Bigger, better, bioreactor…

Membrane bioreactors are getting bigger and bigger. Aqualia's Frank Rogalla crunches the numbers, revealing that in China the use of MBRs is blossoming

Ever since Cranfield University published its first book on membrane bioreactors (MBRs) in 2000, this process has been a hot topic in wastewater treatment and reuse – the fourth version of the book authored by the School of Water Sciences is being released this month. In Spain, MBRs have been used since 2004, first on smaller scale for reuse and irrigation, such as a handful of plants in the range of 1000m3/d in the Canary Islands.

However, since 2007, the MBR plant in Sao Pedro de Pinatar near Murcia can claim to be Europe’s biggest, treating an average capacity of 20,000m3/d and with a peaking factor of 2.4 on 48,000m2 of submerged hollow fiber membranes from GE Water/Zenon. In early 2009, work was started at the wastewater treatment plant (WWTP) of Gavà-Viladecans in Catalunya for an even larger MBR plant for a dry weather flow of 32,000m3/d, which will be half of the installed treatment capacity at the plant. Around the same time, a slightly larger system for 35,000 m3/d of reuse capacity with MBR was commissioned in Sabadell.

Also in Catalunya, Aqualia started up its 15,000m3/d MBR plant in Terrassa, and in 2010 obtained the order for expanding the Avila WwTP near Madrid with an MBR for an average capacity of 35,000m3/d and a peak factor of 1.8. Until 2007, the three largest MBR plants in the world were considered to be:

  • Nordkanal – operated by Erftverband near Duesseldorf in Germany, commissioned in early 2004 and treating around 16,000m3/d of average dry weather flow, but the installed 84,500m2 of hollow fibre membranes allow a wet weather capacity of almost three times higher
  • The highest dry weather flow capacity was installed in Brescia, Italy, with a constant flow of 41,640 m3/d, started up at the end of 2002
  • In the US, Traverse City in Michigan, with an average flow of 26,500m3/d and a peaking factor close to 2.5

Beyond the industrial applications and the race for ever larger systems, MBRs have been a priority on the research agendae in the past decade. The EC had co-financed about 60% of a cluster of four parallel projects in the last batch of the 6th framework programme from 2005 to 2009, bringing together around 50 European and international companies and institutions in an initiative valued at £12.7M:

  • MBR-TRAIN sponsored Marie Curie Fellowships for Early Stage Research Training with a budget of £1.75M and was co-ordinated by RWTH Aachen University, Department of Chemical Engineering. Its objectives were to enhance the intersectorial collaboration in an interdisciplinary field that is considered crucial for sustainable development, the field of water technologies, as well as to overcome the fragmentation within European research.
  • AMEDEUS was a Targeted Research Project under the priority theme Global Change & Ecosystems, supported by a EU subsidy of £2.5M as well as £170,000 from the Australian government and coordinated by the Berlin Centre of Competence for Water. The aim was to increase the competitiveness of MBR technology by reducing capital and operation costs, as well as environmental impact
  • EUROMBRA was supported by the EU in the same theme, with the same amount of £2.5M, complemented by £200,000M from Australian government, and was co-ordinated by the Norwegian University of Science & Technology in Trondheim. It targeted specific improvements of MBR technology, particularly the assessment and comparison of different configurations of membranes and membrane modules and the development of new methods for qualitative and quantitative analysis of foulants. Based on this analysis, antifouling strategies would be developed, to manage dynamic effects, such as sudden increases in hydraulic and organic loading.
  • PURATREAT was supported in support of international co-operation for Mediterranean Partner Countries with a budget of £766,000M and coordinated by the Technologie-Transfer-Zentrum in Bremerhaven, Germany. The objective was to evaluate MBR technology as a specific tool to alleviate the water stress in the Mediterranean and North African Region, adapting cost and performance to allow reuse and improve the infrastructure.

One of the results of the studies was a market survey of the European MBR industry, contacting 33 suppliers or retailers of MBR filtration systems and/or MBR plant constructors, recording more than 400 references. Of these, about 300 were industrial applications (> 20m3/d), and about 100 municipal WwTPs (> 500 PE) were also identified. On average, the capacity of industrial applications was an order of magnitude smaller than municipal applications (median flows of 180m3/d and 2,500m3/d respectively), leading to the municipal sector dominating 75% of the market volume. The trend showed that in the coming years, at least 70 new MBR plants are expected to be constructed annually, with about 50 industrial and 20 municipal applications.

The predominance of immersed MBR filtration systems in both sectors is undisputed, as during the period of 2003 to 2005 they represented 99% of the total installed membrane surface (Zenon-GE and Kubota, two non-European suppliers, representing 63% and 30% respectively).

Unexpectedly, Italy comes first for industrial applications with 20% of the installed plants. Germany, France, and the Netherlands follow with 40-60 MBR units in operation.

In the municipal market, the UK had the early lead with 40 % of the applications in 2005, and appearing to be the only country with more municipal than industrial MBR plants. The next countries for the municipal sector are Germany and Italy, with 10-20 plants, and Spain has caught up strongly in the last few years, more than doubling the number of installations and surpassing France and the Netherlands with five to ten references each.

But as in many other fields, the Middle East and Asia are playing the game of “mine is bigger than yours” more aggressively.

  • In Dubai, the largest MBR plant with a capacity of 25,000m3/d was started up at the end of 2009 using hollow fibre membranes, with around 10% of the MBR effluent polished by a reverse osmosis (RO) system to generate potable quality water, with the rest being recycled for irrigation.
  • The Al Ansab MBR sewage treatment plant in Muscat, Oman, was successfully tested in autumn 2010 for an initial contract flow of 76,000m3/d. The plant uses flat sheet membranes with 304 Kubota EK400 doubledeck modules, or a total of 121,600 panels – more than ten times the number of panels

    installed in the UK’s largest MBR plant in Swanage. The final capacity of the plant is projected to be three times higher, and will treat an ultimate equivalent population of 900,000 people, or 220,000m3/d.
  • Early in 2010 another “largest” MBR plant was announced in Singapore, at the Jurong Water Reclamation Plant for PUB, Singapore’s national water agency. Hydranautics won the order from Singapore firm Hyflux for a microfiltration membrane manufactured by Mitsubishi Rayon with a dry weather capacity of 45,000m3/d and is scheduled to begin operation at the end of 2011. (See Consultant & Contractor File for more on Jurong.)

    Of course, ” you ain’t seen nothing yet”, if you have not been to China, where the boom of biggest is best is blooming bountifully.
  • Three months before the 2008 Beijing Olympic games, Siemens Water Technologies started up a wastewater reuse system at the city’s Beixiaohe WwTP, adding 60,000m³/d of capacity with 4,864 Memcor Memjet hollow fibre membranes with a total area of 180,000m².
  • Also for the Olympic Games, the WenYuHe Project was started up in October 2007 with an MBR system of 100,000m3/d to transfer water from the Wenyu River to the Chaobai River for landscape irrigation and use at the Shunyi Olympic Water Park for rowing and canoeing.

    The second phase of another 100,000m3/d is under construction by Origin Water of Beijing.
  • In September 2010, the Jing Xi WwTP in Guangzhou, for a capacity of 100,000m3/d was inaugurated, constructed in three levels with an underground depth of 20m, occupying just 1.6ha of land. The EPC contract was performed by United Envirotech of Singapore using MBR technology from Memstar, based on PVDF hollow fibre membranes.
  • The Qinghe WwTP in Beijing was further expanded by 20% at the end of 2006, adding GE Zenon MBR facilities for 80,000m³/d to supply the Olympic Village with reuse water.

    In June 2010, a contract was awarded to Purac China for an MBR upgrade with 19 drum screens with 1mm openings, which will allow the Qinghe plant to have an MBR capacity of 240,000m3/d, the largest MBR plant in the world.

    n That would leave the Brightwater MBR in King County, Washington State, trailing – it is now expected to be commissioned in September due to delays in construction. The initial average capacity is 136,000m³/d, with a peaking factor above 3, and the final average flow in 2040 is projected to be 205,000m³/d.

In the meantime, the Johns Creek Environmental Campus (JCEC) in Fulton County, GA, has the bragging rights for the biggest MBR in the US, opened in July 2010 for 57,000m3/d of reuse water for irrigation.

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