Onsite anaerobic treatment of aquaponics lettuce waste: digestion efficiency and nutrient recovery

Ze Zhu, Uri Yogev, Karel J. Keesman, Amit Gross*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

Abstract

Aquaponics plant waste, such as the non-edible parts of many vegetable crops, can be a source of environmental pollution, while its treatment might cause an economic burden. Therefore, efficient use of this waste would be advantageous. This study aimed at investigating anaerobic digestion of aquqponic lettuce waste to recover nutrients and energy through biogas production. A 700 L commercial anaerobic system was used to treat lettuce wastes from an aquaponic farming system that operated under desert climate and steady-state conditions. Digestion efficiency of the lettuce waste was 90.1% by weight, producing a maximum biogas volume of 0.65 m3/kg dry weight per day. Biogas composition contained on average 59.2% methane and 38.9% CO2 with only negligible hydrogen sulfide content. Moreover, the supernatant from the anaerobic digester contained elevated nutrient concentrations (N, P, K, Ca, and Fe), which can potentially be used onsite as a fertilizer. Onsite anaerobic digestion of lettuce plant waste from the aquaponic system under summer desert conditions is demonstrated for the first time to efficiently reduce pollution burden, produce high-quality biogas, and recover nutrients.
Original languageEnglish
JournalAquaculture International
DOIs
Publication statusE-pub ahead of print - 1 Oct 2020

Keywords

  • Anaerobic digestion
  • Aquaponics
  • Bioenergy recovery
  • Desert farming
  • Nutrient reuse
  • Waste management

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