Chemically-disrupted water streams are causing a substantial increase of ‘intersex’ fish. Now Watson-Marlow peristaltic technology is addressing the problem of water pollution through more effective treatment techniques.
It has become a national curiosity: male fish swimming in our rivers have begun spontaneously developing female characteristics. Research dating back more than fifteen years has revealed that the underlying cause of this ‘intersex’ fish phenomenon lies in our 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 the testes of male fish.
EDCs are typically found in waste water 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 waste water are insufficient for completely removing EDCs.
Undertaken by Severn Trent Water, the project requires the company to carry out a side-by-side evaluation of three different advanced treatments for removal. In addition they are carrying out some fish tests using native roach to determine the effects of different waters on the fish. 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 a Watson-Marlow’s 520SN/R2 peristaltic pump for dosing of sodium thiosulphate, which dechlorinates the water.
Severn Trent is also using Bredel 25 hose pumps which 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 etc.