Phosphorus recovery from swine wastewater by struvite precipitation: compositions and heavy metals in the precipitates

Abstract

A B S T R A C TRecovering phosphate and ammonium as struvite from swine wastewater has gained importance as a means of relieving water eutrophication and the scarcity of phosphorous rock resources. Recently, it has been generally accepted that the quality of recovered products can facilitate the market development of nutrient recovery. In this work, the compositions and heavy metals in the recovered products of struvite recovered from swine wastewater were investigated by dosing industrial-grade (IG) MgO and Mg(OH) 2 as the low-cost magnesium sources. Results revealed that struvite (34.4-40.4% weight ratio) was the dominant mineral in the precipitates, mixing up with amorphous calcium phosphate (7.8-9.5%) and residual IG-MgO or IG-Mg(OH) 2 (9.0-19.3%). The inactive components of organic matter and refractory materials occupied significant parts of the precipitates, with their levels of 14.1-20.6% and 18.9-24.4%, respectively. It was noticeable that Cu and Zn in the collected solids were above the legal limits, suggesting that pretreatment methods were necessary to remove heavy metals from swine wastewater before struvite recovery.

Fractionating various nutrient ions for resource recovery from swine wastewater using simultaneous anionic and cationic selective-electrodialysis

“…Chemical compositions and their concentration levels of the simulated swine wastewater (feed stream) were referred according to the description of Shen et al (2016) and . The feed stream and the initial compositions of other streams were presented in The electrodialysis configuration consisted of five closed loops, including the anionic product, cationic product, brine, feed and electrode rinsing streams.…”

“…Besides, dosing divalent cation (Mg 2+ or Ca 2+ ) chemicals to trigger M A N U S C R I P T A C C E P T E D ACCEPTED MANUSCRIPT 5 phosphate precipitation is another limiting factor for phosphorus recovery, since it contributes a major part of the total costs (Hövelmann et al, 2016). Several cheap cation agents, such as CaO, MgO, Mg(OH) 2 , brucite and brine were investigated as the cost-effective sources (Li et al, 2018;Shen et al, 2016;Hövelmann et al, 2016;Liu et al, 2013). From another point of view, the digestive waste stream contains abundant Ca 2+ and Mg 2+ with the concentration range of 40-200 mg/L (Ye et al, 2011;Herrmann et al, 2016), which can be used as the potential sources for phosphate precipitation.…”

Optimization of the fluidized bed for crystallization process: seed fluidization study

“…In recent years, studies have been conducted to determine crystallization conditions. The factors reaction pH, reaction molar ratio, and supersaturation are considered to be the main factors influencing the crystallization process [12][13][14][15][16].…”

Combining magnesium ammonium phosphate precipitation with membrane processes for ammonia removal from methanogenic leachates

“…Shen et al . () investigated MAP precipitation from swine wastewater laying emphasis on the product composition. The precipitate was found to contain up to 20.6% organic matter and up to 24.4% refractory materials.…”

“…Several recent research works have focussed on the purity of the precipitate obtained and shed light on the organic impurities in the product. Shen et al (2015) investigated MAP precipitation from swine wastewater laying emphasis on the product composition. The precipitate was found to contain up to 20.6% organic matter and up to 24.4% refractory materials.…”