Tackling endocrine disrupting chemicals

Paul Boughton

Chemically-disrupted water streams are causing a substantial increase of 'intersex' fish. Nicola Martin reports on how peristaltic technology is being used to address the problem of water pollution through more effective treatment techniques.

It's the story that has become an international curiosity: male fish swimming in Europe's rivers have begun spontaneously developing female characteristics.

Research dating back more than 15 years has revealed that the underlying cause of this 'intersex' fish phenomenon lies in improved water quality allowing fish to colonise rivers which were previously fishless. This has meant that fish are surviving in the upper reaches of urban river systems and are more exposed to treated sewage effluent.

It is believed that endocrine disrupting chemicals (EDCs) such as natural and synthetic hormones in the wastewater effluent are causing the intersex effect in male fish such as the appearance of oocytes (egg cells) in their testes. It is a problem that has been under the spotlight of the European Chemical Industry Council for more than a decade now.

EDCs are typically found in wastewater at concentrations of less than one part per ten billion and are a minute fraction of all the organic material present. This means that the processes traditionally used to treat contaminants found in wastewater are insufficient for their complete removal. For example, trickling filters are likely to remove less EDCs than a nitrifying activated sludge plant, and processes such as ozone and granular activated carbon treatment are likely to remove even more. Further research is imperative.

An initiative has been launched in the UK, where the Environment Agency, in collaboration with the government and the water industry, has co-ordinated a £40million national programme to examine EDCs and assess the effectiveness, costs and benefits of their removal in existing or enhanced sewage treatment. The programme is gathering data from 13 different types of sewage treatment works across England and Wales. This includes a notable project at Ilkeston sewage treatment works near Derby in the English midlands.

Undertaken by Severn Trent Water, the Ilkeston project requires the company to carry out a side-by-side evaluation of three different advanced treatments for removal. In addition, the company is carrying out fish tests using native roach to determine the effects of different waters on them (Fig.1).

The experiments include the comparison of river water, treated sewage effluent and dilutions of treated sewage effluent in tap water. In order to make useable the tap water in the sample tanks, the chlorine in the water must be neutralised. For this purpose, Severn Trent specified the use of Watson-Marlow's 520SN/R2 peristaltic pumps for dosing of sodium thiosulphate, which dechlorinates the water (Fig.2). The 520 series of peristaltic pumps can be calibrated either by weight or volume, allowing for the precise dosing and metering that is necessary in the Ilkeston trial.

Severn Trent is also using SPX25 hose pumps that feed the river water and treated effluent to the tanks. The benefits of the hose pump for the river water are that the suction lift is good so that the pump can be situated safely inside the works perimeter fence with only the suction hose suspended in the river. The ability to handle solids also meant that only a simple weed screen was necessary to prevent blockages with weeds and other debris.

Because peristaltic pumps retain the chemical completely within the tube and have no valves that can leak or corrode, they can be used for the closely-controlled metering of problematic chemicals such as sodium thiosulphate during treatment processes.

One of the central challenges of the EDC research programme is how to maximise removal efficiency by modifying current treatment technologies, while also remaining cost-effective. Advanced water treatment technologies are often more expensive than conventional treatment. This is another way in which the increased use of peristaltic technology is aiding EDC removal, by improving cost-effectiveness.

Philip Bolton, water industry specialist at Watson-Marlow, comments: "The previous engineering solution for this kind of trial used gear pumps to achieve the flow rate and pressure required, but this involved a high level of maintenance, as well as a complicated pressure regulation system utilising bypass valves. By contrast, peristaltic pumps are simpler and more reliable. Decreased maintenance requirements of peristaltic pumps mean that not only are costs lower, but engineers' time is freed up to be spent elsewhere."

The Ilkeston trial should provide increased knowledge of EDCs and the best methods to keep them out of surface water systems.

Cefic and the LRI

Over the years, there has been growing awareness and concern about the potential impact of human activity and man-made substances on the environment and human health. According to Cefic, the chemical industry is conscious of the need to address societal concerns and take responsibility in understanding the long-term impacts of its products and processes.

The idea for LRI began in the USA in 1996, with the goal of responding to public and stakeholder concerns through scientific investigation. The focus is on gaps in industry's knowledge and understanding that are critical for risk assessment.

The broad aim is a validated infrastructure of scientific advice on which the entire industry and regulatory bodies will draw to respond more quickly and accurately to the public's questions.

LRI sponsors research to help address some of the priorities of the European public health strategy, including: improving risk assessment of chemicals and, more specifically, monitoring effects of chemicals on health; understanding the environmental factors in human health; establishing endocrine disruption references; co-ordinating research, data and activities at a European level.

LRI also addresses many of the environmental objectives of the EU, including: linking environmental factors to health effects; understanding and reducing chemical risks to environment; and improving animal testing in risk assessment.

Among more than a hundred ongoing LRI projects are four specifically focused on the environment and wildlife. Their titles are: Review of the relative contribution of industrial chemicals, compared to steroids, in causing the sexual disruption in wild fish populations; Endocrine disruption in the marine environment; Endocrine disruption in the aquatic environment - laboratory investigation of endocrine-active chemicals; Endocrine modulating effects in fish along the Elbe River and in reference areas; environmental effects on uterine tissues of Baltic seals with special emphasis on organochlorines and uterine leiomyomas; Development, validation and application of in-vitro and in-vivo test systems for non-oestrogenic endocrine disrupting chemicals in wildlife: and Further development and scientific evaluation of appropriate methods for identification and characterisation of toxic effects of hormonally active substances on reproduction in birds as part of multi-generation studies.

Nicola Martin is a writer at environmental communicatons specialist, IMS Consulting, Bristol, UK. www.imsplc.com