Water & Wastewater Treatment

TECHNICALLY SPEAKING 36 Water & Wastewater Treatment February 2014 wwtonline.co.uk in combination with conventional digestion and advanced digestion have all been modelled in this analysis. Cost of treatment Each model was used to derive the unit cost of treatment for the whole sludge processing train and unit cost of treatment adjusted for benefit, both independent of sludge throughput, for example, as £/tonne dry solids (£/tDS) of sludge processed. Each model also generated the sludge processing energy demand and energy generation, independent of sludge throughput, for example, kWh/tDS. The costs included: • Power • Carbon fees • Chemicals • Sludge disposal • Staffing • Services • The benefits available included: • Power import cost defrayed by in situ generation • Power exports, where generation exceeds total site demand • Renewable Obligation Credits (ROCs) • Reductions in carbon fees • Reduction in sludge disposal costs AER carbon emissions were based on the full-scale study of sewage sludge gasification by Takahashi in Japan in 2007, where gasifier emissions were found to be 55% of sewage sludge emissions under combustion in a fluidised bed incinerator. The power demand and generating potential of each of the options is presented in Figure 1. Power generation The AER options are able to generate more power than incineration options, which appears to be due to the greater electrical power generating efficiency associated with gasification and pyrolysis. When gasification is compared to pyrolysis, there is an advantage to pyrolysis for electricity generation associated with better syngas quality and quantity potential. In part, this may be attributed to a higher parasitic load for the gasification options examined. Taking this factor into account, gasification fares better when combined with digestion and especially with advanced digestion if a low carbon outcome is sought. Similar to combining incineration with digestion, the combined technologies maximise the low parasitic load of biological treatment, while using the brute force of incineration or gasification to release most of the remaining energy that digestion is unable to access. Gasification does this more efficiently than incineration, but also may produce a better outcome than the non-optimised AAD-gasifier system in this study. It has waste heat that could be used better than in this study in combination with AAD. This is a separate investigation that remains to be undertaken and reported on. Risk management The final unit cost of treatment (UCT) presented in figure 2 can only be secured if the operating risks underpinning them are adequately managed. If energy production recovery practice becomes sub-optimal, a UCT set as a target will not be maintained. The great advantage of Virtual Works based modelling is that the model can be used to describe the entire operational envelope associated with a UCT. This means that a UCT has context which can be presented to an operator, allowing them to manage the risks to attaining the UCT. For example the impact of changes in the primary settling tank (PST) removal efficiency or the impact of a lower dewatered cake DS concentration. Outcome Based on a MWH Virtual Works model for the fictitious Greendale WwTW, we found that advanced energy recovery (AER) by gasification offered better energy recovery prospects and lower operating costs than incineration when paired with digestion or advanced digestion. This appears to arise from the better overall energy balance from the non-combustion process. The range of gasification technologies available is large and at present we suspect that there are further synergies that can be derived for a digestion or advanced digestion/ gasification AER system, with regard to recovering heat for digester and/or thermal hydrolysis process heating. The second AER option, Pyrolysis, offers further advantages over the gasification options considered here. These arise from production of a better syngas product than gasification, favouring more effective gas engine/CHP power generation. For carbon footprint reduction, raw sludge pyrolysis or AER technology paired with AAD provides the best outcomes. Another tool that MWH has developed to help understand the impact of resource inflation is the Median Water model, based on a fictitious UK water company and associated asset base representing the median of all UK WASCs. Using this tool we have been able to value the operational saving returns arising from systematic deployment of the leading AER/combined AER solutions at the largest sewage treatment works and all sludge treatment centres. Taking a typical UK WASC, this represents at least £35M/yr. Clearly questions surround any new technology and application. However, notwithstanding the cost and competition for available capital, there is potential for advanced energy recovery technologies, certainly at some of the larger treatment plants with regional sludge treatment centres attached. We see a strong future for extracting maximum energy from wastewater, whilst also retaining facets of other benefits such as nutrient recovery. nnn Figure 1. Energy recovery potentials: power demand and generation per tDS sludge Figure 2. Cost and benefit scenarios modelled for imagined Greendale sewage treatment works 2012 MOVING ON UP Boost to professional development of water scientists Scientists working in the water sector can now enhance their professional and career development through a new licence awarded to the Institute of Water (IoW). The Science Council has awarded the licence that permits the IoW to register Chartered Scientists (CSci) in the culmination of a two-year programme working closely with Anglian Water, the Drinking Water Inspectorate and the Science Council. The licence was launched in December at the Science Council, where 14 of the first Chartered Scientists were presented with their certificates. The IoW already offers Chartered Engineer and Chartered Environmentalist registrations and the organisation says the addition of Chartered Scientist to this portfolio strengthens its position. Anglian Water's chief executive, Peter Simpson, said, "Improving individuals' professionalism is part of the Anglian Water journey to ensure that teams, including our scientists, achieve and are recognised for their high level of competence. Being chartered is a statement about where the individual is, but is not the end of the journey. It marks the start of a further commitment to remain up to date with knowledge and understanding." Scottish-based water treatment specialist Triogen, a branch of Degremont Technologies, part of the Suez Group, has appointed Tom Kelly as managing director. Kelly has been technical director for the last four years. In another move for Suez Group, Ondeo Industrial Solutions, part of Degremont Industry, has appointed two additional global business development managers - Jerome Nessi and John Meredith (pictured). Infrastructure and business services group Mouchel has appointed Ian Troughton to the new post of head of project management within the Mouchel Infrastructure Services (MIS) business as part of its preparations for a period of significant growth. Fleet management specialist Isotrak has appointed Jason Price as sales and marketing director as part of a push to expand global sales and expand into new markets including utilities. Appointments 37 Water & Wastewater Treatment February 2014 wwtonline.co.uk RECRUITMENT To advertise call Alyson Brice on 01342 332075 E: alyson.brice@fav-house.com alexander-assoc.co.uk Commissioning Coordinator & Mgr London & South Coast £40 to £50k Princ Civil Eng W & WW Netwks South East Up to £50k Civil Project Manager London £38 to £45k Electrical Design Engineer London & South East£32 to £35 Ltd Flood Risk River Modeling expert South West Perm £Neg MEICA Coordinator London & Surrey Up to £40 Ltd Civil Design Eng with 5-10 yrs exp S.East & West £35k/£25 to £28 Ltd MEICA Project Manager South East Up to £350 Ltd Proposals Engineer London & Mids Up to £35 Ltd Developer Services Manager South West Perm £Neg Process Design Engineer South East Up to £70k Mechanical Design Engineer SE & NW Up to £32 Ltd Environmental Consultant South East Perm £Neg Structural Engineer London Up to £48k Technical Author South East £170 to £190 Ltd Commercial Manager South East £75 to £100k Hydraulic Engineer/Surge Analyst East Anglia Perm £Neg Chemical Sales Engineer Midland Circa £35 to £42k In the current market we are not advertising all our contract roles.We are seeking CVs for all levels of MEICA, Process and Civil Engineers. CVs to: Ruth Parker, Alexander Associates 01959 562572 water@alexander-assoc.co.uk www.alexander-assoc.co.uk Project Engineer South East £30 to £40k Electrical Design Engineer North £30 to £42k Planner South East £Contract Project Controllers South East & Mids Up to £50k Civil Design Engineer North £25 to £33k Sales Support Engineer South East £ Perm Senior Network Engineer North Up to £35k Process Design Engineer Mids & North £Contract Mechanical Project Engineer South East c.£400ltd Technical Delivery Manager Anglian £ Perm Senior Network Engineer North £35k Product Sector Leader South East £ Perm Senior Mechanical Design Eng Mids Up to £30ltd Snr Wastewater Network Modeller South East £ Perm MEICA Project Manager Mids/Anglia c.£48k Design Leader (Civil/Mechanical) North £35 to 45k Product Engineer South East £ Perm Civil Design Engineer (All Levels) Mids Up to £33k We've got you covered Corporate Engineering is a specialist GRP Odour Control Cover manufacturer. Our products are used in a wide range of waste industries. Our expansion plans have created an exciting opportunity to further develop the sales of our product range. Vacancy: Sales Engineer (Southern Region) Salaried Position + Company Car Ideally located in the Thames Valley, suitable applicants will preferably come from wastewater background and have a minimum of 3 years' experience. Duties will include: • Meeting set targets and objectives • Manage and develop leads • Project identification • New business development A confident personality and an innovative approach is required. Knowledge of Microsoft office is a must. To apply please send CV to: David Walton – dave@grpcovers.com Closing date for applications is the 22 nd January 2014 Culham Mill Little London Road Silchester RG7 2PP • Competitive salary • Company car or car allowance • Annual holiday entitlement of 25 days + Bank holidays Please forward C.V. by email to Mr David Walton, Sales Manager, d.r.walton@btconnect.com Corporate Engineering is a specialist GRP Odour Control Cover manufacturer. Our products are used in a wide range of waste industries. Our expansion plans have created an exciting opportunity to further develop the sales of our product range. Vacancy: Sales Engineer (Southern Region) Salaried Position + Company Car Ideally located in the Thames Valley, suitable applicants will preferably come from wastewater background and have a minimum of 3 years' experience. Duties will include: • Meeting set targets and objectives • Manage and develop leads • Project identification • New business development A confident personality and an innovative approach is required. Knowledge of Microsoft office is a must. To apply please send CV to: David Walton – dave@grpcovers.com Culham Mill Little London Road Silchester RG7 2PP WWT feb 14 classi pages.indd 37 21/01/2014 11:19 The first 14 Chartered Scientists registered by the Institute of Water join regulators and Anglian Water chief executive Peter Simpson at a special Science Council event

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