Ramaprasad Majumder
Department of Forest and Ecosystem Science
The University of Melbourne, Burnley Campus
500 Yarra Boulevard, Richmond, VIC 3121, Australia
Mobile: 0421 765 362
Email: r.majumder@pgrad.unimelb.edu.au
Degree
PhD
Thesis title
Sustainability of phytoremediation of contaminated biosolids.
Supervisors
Dr Stefan Arndt
Dr Steve Livesley
Dr Scott Laidlaw
Project Outline
Biosolids are produced as by-products of sewage collection and treatment processes of any wastewater treatment plant. The amount of these biosolids is gradually increasing due to growing population.
Biosolids that are free of contaminants are commonly used as fertilizers or substrates in agriculture. However, some treatment plants produce biosolids that are contaminated with heavy metals and the use of these biosolids is limited which causes environmental concern. In the Western Treatment Plant at Werribee, for example, the majority of biosolids stockpiles is contaminated with heavy metals and can therefore not be applied to agricultural land.
One potential use for contaminated biosolids is to use them as a substrate for heavy metal tolerant plants, a process called phytoremediation. Phytoremediation of heavy metal contaminants can be achieved either through immobilizing the metals in a substrate (phytostabilisation) or by cleaning up by plant uptake (phytoextraction).
The sustainability of phytoremediation of contaminated biosolids has not been investigated in detail and is the main objective of this project. The research will be carried out to address the following objectives and research questions:
Objective 1: The effectiveness of plants to stabilize or reduce the heavy metal content of biosolids.
- What are effective plants species in Australia that can be used for phytostabilisation or phytoextraction?
- Can potential candidate species with multiple benefits (i.e. product can be sold on) be grown in biosolids without irrigation?
- Do they stabilize heavy metals or do certain plants mobilize heavy metals due to root exudation and soil acidification processes?
Objectives 2: Assessment of the potential environmental costs and benefits that are associated with a phytoremediation system.
- What is the real greenhouse gas balance of a phytoremediation system? I.e. carbon sequestration versus carbon emission (increased soil respiration) and emission of non-CO2 greenhouse gases (nitrous oxide and methane)
- Do different species and different management systems (irrigation vs. non-irrigation) have a different greenhouse gas (GHG) balance?
- What are the putative environmental costs associated with biosolids preparation (drying and storage before they can be used for phytoremediation)?
Objectives 3: Life-cycle analysis (LCA) of biosolids use
- Perform a life cycle analysis of the monetary and environmental cost of a phytoremediation system.
- Compare different management scenarios for phytoremediation systems (irrigation, harvests vs. stabilization)
- Compare different potential end-uses for biosolids(storage, kiln burn, phytoremediation)
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