Professor Colin Hills

Professor Colin Hills BSc, MSc, PhD, DIC, FGS, FRSC, CSci

Professor in Environment and Materials Engineering

Key details

Professor Colin D Hills

Professor in Environment and Materials Engineering

Professor Colin Hills is Professor of Environment and Materials Engineering and Director of the Centre for Contaminated Land Remediation at University of Greenwich. He has been actively involved in research and development of stabilisation/solidification (s/s) systems for more than 25 years. His work includes national guidance on s/s of contaminated soil for the Environment Agency (England and Wales), and the development of novel s/s systems. He has received a number of national prizes, including the IChemE Green Chemical Technology Award, the national Shell Springboard prize, and the Times HE Award for his outstanding contribution to Innovation and Technology.

Professor Hills’ work on the beneficial re-use of waste CO2 gas in the treatment (by carbonation) of contaminated soil and waste has resulted in the first commercial production of artificial aggregates. The aggregates were awarded the UK’s Best Recycled Product for 2013, and are used in the world’s first ever carbon negative building block, manufactured by Ligancite in Suffolk.

Professor Hills is a Founder Director of both Carbon8 Systems and Carbon8 Aggregates, spin-out companies of the University of Greenwich.


Professor Hills studied Geology (BSc) and Industrial Petrology (MSc) at Queen Mary College, London. His PhD (Imperial College) in environmental engineering followed a period working as a field geologist in the Middle East and West Africa (Stanger, Intersite, Nigeria Dredging and Marine), and in process technology and engineering for Redland (now Lafarge). Professor Hills joined the University of Greenwich as a Senior Research Fellow in 1998, and was appointed Reader in 2002.

Responsibilities within the university

Teaching and administrative activities

  • Course co-ordinator for Practical and Professional Skills for Environmental Scientists and Geographers and (L4) and Environmental Management (L5). Both courses are designed to teach fundamental field- and laboratory-based skills to provide an awareness of the importance and impact of environmental science to our wellbeing.
  • Delivers the engineering geology provision into the School of Engineering (including a long field-based trip to the Devon), and contributes to the MSc Environmental Conservation programme.
  • Postgraduate Tutor for the School of Science and actively involved with ERASMUS Mundus.

MPhil/PhD supervision

  • Paris Araizi
  • Gabor Dallos.


  • The IChemE Green Chemical Technology Prize (2006)
  • The Kent Environment Award (2007)
  • Kent Innovation Challenge (2007)
  • National Winner of the Shell Springboard Challenge (2008)
  • The Times Higher Award for Outstanding Contribution to Innovation and Technology (2010)
  • UK Recycled Product of the Year (2013).


  • Fellow of the Geological Society of London
  • Member of the Institute of Materials, Minerals and Mining
  • Member of the European Science Foundation Review Panel (2006-present).
  • Long-standing member of ISCOWA and the Society of Chemical Industries
  • Co-chair of the Kent and Medway Contaminated Land Forum, and organiser of the twice-yearly Soils in the SE Workshop, which attracts >100 delegates to Medway.
  • Past Chairman, Cement and Concrete Group, Institute of Materials (IoM3) and past member of the EPSRC Peer review panel (2000-2012).
  • Founder and long-serving member of the scientific and organising committee of ACEME
  • Active member of ISCOWA and WASCON
  • Co-Chair of the International Stabilisation/Solidification Technology Forum held in Canada in June 2010.
  • Guest Editor for the International Journal of Environmental Technology and Management and regular reviewer for a number of International Journals including:
    • Environmental Science and Technology
    • Waste Management
    • Journal of Hazardous Materials and Waste and Resource Management.

Research / Scholarly interests

Dr Hills' current research interests include the application of carbon dioxide gas to treat soil and waste to produce materials that are fit for use in the construction industry. The valorisation of waste streams in this way has involved working with, for example, Shell, BP, Viridor, Grundon and a number of KTNs, including CO2 Chemistry.

Activities include

  • Treatment of soil washing residues (Roberta Maffettone, University of Salerno)
  • Investigation of MSW APCr (Josepha Parel, University of Rennes)
  • Novel calcium silicate-based sorbents (Jelena Tricovic, University of Novi Sad)
  • Carbonation of brucite (Mineralisation Cluster, CO2Chem KTN, and Carbon8)
  • Carbonation of steel slag (Tata Steel; ArcelorMittal)
  • Treatment of cement manufacturing residues (CEMEX).

Key funded projects

Sustainable Aggregate Production with Imbibed CO2 (SAPICO2): 2013 - 2015

Partners: University of Greenwich (lead), University of Picardie, Carbon8 Systems
Funder: Interreg IV A (Channel Programme), with a value of ≈ €900,000

SAPICO2 is a collaborative project to investigate carbonate-able waste streams in France and the UK for their incorporation into new materials. Project outcomes involve the production and performance evaluation of new building materials for use in construction.

Passify Project

Lead Partner: University of Greenwich

The Passify Project (Performance Assessment of Stabilised/Solidified Waste Forms) investigated the long-term effectiveness of stabilisation/solidification (s/s) of contaminated soil based on:

  • The extraction of field samples taken from full-scale application of s/s technology in the USA, France and UK
  • The identification of risk indicators in a detailed program of chemical, physical and microstructural testing.

The core partners were the University of Greenwich, University of New Hampshire and INERTEC. CLA:IRE, The Welsh Assembly, the PCA, SITA Environmental Trust and Environmental Geotechnics Ltd. were key funding agencies supporting the investigation.

The US Environmental Protection Agency, The Environment Agency and ADEME were key partners in allowing remediated contaminated sites to be invasively investigated. The University of Birmingham, University of Cranfield, The Royal Engineers.

Passify was awarded Eureka Status (S!3308), by the European Union.

The following main tasks were carried out including on samples taken from Superfund sites in the USA:

  • Clarification of the history of use of each site
  • Determining site characteristics and identifying pollutant pathways
  • Sampling and performance testing
  • Long term behaviour studies (ENV 12920)
  • Results interpretation, reporting and dissemination.

Passify project report.

Recent publications


Hills, Colin , Tripathi, Nimisha, Carey, Paula (2021), Managed pathways for CO2 mineralisation: analogy with nature and potential contribution to CCUS-led reduction targets. Royal Society of Chemistry (RCS). In: , , , . Royal Society of Chemistry (RCS), Faraday Discussions, 230 . pp. 152-171 ISSN: 1359-6640 (Print), 1364-5498 (Online) (doi: NB Item availability restricted.

Hills, Colin D. , Tripathi, Nimisha, Singh, Raj S., Carey, Paula J. , Lowry, Florence (2020), Valorisation of agricultural biomass‑ash with CO2. Nature Research. In: , , , . Nature Research, Scientific Reports, 10: 13801 2045-2322 (Online) (doi:

Tripathi, Nimisha , Hills, Colin D., Singh, Raj S., Singh, Jamuna S. (2020), Offsetting anthropogenic carbon emissions from biomass waste and mineralised carbon dioxide. Nature Publishing Group. In: , , , . Nature Publishing Group, Scientific Reports, 10: 958 2045-2322 (Online) (doi:

Tripathi, Nimisha , Hills, Colin, Singh, Raj S, Atkinson, Christopher J. (2019), Biomass waste utilisation in low-carbon products: harnessing a major potential resource. Nature Research. In: , , , . Nature Research, npj Climate and Atmospheric Science, 2: 35 2397-3722 (Online) (doi:

Ajibade, Oluwatoyin Opeyemi , Tota-Maharaj, Kiran, Hills, Colin, Macleod, Cecilia (2019), Modelling of a sustainable refugee camp drainage system for storm water management. Royal Society of Chemistry. In: , , , . Royal Society of Chemistry, Environmental Science Water Research & Technology, 5 (12) . pp. 2150-2161 2053-1400 (Online) (doi:

Choi, Hun , Lake, Craig B., Hills, Colin. (2019), Particle size effects on breakage of ACT aggregates under physical and environmental loadings. American Society of Civil Engineers (ASCE). In: , , , . American Society of Civil Engineers (ASCE), Journal of Hazardous, Toxic, and Radioactive Waste, 24: 4019029 (1) ISSN: 2153-5493 (Print), 2153-5515 (Online) (doi:

Monrose, John , Tota-Maharaj, K., Mwasha, A., Hills, C. (2019), Effect of carbon-negative aggregates on the strength properties of concrete for permeable pavements. Taylor & Francis. In: , , , . Taylor & Francis, International Journal of Pavement Engineering, 21 (14) . pp. 1823-1831 ISSN: 1029-8436 (Print), 1477-268X (Online) (doi:

Tripathi, Nimisha , Singh, Raj S., Hills, Colin D. (2018), Microbial removal of sulphur from petroleum coke (petcoke). Elsevier. In: , , , . Elsevier, Fuel, 235 . pp. 1501-1505 ISSN: 0016-2361 (Print), (doi: NB Item availability restricted.

Tripathi, Nimisha , Choppala, Girish, Singh, Raj S., Hills, Colin D. (2017), Impact of modified chitosan on pore water bioavailability of zinc in contaminated soil. Elsevier. In: , , , . Elsevier, Journal of Geochemical Exploration, 186 . pp. 94-99 ISSN: 0375-6742 (Print), (doi:

Tripathi, Nimisha , Hills, Colin D., Singh, Raj S., Carey, Paula J. (2017), Construction: use waste for building. Nature Publishing Group. In: , , , . Nature Publishing Group, Nature, 550 (457) ISSN: 0028-0836 (Print), 1476-4687 (Online) (doi:

Lei, Ming , Peng, Liang, Tie, Baiqing, Liao, Bohan , Hills, Colin D. , Song, Zhengguo , Tang, Zhen (2017), Effect of mineral-based amendments on rice (Oryza sativa L.) growth and cadmium content in plant and Polluted soil. Mary Ann Liebert. In: , , , . Mary Ann Liebert, Environmental Engineering Science ISSN: 1092-8758 (Print), 1557-9018 (Online) (doi:

Kucsh, Sigrid and , Hills, Colin (2017), The link between e-waste and GDP—new insights from data from the pan-European region. MDPI. In: , , , . MDPI, Resources, 6: 15 (2) ISSN: 2079-9276 (Print), 2079-9276 (Online) (doi:

Lake, Craig , Choi, Hun, Hills, Colin D., Gunning, Peter , Manaqibwala, Idris (2016), Manufactured aggregate from cement kiln dust. Institution of Civil Engineers. In: , , , . Institution of Civil Engineers, Environmental Geotechnics . pp. 1-12 2051-803X (Online) (doi:

Ngene, Stanley , Tota-Maharaj, Kiran, Eke, Paul, Hills, Colin (2016), Environmental and economic impacts of crude oil and natural gas production in developing countries. Science Publishing Group. In: , , , . Science Publishing Group, International Journal of Economy, Energy and Environment, 1 (3) . pp. 64-73 (doi:

Jamshidi, Reza Jolous , Lake, Craig B., Gunning, Peter, Hills, Colin D. (2016), The effect of freeze/thaw cycles on the performance and microstructure of cement-treated soils. American Society of Civil Engineers. In: , , , . American Society of Civil Engineers, Journal of Materials in Civil Engineering, 28 (12) ISSN: 0899-1561 (Print), 1943-5533 (Online) (doi:

Tripathi, Nimisha , Singh, Raj S., Hills, Colin D. (2016), Soil carbon development in rejuvenated Indian coal mine spoil. Elsevier. In: , , , . Elsevier, Ecological Engineering, 90 . pp. 482-490 ISSN: 0925-8574 (Print), (doi:

Araizi, Paris K. , Hills, Colin D., Maries, Alan, Gunning, Peter J. , Wray, David S. (2016), Enhancement of accelerated carbonation of alkaline waste residues by ultrasound. Elsevier. In: , , , . Elsevier, Waste Management, 50 . pp. 121-129 ISSN: 0956-053X (Print), (doi:


Tripathi, Nimisha , Singh, Raj S., Hills, Colin D. (2016), Reclamation of Mine-impacted Land for Ecosystem Recovery. Wiley-Blackwell. In: , , , . Wiley-Blackwell, UK (1st) . ISBN: 9781119057901 (doi:

Conference proceedings

Tota-Maharaj, Kiran , Hills, Colin, Cheddie, Denver (2017), Low cost urban wastewater infrastructure for environmental sustainability across Caribbean small island developing states (SIDS). Allied Publishers PVT. LTD. In: , , In: P. K. Singh, V. K. Singh, A. K. Singh, D. Kumbhakar, M. P. Roy (eds.), NexGen Technologies for Mining and Fuel Industries (NxGnMiFu-2017). Allied Publishers PVT. LTD, New Delhi, India . pp. 697-705 . ISBN: 9789385926402 (doi:

Tota-Maharaj, Kiran , Monrose, John, Hills, Colin (2017), Novel permeable pavement systems utilising carbon-negative aggregate. Allied Publishers PVT.LTD. In: , , In: P. K Singh, V. K Singh, A. K Singh, D. Kumbhakar, M. P Roy (eds.), NexGen Technologies for Mining and Fuel Industries (NxGnMiFu-2017). Allied Publishers PVT.LTD, New Delhi, India (1st) . pp. 683-696 . ISBN: 9789385926402 (doi:

Hills, Colin , Aliyu, Musa, Chen, Hua-Peng, Harireche, Ouahid (2017), Numerical modelling of geothermal reservoirs with multiple pore media. Stanford University. In: , , , Proceedings 41st Workshop on Modelling on Geothermal Reservoir Engineering. Stanford University, (doi: ).

Carey, Paula and , Hills, Colin (2017), Development of the first commercial use of mineral carbonation: treating waste using accelerated carbonation to manufacture an aggregate. Allied Publishers Pvt. Ltd. In: , , In: Pradeep K. Singh, V. K. Singh, A. K. Singh, D. Kumbhakar, M. P. Roy (eds.), NexGen Technologies for Mining and Fuel Industries (Volume I and II). Allied Publishers Pvt. Ltd, New Delhi . pp. 1003-1008 . ISBN: 9789385926402 (doi: ).

Hills, Colin , Carey, Paula, Tripathi, Nimisha (2017), Opportunities of CO2mineralisation in Indian waste-based manufactured products. Allied Publishers Pvt Ltd. In: , , In: Pradeep K. Singh, V. K. Singh, A. K. Singh, D. Kumbhakar, M. P. Roy (eds.), NexGen Technologies for Mining and Fuel Industries (Volume I and II). Allied Publishers Pvt Ltd, New Delhi . pp. 1105-1112 . ISBN: 9789385926402 (doi: ).

Singh, Raj S. , Chaulya, Swadesh, Tripathi, Nimisha, Hills, Colin D. (2017), Revegetation as a tool for mine spoil carbon recovery and dump stability. Allied Publishers Pvt. Ltd. In: , , In: Pradeep K. Singh, V. K. Singh, A. K. Singh, D. Kumbhakar, M. P. Roy (eds.), NexGen Technologies for Mining and Fuel Industries (Volume I and II). Allied Publishers Pvt. Ltd, New Delhi . pp. 895-908 . ISBN: 9789385926402 (doi: ).

Tripathi, Nimisha , Hills, Colin D., Gunning, Peter, Singh, Raj S. (2017), Mineralisation of CO2 in wastes for Indian climate change. Allied Publishers Pvt Ltd. In: , , In: Pradeep K. Singh, V. K. Singh, A. K. Singh, D. Kumbhakar, M. P. Roy (eds.), NexGen Technologies for Mining and Fuel Industries (Volume I and II). Allied Publishers Pvt Ltd, New Delhi . pp. 1129-1138 . ISBN: 9789385926402 (doi: ).

Tripathi, Nimisha , Hills, Colin D., Choppala, Girish, Singh, Raj S. (2017), Modified chitosan for contaminated soil remediation. Allied Publishers Pvt Ltd. In: , , In: Pradeep K. Singh, V. K. Singh, A. K. Singh, D. Kumbhakar, M. P. Roy (eds.), NexGen Technologies for Mining and Fuel Industries (Volume I and II). Allied Publishers Pvt Ltd, . pp. 835-848 . ISBN: 9789385926402 (doi: ).

Edited book

Hills, Colin and , (2016), Global Environment Outlook GEO-6: Assessment for the Pan-European Region. UNEP. In: , , , . UNEP, Nairobi, Kenya . ISBN: 9789280735451. (doi: ).