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Wet Waste

Conversion of Wet Waste to Fuel and Value-Added Products using Hydrothermal Carbonization

The Wet Waste project focuses on developing economic and sustainable pathways for the treatment and valorisation of food waste in India.

Grant: £148k DST-UKIERI funded
Dates: April 2019 – March 2021 (2 year project)

Principal investigator: Dr Andrew Ross, University of Leeds (UoL)

Indian lead partner: Prof Anurag Garg, Indian Institute of Technology Bombay (IIT)

Project team:

  • Ms. Divya Gupta, Centre for Environmental Science and Engineering, IIT
  • Mr Aaron Brown, School of Chemical and Process Engineering, UoL
  • Mr Nick Davison, School of Chemical and Process Engineering, UoL

Project partner: Indian Institute of Technology Bombay, India

Background

Total amount of food wasted globally throughout the supply chain from production to
consumption amounts to 1.3 billion tonnes. Organic waste in India forms 40-70% of the
MSW. Anaerobic degradation of waste contributes to 18% of the global anthropogenic
methane emissions. Energy recovery from the organic fraction of waste can provide an
alternative energy source along with reducing the waste volume. Hydrothermal
carbonization (HTC) is ideally suited to high moisture content waste and produces a 'coal
like' product called hydrochar within a matter of hours with an increased calorific value
(up to 30 MJ/kg) and reduced slagging and fouling tendency. The other main product is
an Aqueous stream which contains soluble organic and inorganic species. This
aqueous stream can be processed by anaerobic digestion resulting in a zero waste
biorefinery approach.

We propose HTC as a decentralized conversion route for wet waste. The calorific value
of hydrochar has been found to be high (20-30 MJ/kg) in several studies, however, the
temperature (180 - 350°C) and residence time (20 min – 20 h) vary widely. Based on
previous work conducted by the UK and Indian partners, we propose to prepare high
quality hydrochar using shorter reaction times (1-5 h) and lower temperatures (~200°C).
Moreover, the reuse and recovery of products from process water, not extensively
studied in the literature will be investigated such as recovery of proteins, humic acids,
and value added chemicals. We will also study the potential energy recovery from
product streams such as the combustion properties of the chars, their use as adsorbents
and application in agriculture and the generation of biogas from the process waters. The
socioeconomic impacts of HTC implementation and the environmental benefits,
including a full life cycle analysis of different conversion routes will be performed..

Aims

The primary aim of the project is to develop economic and sustainable pathways for the
treatment and valorisation of food waste in India. Specific goals include the production of
bio-energy, bio-products and chemicals using innovative routes capable of processing
wet waste with varying composition. Of particular interest is an emerging technology
called hydrothermal carbonisation (HTC) which has potential for producing a range of
products including a solid carbonaceous hydrochar and an aqueous stream rich in
organic carbon and inorganics.

Objectives

The specific objectives of the project include:

  1. Assessment of HTC for the production of bioenergy via thermochemical and
    biological conversion of the product streams (e.g. production of solid, liquid and gaseous
    biofuels)
  2. Assessment of HTC for the production of chemicals and bio-products via direct or
    upgrading of product streams ( e.g. adsorbents, humic substances, platform chemicals)
  3. Assessment of the environmental and technoeconomic benefits of using HTC for
    treatment of wet wastes in India.