Study of food waste degradation in a simulated septic tank

Hongjian Lin, Yuchuan Wang, Leif van Lierop, Carlos Zamalloa, Casey Furlong, Michael Keleman, Bo Hu

Research output: Contribution to journalArticlepeer-review

3 Scopus citations

Abstract

Septic systems are typically designed to treat domestic wastewater from households without access to centralized facilities. The installation of a food waste disposer (FWD) may increase the discharge of food waste (FW) into the wastewater; therefore, the installation of a FWD is discouraged in households that have a septic system. This study was conducted to determine how a typical dose of FW from a FWD can affect the performance of a septic system in terms of sewage treatment and solids accumulation. A 20-L control tank was compared with an experiment tank to which FW was added, increasing the amount of total suspended solids (TSS) by 31.3% and total chemical oxygen demands by 46.3% for a period of 110 days. Although the influent water quality changed dramatically, the effluent from the experiment tank had a substantially lower percentage increase in water quality parameters compared with the effluent from the control. It was found that in the experiment tank, 75.8% of FW TSS was degraded, whereas only 36.7% of sewage TSS was degraded, and that 18.8% of FW TSS and 44.9% of sewage TSS accumulated in the experiment tank. The addition of FW increased the scum accumulation, even though the dry matter of the scum layer was much less in quantity than the sludge layer. It also increased the lipid content in the sludge. The increase in the scum layer was mainly due to the increase in protein from the addition of the FW. Overall, compared with sewage TSS, FW TSS tends to be more biodegradable, which indicates that the impact on pumping frequency from adding FW will be insignificant.

Original languageEnglish (US)
Pages (from-to)1199-1206
Number of pages8
JournalWaste Management and Research
Volume37
Issue number12
DOIs
StatePublished - Dec 1 2019

Bibliographical note

Funding Information:
https://orcid.org/0000-0002-1368-5120 Lin Hongjian 1 2 Wang Yuchuan 1 van Lierop Leif 1 Zamalloa Carlos 1 Furlong Casey 3 Keleman Michael 3 https://orcid.org/0000-0001-9786-3336 Hu Bo 1 1 Department of Bioproducts and Biosystems Engineering, University of Minnesota, USA 2 College of Biosystems Engineering and Food Science, Zhejiang University, China 3 Emerson, USA Bo Hu, Department of Bioproducts and Biosystems Engineering, University of Minnesota, 1390 Eckles Avenue, BAE Building, St. Paul, MN 55108-6005, USA. Email: bhu@umn.edu 10 2019 0734242X19879221 4 6 2019 6 9 2019 © The Author(s) 2019 2019 International Solid Waste Association Septic systems are typically designed to treat domestic wastewater from households without access to centralized facilities. The installation of a food waste disposer (FWD) may increase the discharge of food waste (FW) into the wastewater; therefore, the installation of a FWD is discouraged in households that have a septic system. This study was conducted to determine how a typical dose of FW from a FWD can affect the performance of a septic system in terms of sewage treatment and solids accumulation. A 20-L control tank was compared with an experiment tank to which FW was added, increasing the amount of total suspended solids (TSS) by 31.3% and total chemical oxygen demands by 46.3% for a period of 110 days. Although the influent water quality changed dramatically, the effluent from the experiment tank had a substantially lower percentage increase in water quality parameters compared with the effluent from the control. It was found that in the experiment tank, 75.8% of FW TSS was degraded, whereas only 36.7% of sewage TSS was degraded, and that 18.8% of FW TSS and 44.9% of sewage TSS accumulated in the experiment tank. The addition of FW increased the scum accumulation, even though the dry matter of the scum layer was much less in quantity than the sludge layer. It also increased the lipid content in the sludge. The increase in the scum layer was mainly due to the increase in protein from the addition of the FW. Overall, compared with sewage TSS, FW TSS tends to be more biodegradable, which indicates that the impact on pumping frequency from adding FW will be insignificant. Food waste septic tank household wastewater food waste disposer sludge degradation Emerson Commercial & Residential Solutions edited-state corrected-proof Declaration of conflicting interests The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article. Funding The authors disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This study was funded by Emerson Commercial & Residential Solutions. ORCID iDs Hongjian Lin https://orcid.org/0000-0002-1368-5120 Bo Hu https://orcid.org/0000-0001-9786-3336

Publisher Copyright:
© The Author(s) 2019.

Keywords

  • Food waste
  • degradation
  • food waste disposer
  • household wastewater
  • septic tank
  • sludge

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