NF treatment. However, the additional treatment with MD and MCr produces fresh water and salts like NaCl or potentially other valuable minerals at the expense of low-grade heat.

Nutrient recovery from manure digestate by using waste magnesite powder and bone meal as sustainable substitutes for struvite precipitation

“…Therefore, the final product quality must be analyzed, especially when unconventional additives are used for struvite precipitation. Seawater 23,24 and bittern 25 are some substitutes that have been previously used as Mg 2+ sources and nutrient recovery efficiencies were comparable to efficiencies attained with pure chemicals. Another option is to use waste magnesite powder (WMP), which is a byproduct of the manufacturing process of converting magnesite (MgCO 3 ) into MgO 26 .…”

Current available treatment technologies for saline wastewater and land‐based treatment as an emerging environment‐friendly technology: A review

“…Similarly, precipitate of salts with calcium carbonate can be facilitated by reactive adsorption of CO 2 on sodium hydroxide in an integrated membrane‐based process (Drioli et al, 2004; Quist‐Jensen et al, 2016). Likewise, crystallization and recovery of magnesium ions up to 98% to 100% from the hypersaline wastewater was achieved in a small lab scale study by using sodium hydroxide (Cipollina et al, 2015).…”