Biological nutrient removal enhancement using fermented primary and rotating belt filter biosolids

Gholamreza Bahreini; Moustafa Elbahrawi; Elsayed Elbeshbishy; Domenico Santoro; George Nakhla

doi:10.1016/j.scitotenv.2021.148947

Biological nutrient removal enhancement using fermented primary and rotating belt filter biosolids

Sci Total Environ. 2021 Nov 20:796:148947. doi: 10.1016/j.scitotenv.2021.148947. Epub 2021 Jul 10.

Authors

Gholamreza Bahreini¹, Moustafa Elbahrawi², Elsayed Elbeshbishy³, Domenico Santoro⁴, George Nakhla⁵

Affiliations

¹ Department of Civil and Environmental Engineering, Western University, London, ON N6A 5B9, Canada. Electronic address: gbahrein@uwo.ca.
² Department of Civil and Environmental Engineering, Western University, London, ON N6A 5B9, Canada.
³ Civil Engineering Department, Ryerson University, Toronto, ON M5B 2K3, Canada.
⁴ USP Technologies, Atlanta, GA 30309, USA.
⁵ Department of Civil and Environmental Engineering, Western University, London, ON N6A 5B9, Canada; Department of Chemical and Biochemical Engineering, Western University, London, ON N6A 5B9, Canada.

PMID: 34273832
DOI: 10.1016/j.scitotenv.2021.148947

Abstract

This research compared the impact of two primary treatment options (i.e. primary clarification and rotating belt filtration (RBF)) on biological nutrients removal (BNR) process, using sludge fermentation liquid (SFL) as a carbon source. The liquid fraction of both fermented primary and RBF sludges comparably enhanced BNR. Despite the significant contribution of the unpurified SFL to the sharp increase in nutrient levels; i.e. 47%-64% (primary effluent; PE), and 45%-53% (RBF) of the soluble nitrogen and phosphorus loads; readily biodegradable COD and volatile fatty acids (VFAs) fractions of the combined feed increased significantly (2.5-6.1 times), compared to the original feed by additional SFL. Removal efficiencies in the reactors reached 57% (total nitrogen) and 92% (total phosphorus) after addition of SFL. Effluent nitrogen and phosphorus of the two reactors were close in the range of 15 ± 6 mg N/L, and 0.5 ± 0.3 mg P/L, respectively. Kinetics studies showed denitrification rates of 1.3, and 1.13 kg NO₃-N/m³.d for primary effluent and RBF effluent-fed reactors, respectively. Phosphorus release rates were 11.7 and 9.7 mg PO₄-P/g VSS.h, for primary, and RBF effluents, respectively; showing 20%-22% lower rates in the RBF SFL. Incorporating experimental data into a plant-wide model for a 100 MLD facility receiving typical medium strength wastewater, showed that although primary treatment enhanced the biogas production by 96% (primary clarification) and 62% (RBF) trains; combined fermentation and anaerobic digestion was effective to enhance the biogas production by 59% on average, compared to the base scenario without primary treatment. Additionally, if primary clarification exists, then the addition of fermentation results in additional revenue of C$1890/d in the plant, considering additional revenue of C$2230/d due to VFA generation in contrast to only C$340/d loss due to the reduced methane production.

Keywords: BNR; Dark fermentation; Internal carbon; Primary sludge; RBF sludge.

MeSH terms

Bioreactors*
Biosolids
Nutrients
Phosphorus
Sewage*

Substances

Biosolids
Sewage
Phosphorus