Treatment of post hydrothermal liquefaction wastewater and suitability for hydroponic lettuce production

Jesse, Samuel David

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https://hdl.handle.net/2142/104923 Copy

Description

Title

Treatment of post hydrothermal liquefaction wastewater and suitability for hydroponic lettuce production

Author(s)

Jesse, Samuel David

Issue Date

2019-04-25

Director of Research (if dissertation) or Advisor (if thesis)

Davidson, Paul C.

Committee Member(s)

• Zhang, Yuanhui
• Margenot, Andrew J.

Department of Study

Engineering Administration

Discipline

Agricultural & Biological Engr

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

M.S.

Degree Level

Thesis

Keyword(s)

• PHWW
• hydrothermal liquefaction
• wastewater treatment
• filtration
• metals
• pathogens
• hydroponics
• food safety
• lettuce production
• CEA

Abstract

The hydrothermal-liquefaction of biowaste into biocrude oil has the potential to address the food-energy-water (FEW) nexus in junction with food production and water filtration using the wastewater from the process. This aqueous byproduct of the HTL process, post-hydrothermal liquefaction wastewater (PHWW), has the potential to be used as a means of providing nutrients and water to crop production systems. In order to effectively used in food production, PHWW as a crop fertilizer has to be established as being productive and safe. The literature indicates that PHWW likely is free of pathogens and has nutrients vital to plant growth, but that there are also potential contaminants that may inhibit plant growth or pose a food safety risk. The evaluation of PHWW as a potential fertilizer and the methods to produce a fertilizer treatment using PHWW have not been established and little research exists on crop production using PHWW. This research aims to fill this gap by evaluating different treatments of PHWW and investigating whether lettuce can be hydroponically growth with sufficient nutrients and safe for heavy metals and E.coli/coliforms. For different treatment combinations of PHWW dilution factor, filtration type, and nitrification reaction, the results indicate that concentrations of cadmium, lead, and arsenic in the raw PHWW were well below the maximum recommended concentrations set by the Environmental Protection Agency (US EPA) for Water Reuse. In addition, the treatment methods in this study achieved percent removals ranging from 82-100% for cadmium, 99-100% for mercury, 75-99.5% for lead, and 71-99% for arsenic. The presence of E. coli/coliforms were not detected in raw PHWW or PHWW treatments. Nitrogen in the raw PHWW was predominantly in the total N form over the nitrate form, preventing it from being readily available to plants. After nitrification was induced for a week, the concentration of NO3+NO2 increased by 1.75 mg/L in the untreated 5% PHWW mixture but remained unchanged or decreased for all other treatment mixtures. Phosphorous was not present at sufficient concentrations for plant growth. From this, the hydroponic lettuce production of four different treatment mixtures of PHWW were compared to commercial hydroponic fertilizer for yields and heavy metals risk. Hydroponic fertilizer (Treatment 1) had the highest total dry yield of all five treatments; 3.06 times higher than Treatment 2 (diluted PHWW with sand filtration), 3.5 times higher than Treatment 3 (diluted PHWW with sand+carbon filtration), and 2.6 times higher than Treatment 4 (diluted and nitrified PHWW with sand filtration), and 1.3 times higher than Treatment 5 (diluted PHWW with sand filtration and supplemented hydroponic fertilizer). Findings also indicate that while PHWW was below the US Department of Agriculture Foreign Agriculture Service maximum levels for cadmium, lead, and mercury in food, the concentration of arsenic was 1.64, 2.37, and 2.0 times higher than the maximum level for Treatments 2, 3, and 4, respectively. However, these treatments showed symptoms of several nutrient deficiencies and lower yields. Diluted PHWW supplemented with hydroponic fertilizer had lower yields than hydroponic fertilizer alone, indicating the PHWW may be inhibiting the lettuce growth in some way outside of nutrient availability. Therefore, this research provides evidence that lettuce grown with treated PHWW does not pose a biological contamination risk but may cause levels of arsenic that are in excess of safe levels if not properly supplemented with other fertilizers. PHWW is a potential source of nitrogen-rich fertilizer for lettuce production, though additional research of PHWW is necessary to improve NO3+NO2 concentrations and optimize fertilizer supplementation.

Graduation Semester

2019-05

Type of Resource

text

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http://hdl.handle.net/2142/104923

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Copyright 2019 Samuel Jesse

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