Our ERE students gathered on Saturday April 21, 2012 to obtain hands-on training in appropriate technology for drinking water supply – this time building a sand filter and photovoltaic power supply for their previously built ram pump and UV purifier. The workshop was led by Mr. Doug Hollinger, founder of the Global Youth Service Team, which focuses on supplying water for Burmese refugee camps, and a physics teacher at Pavilion Central School in NYS.

Water supply system in Burmese refugee camp in Thailand. Image courtesy GYST

In the previous workshop, students constructed two hydraulic ram pumps and two UV water purifiers. The ram pumps use built up pressure in a PVC chamber to send water from low elevations to high elevations. The UV water purifiers use the sterilizing capacity of the ultra-violet light’s wavelength to stop the bacteria from reproducing in the water. For the UV to work, all sediment needs to be filtered from the water so the light can penetrate into the water column. To power the UV filter a solar array was needed.

SUNY ESF ERE students with Doug Hollinger and Ross Jacobs, two instructors.

The biosand filter can be sized to serve a family or community and is intended as a point of use system. To begin, a 3” PVC tube was cut to 105 cm. The purpose of a consistent height of the PVC tube is to maintain the flow rate of water through the filter. The proportion of substrate in the filter is essential to maintaining around 0.4 L of water per minute. At this speed, the removal of suspended solids and pathogens is maximized. The gravel and sand, which are the main components of the filter, were washed before they were added to the filter. A diffuser plate sits seven inches above the sand to allow water to trickle into the filter and to allow a biological layer to develop in the standing water. The biological layer consumes the bad bacteria in the unfiltered water and begins the filtering process.

Sand filter components - washed sand at top of image, PVC column at bottom.

The photovoltaic (solar array) panels are connected in parallel to ensure continuous voltage throughout the system and are connected to a main circuit box. The panels are adjusted to intercept the maximum density of sunlight photons, angled so their face is perpendicular to the solar angle. The photons from the sunlight bombard the silicon plates in the panel and break the electron away from the negative plate. The positive silicon plate then attracts the electron and this process, which is repeated many times in a solar panel, provides the needed electricity. The photovoltaic system is coupled with charge controller to regulate the battery charge.

Solar arrays used in PV system to power UV purifier in water supply delivery.

In culmination, the students were eager to see how the four technologies that were built during the workshops could work together. From a water source, the hydraulic ram pump moves the water uphill to the point of use. There the water is passed through the biosand filter to remove pathogens and suspended solids. To further the disinfection process and to prevent disease, the water is passed through the UV water filter, in which the bulb is powered by the solar panels. The bulb is powered by batteries and the batteries are charged by a photovoltaic system so it can work day and night. The entire system proves that water quality can be improved in developing countries by implementing appropriate technologies.

Team of ERE students with instructors Doug and Ross and their community water supply technologies.

Many thanks to Mr. Doug Hollinger for coming back to Syracuse to share his knowledge, SUNY-ESF ERE alumni for providing the materials, and Dr. Ted Endreny for making the workshops a success. With the knowledge and experience gained, life saving appropriate technology can be brought to developing countries.