Some Frank admissions
Frank Rogalla, now of Aqualia, used to frequently fly on planes - meaning he really stuck his carbon boot into the planet. But, he pleads, he has done some great sustainability work to make up for it
Since London would be my professional base - because it has five airports and would bring me within easy reach of almost anywhere in the world - that same event made it difficult for me to get planes.
One year later, when my wife's employer offered her an irresistible post, my family moved to Madrid. That required an almost weekly commute by plane for me. Now, after having flown more than 120 flights a year in the past two years, and looking at the greenhouse gas simulator one time too many, I decided it was time for a change.
A typical flight from my office in London to my home in Madrid would not only take about five hours, everything included - planning, booking, check-in, security, waiting, flying, plus transportation to and from airport - it also generated 0.18 tonnes of CO2.
Assuming all 120 flights were of similar duration - although there were a few longer ones to the US or Asia - and adding up the total yearly flights, that would take about 600 hours, one third of my yearly working time. It would also generate up to 22 tonnes of CO2 a year, or twice the average total per capita footprint for the industrial nations, at about 11 tonnes a person a year. It is also more than ten times the objective of two tonnes of CO2 a person a year needed to combat climate change, halved from the present worldwide average yearly carbon footprint of four tonnes.
So, I finally found the courage to switch employer again and start working closer to home.
I now work for Aqualia, the water and wastewater management company of the FCC construction group.
When I first started working in Paris in 1986, the main emission we worried about was odour, and energy was only a minor point on the agenda. The EU directives on drinking water (1980) and wastewater (1991) dominated the objectives to develop more efficient treatment technology.
In the period 1986-2003, the price of crude oil was relatively stable around the post-Second World War average of $25 a barrel (adjusted for inflation to 2007). But in the five years since 2003, the oil price has multiplied by a factor of five, changing the whole pattern of priorities. It is now necessary to view wastewater as a potential resource for energy and nutrients as, in theory, municipal effluent contains almost ten times the energy necessary to treat it.
For seven years, at the research centre of Compagnie Generale des Eaux (now Veolia), I led the development of high-rate biofilm reactors, known as biological active filters (BAF).
By using a filter grain to both grow a biofilm and to capture solids, only one tank was needed for biological treatment. This was instead of the orthodox approach of reactor and settler - and the biomass could be concentrated about five times on the support material.
This technology drastically changed the perception and implementation of wastewater treatment, as the compactness of the BAF plants now made it possible to reduce the footprint considerably, and implement treatment in urban settings, by placing the reactors in covered buildings.
This proximity, in turn, can reduce the cost of the collection system, which typically is 70-80 % of a conventional infrastructure. Above all, it would favour reuse, where in turn the distribution system is the major cost item.
The Urban Wastewater Treatment Directive obligated many plants that were discharging into sensitive waterways, mostly inland rivers, to upgrade for nitrogen removal. This normally meant multiplying their reactor volume by a factor of three to five.
The main objective of my work was to develop a cost-effective method to upgrade those existing plants. The Paris Acheres plant was the largest in Europe, with a dry-weather capacity of around 2.5Mm3/d and a high population density restricting further expansion.
First, the BAF technology was implemented in suburbs surrounding Paris to reduce the load on the large centralised plant, with installations in the new towns of Cergy, in the west, and Lagny, in the east, of the capital. Next, Colombes was built for a capacity of 240Ml/d on the four-hectare site of a major pump station feeding Acheres. Finally, on 29 June 2007, the largest BAF plant so far, in Acheres, was inaugurated by the French minister of the environment. It had a capacity of 1.7Mm3/d, treated on 84 cells with 173m2 of surface each.
Once the first BAF plants were operating on a large scale in France, my main effort was to spread the good news, and develop demonstrations and references in neighbouring countries where the upgrading of wastewater treatment plants was a priority. The first three plants were implemented with the high-rate floating biofilter:
- Nyborg, Denmark, total nitrogen (TN) removal (<8mg TN/l) for 13,000m3/d
- Herford, Germany, total nitrogen removal (<15mg TN/l) for 33,000m3/d
- Manchester-Davyhulme, tertiary nitrification for 375,000m3/d
In France, there are more than 100 plants from various process providers, and in the UK there are now more than 90 facilities. Germany has about 50 plants. Even in the US, a few large plants have now been started up in the Great Lakes region - Windsor and Thunder Bay, Ontario; as well as upstate New York - Binghamton and Syracuse; or Baltimore; each with a capacity of about 300Ml/d.
In summer 1994, Compagnie Generale des Eaux (CGE) increased its shares in Air & Water Technologies (AWT), a US company covering a large range of environmental services, to 40%. With this higher influence, CGE appointed a new chairman and management team.
I was part of the contingent sent to Metcalf & Eddy, one of the AWT companies active in water and wastewater, to facilitate technology transfer.
I was based in their New York office.
Among many fascinating challenges in that work, one was the nutrient removal in the 14 water plants of New York City. Most of them are in landlocked urban locations, with a total capacity of 6.9Mm3/d. The largest plant is at Newtown Creek and treats about one sixth of the total flow.
The City of New York is being forced to reduce its nitrogen discharge into the waterways by 60% by 2017, and reduce eutrophication in the Long Island Sound. A comprehensive pilot programme has been conducted over the years to try to optimise the investment, initially estimated at about £350M, mostly integrating biofilm technologies and treatment of solids dewatering centrate, as well as stormwater controls.
Simultaneously, the City of New York faced new regulations from the 1989 Federal Safe Drinking Water Act's Surface Water Treatment Rule, making the filtration of surface-water-sourced public supplies mandatory. Most of the 6.1Mm3/d of water for the city's residents is supplied directly from natural systems of upstate New York's Catskill/Delaware watershed, located about 100 miles north of the city.
This is chlorinated, but not treated.
New York is also building the largest UV disinfection plant in the world, with a total capacity of up 8.4Mm3/d.
Construction started in January this year and completion is anticipated in 2012. Fifty-six reactors with a unitary capacity of 150 000m3/d are being designed specifically for that plant.
After only three years in New York, the calling came to get to know an even bigger city, São Paulo, Brazil. New York has a little more than eight million people in its five boroughs. In comparison, the city of São Paulo has more than 11 million people in its political boundaries. The city is challenged by the location on a mountain plateau, exposed to drought conditions in summertime and to flooding in the rainy season. Its main drinking water plant has a capacity of 2.7Mm3/d, the largest drinking water plant in South America.
In comparison, the peak freshwater demand is probably twice as high, and its wastewater treatment capacity - dating from 1977 - only accommodated 600Ml/d. The plan to expand the capacity was implemented, little by little, with international co-financing by the Interamerican Development Bank.
The first step, from 1992 to 1998, was the extension of the existing large water and wastewater treatment plants in Barueri by 33%. An additional three plants and related collection systems were built in order to increase the sewage collection rate from 70-80% and increase treatment by a factor of 2.5-62% of the collected wastewater.
The second phase of investment, reaching an overall figure of £75M, is currently under completion and is expected to increase the collection rate by another 5%. It should reach a treatment efficiency of 70%. Over the past ten years, the BOD in São Paolo's main river, the Tiete, almost halved from close to 40mg/l to about 20mg/l. Another £500M of investment is planned in the next decade to increase the collection rate to more than 90% and provide treatment to more than 80%.
While the treatment plants in metropolitan São Paulo have conventional primary and secondary treatment with anaerobic sludge digestion, many cities in Brazil have adopted anaerobic pre-treatment. This allows considerable savings in energy consumption and solids disposal. Anaerobic
pre-treatment has been built into plants with a capacity of more than100Ml/d in some of Brazil's larger cities, such as Curitiba in Parana State and Belo Horizonte in Minas Gerais. Theoretically, it is possible for these plants to produce enough energy to power the aerobic post-treatment and to become self sufficient, although none of them has yet implemented the conversion of biogas to electricity.
With four years of experience in various projects in South America, I had the priviledge to be invited to work for Black & Veatch by Dr James Barnard, and for the past seven years, participated in more innovative approaches, such as the Dublin wastewater treatment plant. Here, energy harvesting from biosolids is maximised by boosting the anaerobic digestion with thermal hydrolysis.
Enriched with the knowledge of anaerobic pre-treatment of municipal wastewaters in Brazil, we incorporated this technology with submerged aerobic filters for the city of Ajman in the United Arab Emirates. A plant for 50,000m3/d is now under start-up.
Hopefully my contributions to the sustainability of treatment technology will compensate for some of the excessive carbon footprint generated by my personal choices.