Case Studies and Clients

This job, with a wide-ranging scope and extending over a three-year period, began with a survey of technologies applicable to small-scale surface water treatment for potable water supply. Of particular concern was suppression of chlorinated organic byproduct formation along with reduction of the risk of microbial contamination, and cryptosporidium oocysts in particular. Part of the study entailed a review of membrane integrity test methods and patterns of behaviour in historical oocyst detection.

Another major part of the work was a review of pilot/full-scale demonstration of membrane technologies for THM formation abatement with reference to: (a) the rejection of natural organic matter and its discrete constituents (b) the reactivity of the residual organic matter with reference to THM formation, and (c) the membrane hydraulic performance in terms of the sustainable permeability. The work culminated in a practical demonstration-scale study of the short-listed candidate NF technologies.

This work informed a paper, published in 'Separation and Purification Technology', on the THM formation propensity of residual natural organic matter in ultrafiltration permeate streams, data being taken from 35 regional UF plants challenged with surface water.

A change in international marine legislation prompted the client to fund a comprehensive review of commercially-available and developing technologies for the treatment of ballast water. The review entailed one-to-one interviews with global technology providers (from the Far East to North America) to ascertain the status of their technology, with particular reference to the approval process, along with an assessment of their likely efficacy in meeting the required treated water quality. The outcomes were published in a document published by the client in 2007 ('Ballast water treatment technology: current status') and updated in 2012 ('Ballast water treatment technologies and current system availability').

This job entailed identifying the most practical and low-cost option for managing a newly-generated industrial effluent at a site in the north west of England. The effluent was being treated using a DAF plant, the performance and running costs of which were appraised as part of the remit. The scope included an assessment and costing of short-term options for aerobic treatment of both the raw and DAF-treated effluent for sewer discharge vs. tankering based on information provided by the client and available data on biological treatment plant costs. The primary output was a cost analysis spreadsheet evaluating the cost benefit of the preferred option, and specifically the value provided by the dewatering of the waste sludge prior to disposal.

The assessment of offshore produced water treatment installations was carried out for a client based in the Arabian Gulf. The job demanded the performance of the technologies to be benchmarked against that reported for other installations, primarily in the grey literature and conference presentations. The work culminated in the publication of a review of the treatment performance and footprint of PW treatment technologies, with the focus being on tertiary treatment by filtration for reinjection (PWRI), published in 'Separation and Purification Technology'.

This job entailed the assessment of the design and O&M details to try and overcome a challenge imposed by severe permeability decline following a CIP (clean-in-place) at a small (~2,000 m³/d capacity) plant in Scotland. Two site visits and a number of communications with the client revealed that the recirculation rate through the membrane tank was too low for one of the plants, causing concentration polarisation problems, coupled with a strong clogging and ragging tendency. The ragging challenge was met by installing a rudimentary screen on the RAS. A second smaller plant (~400 m³/d capacity) was subject to severe fluctuations in water quality, demanding equalisation.

The cause of ragging generally was subsequently identified in a separate research project, the outcomes of which were published in the 'Journal of Membrane Science'. This paper was the first research paper published which analysed and quantified ragging in MBRs, as well as identifying the root cause.

This job involved assessment of the design and O&M data of a large (>50,000 m³/d capacity) MBR plant in the UAE for which the CIP was failing to recover the permeability. Clogging was evident at this site, and an examination of permeability trends at other MBRs in the region revealed that they were subject to the same problem. Through benchmarking against other sites subject to the same general climatic conditions, it was demonstrated to the client that the design fluxes were overly ambitious and that additional membrane area was needed.

For this job, the basic design parameters for a large municipal MBR (>250,000 m³/d capacity) were required given very strict spatial limitations and a cold climate. It was demonstrated, through determination of net packing densities (taking account of both the in-module packing density and the spacing between the cassettes in the tank) that the options were limited to an HF iMBR (hollow fibre immersed MBR) technology, with appropriate O&M conditions identified from comparable existing large municipal WwTPs.

This job entailed identifying existing MBRs used for petrochemical effluent treatment (~40,000 m³/d capacity), along with their reported design and O&M. Evidence was provided to demonstrate the feasibility of the technology for the application envisaged, specifically with reference to the feed water quality. Performance data (COD removal and sustainable net flux) from other full-scale plants was acquired and collated to identify the most appropriate design and optimum O&M conditions. Specific comparable sites were identified for planned site visits.

The work concerned the review of the status of existing assets and the options for their refurbishment or replacement at two wastewater treatment works in a remote island location. The work involved a site visit to assess the operational state of the assets along with reports of treatment objectives (which included reuse of the reclaimed water for irrigation purposes), process options and their commercial status, projected performance and overall costs determined as the net present value. Reuse was found to provide a significant cost benefit due to the high cost of potable water supply from seawater desalination.

This job entailed a review of the design criteria and proposed operation and maintenance protocols for a large municipal wastewater treatment installation in Oman. The work included an assessment of the likely integrity of the membranes, which had been stored for an extended period of time prior to their installation. It was concluded that the storage period and conditions were unlikely to impact significantly on membrane integrity. A four-day short course on MBRs tailored to the client's needs and delivered to the operators, was provided as part of the job.

The work concerned an incident of temporarily impaired potable water supply from a UK water utility which resulted in prosecution by the UK water regulator. Extensive review of the literature was required to establish mitigating circumstances, and that the most appropriate remedial measures were undertaken by the water utility facing the challenge. This was used to provide a robust defence during court proceedings.

The main objective of this project was to identify a simple and low-cost process technology for abatement of nitrate in groundwater for potable water supply. The work entailed an extensive search of the research literature followed up with face-to-face enquiries with relevant workers in the field to establish the logistics, practical feasibility and overall relative costs of the various technical solutions identified. This then led to the planning of a pilot-scale development project designed to assess the efficacy of the most promising technology.

Assistance with the management of a research project concerning the hydrothermal carbonisation of sludge. The work, which was being conducted at both laboratory and pilot scale, included appraising the outputs from the project along with a survey of relevant supporting literature and related commercial developments within the area. Of particular interest was the fate and potential recovery of phosphorus from the process, specifically in a form reusable as an agrochemical.

A number of market surveys and/or cost analyses have been conducted for various international clients based in North America and northern Europe, either planning or in the early stages of commercialising new MBR technologies or related products. These have tended to focus on an analysis of other comparable technologies for general or specific applications, as well as in two cases a review of the membrane material itself.