PhD position on flocculation in plumes

Updated: about 1 month ago
Deadline: 12 Aug 2021

The potential of deep-sea mining for metalliferous sediments, massive sulphides and poly-metallic nodules is presently explored by industries and academics. Manoeuvring, excavating and processing will generate plumes of suspended fine-grained solids, considered harmful to the deep-sea environment due to their potential of smothering and burying benthic fauna. To assess the impact it is essential to determine how far plumes are dispersed by bottom currents and how their suspended loads evolve with time. Numerical simulations used to predict the dispersion of mining plumes are likely overestimating the impacted area, as they do not take flocculation of fine particles into larger, faster-sinking aggregates into account

Flocculation is a process that is not well understood, and neither is the extent in which it affects plume dispersion. Adding up to uncertainty, current methods for in-situ monitoring of turbid plumes make use of optical and acoustic sensors sensitive to particle size, yet flocculation is not taken into account. Consequently, plume monitoring results may be significantly in error.

In this PhD position you will work on developing state-of-the-art experimental and analytical tools in order to establish a link between the mining equipment and the dynamics of the plume dispersion. The experiments to be conducted will be on large scale laboratory setups. Turbidity currents can be studied in a lock-exchange, while plume fully coupled plume dispersion experiments are to be conducted within a large flume. Within these experiments, the emphasis will be on how to influence the flow properties of cohesive sediment, aiming at minimal of said sediment plumes.

As a PhD-candidate, you will be part of a vibrant team of researchers in the PLUMEFLOC consortium. There is a strong collaboration going on with research teams from the environmental fluid mechanics department at TU Delft, they focus on micro-scale characterisation of the behavior of the cohesive sediment, and with Ocean Systems at the Dutch Sea Research Insitute (NIOZ), who will focus on measuring and characterizing sediment plumes and flocculation in the field. You will be supervised by Assistant Professor Rudy Helmons and Professor Cees van Rhee from the Submerged and Seabed Systems group. Here the research focuses on a pragmatic and fundamental approach to address the complex multiphysics processes related to dredging, mining and offshore equipment.

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