Green Synthesis of Fe₃O₄@Carbon Filter Media for Simultaneous Phosphate Recovery and Nitrogen Removal from Domestic Wastewater in Biological Aerated Filters

Abstract

Domestic wastewater depth processing and reclamation are essential in the alleviation of global water shortage. In this study, an innovative filter media (i.e., Fe3O4@Carbon filter media [FCM]) was synthesized and subsequently used in a biological aerated filter (BAF) for simultaneous phosphate recovery and nitrogen removal (SPN) from domestic wastewater. The performance of FCM was compared with the commercially available ceramsite (CAC). The results showed that the performance of FCMBAF was better than that of CACBAF; as far as SPN is concerned, the magnetic field of FCMBAF could accelerate the growth rate of biofilm. Moreover, the nitrospira and nirK gene copy numbers of FCMBAF were considerably higher than those of CACBAF. Interestingly, the interconnectivity and uniformity of pores were also suitable for the microdistribution of biofilm, where different aerobic and anaerobic zones of the FCM were formed. This facilitates the microinteraction between the key microorganisms and the filter media that successfully enhanced the nitrogen removal. The phosphate recovery was attained via hydroxyapatite (Ca10(PO4)6(OH)2) formation, which resulted from the reaction between phosphate (PO4 3–) and FCM. The average effluent concentrations of total organic carbon (TOC), total nitrogen (TN), ammonia nitrogen (NH4 +-N), and PO4 3– were 8.12, 6.18, 0.997, and 0.073 mg/L of FCMBAF, respectively, which were lower than those from the national standard (CODcr ≤ 50 mg L–1, NH4 +-N ≤ 5.0 mg L–1, TN ≤ 15 mg L–1, TP ≤ 0.5 mg L–1, GB 18918–2002, first standard). Thus, FCM demonstrated a promising potential for SPN and wastewater recycling of BAF in domestic wastewater treatment.

Use of Shredded Recycled Plastic as Filter Bed Packing in a Vertical Flow Filter for Onsite Wastewater Treatment Plants: Preliminary Findings

“…The interconnectivity and uniformity of the pores were also suitable for biofilm microdistribution, where different FCM aerobic and anaerobic zones were formed. This process facilitates micro-interactions between key microorganisms and the filtration media [33].…”

An Insight to the Various Applications of Hydroxyapatite

“…Phosphate removal achieved via consumption by PAOs and HAp crystallisation on the biofilms generated in the A/OBF reactor. HAp was used by Bao et al [92] for phosphate recovery from iron(III) oxide/carbon filter media (FCM) in a biological aerated filter (BAF). Phosphate recovery was achieved by the reaction of calcium ions, phosphate ions and hydroxide ions to form and precipitate HAp on the FCM.…”

Optimize the Preparation of Novel Pyrite Tailings Based Non-sintered Ceramsite by Plackett-Burman Design Combined With Response Surface Method for Phosphorus Removal

“…Certainly, the biomass, bioactivity, and filtration action in BAFS is highly depending on the media character, and it also significantly determines the investment of construction and operating cost. Thus, research has reported focusing on the investigation of media performance of different materials in BAFS ( Qiu et al, 2010 ; Bao et al, 2016 ; Bao et al, 2019 ), and ceramic particle was found as a favorable candidate due to its large specific surface area, high mechanical strength, and biological affinity ( Yue et al, 2009 ; Han et al, 2013 ; Yang et al, 2015 ). However, the phosphorus removal by commercial ceramsites was unfavorable as yet ( Jiang et al, 2014 ), and it is significant to propose strategies to improve its phosphorus removal.…”