Veolia (United Kingdom)

At Beach Energy’s Otway Gas Plant (OGP) the mono-ethylene glycol (MEG) system salt concentration increased significantly following the commissioning of new subsea horizontally completed wells. Therefore, to de-risk future developments, which are anticipated to include similar wells, a salt removal strategy was implemented. The use of MEG for gas hydrate suppression in wet-raw gas subsea or onshore production pipelines is common across the oil and gas industry, with the MEG recycled using well-proven regeneration and/or reclamation technologies. The MEG extracts water that can contain residual salt and minerals, which over time accumulate in the MEG and can lead to several operational issues, including severe fouling in the MEG regeneration plant, production line blockages and production pipeline integrity concerns, such as accelerated corrosion. MEG reclamation is used to minimise salt accumulation and to date, the dominant technologies employed have been vacuum distillation or flash vaporisation. However, since early 2022, electrodialysis (ED) membrane technology has been deployed at the OGP in an effort to find a more cost-effective solution. The technology is proving a viable alternative to a traditional vacuum distillation reclaiming–regeneration process with energy savings of 17–28% for a hybrid ED-Regeneration process with significantly lower capital cost. This paper details the technical and operational challenges overcome to implement the ED reclamation technology in an industry with more stringent regulatory requirements when compared to typical ED applications (e.g. within the water treatment, pharmaceutical, and food and beverage industries), as well as present the main system performance outcomes following 6 months of operation.

Water treatment is a series of physio-chemical processes to aid organic matter (OM) removal, which helps to minimise the formation of potentially carcinogenic disinfection by-products and microbial regrowth. Changes in OM character through the treatment processes can provide insight into the treatment efficiency, but radiogenic isotopic characterisation techniques have yet to be applied. Here, we show for the first time that analysis of 13C and 14C of dissolved organic carbon (DOC) effectively characterises dissolved OM through a water treatment works. At the sites investigated: post-clarification, DOC becomes isotopically lighter, due to an increased proportion of relatively hydrophilic DOC. Filtration adds ‘old’ 14C-DOC from abrasion of the filter media, whilst the use of activated carbon adds ‘young’ 14C-DOC, most likely from the presence of biofilms. Overall, carbon isotopes provide clear evidence for the first time that new sources of organic carbon are added within the treatment processes, and that treated water is isotopically lighter and typically younger in 14C-DOC age than untreated water. We anticipate our findings will precipitate real-time monitoring of treatment performance using stable carbon isotopes, with associated improvements in energy and carbon footprint (e.g. isotopic analysis used as triggers for filter washing and activated carbon regeneration) and public health benefits resulting from improved carbon removal.

The European Commission is tightening waste laws, and many local authorities, particularly in countries with low recycling rates, face the question of what system to introduce for the source-separate collection of food waste from householders. This study provides empirical data in form of fuel consumed and waste yield from four councils that already have source separate organic waste collections in operation. Two systems were compared: (1) door-to-door collection and (2) bring systems where the householder walks to the bin in her/his street to drop off organic waste. Fuel consumption for the collection operation with the bring system was dramatically lower compared to the door-to-door system. Organic waste yield was constant over the observation year in the door-to-door system employing small 20- to 30-l bins, but increased notably in the summer with the bring system that used 240-l bins. The metric used to quantify seasonality was the summer/winter yield ratio. As commercial waste companies do not normally allow the making of data public, this is a rare opportunity to learn from collection systems currently in operation.