The new treatment plant at Saint's Hill has been operating since May 1992 and biologically treats ground‐water to remove iron, ammonium/ammonia and manganese. The paper describes the project, the processes involved, the significance of pilot‐plant studies, the different stages of commissioning and plant efficiency. This method of treatment, although new to the UK, is well‐established in France, and reference to existing plants using the processes is made for purposes of indicating the range of applicability of biological treatment processes. Specific conditions are required for biological processes. Not all raw waters can be economically treated to produce an environment which is appropriate for bacterial activity. Conditions for biological iron and manganese removal are different. The paper illustrates the importance of pilot studies to establish the feasibility of biological processes and to determine the design parameters for industrial‐scale works.

Table 2. Standard methods in use by the DRI Water Analysis Laboratory (Rcno, NV). Parameter Standard Method i i pH EPA-600/4-79-020, Method 150.1 Specific Conductance EPA-600/4-79-020, Method 120.1 Alkalinity USGS, Method 1-2030-85 Chloride EPA-600/4-79-020, Method 325.1 Sulfate EPA-600/4-84-O17, Method 300.0 Sodium EPA-600/4-79-020, Method 273.1 Potassium EPA-600/4-79-020, Method 258.1 Calcium EPA-600/4-79-020, Method 215.1 Magnesium EPA-600/4-79-020, Method 242.1 Silica USGS, Method 1-2700-85 Bromide EPA-600/4-84-O 17, Method 300.0 Nitrate and Nitrite EPA-600/4-79-020, Method 353.2 I I Water Content Analysis Water content on weight and volume basis was determined for Pilot Well and Science Trench boreholes. Data are presented in Appendix A. Water content profiles from the three Pilot WeUsillustrate that water content values are very low and do not change much through the unsaturated zone. There is only a slight increase in water content with depth and a very significant increase, as would be expected, near the water table (Figures 3 and 4). Ploaed vertical profiles from the Science Trench boreholes indicate that water content values are also very low and constant throughout the approximately 120 ft of alluvium penetrated. The only noticeable trend is a slight increase in water content with depth (Figures 5 and 6). Soil Bulk Density Bulk density is an input parameter for numerical simulations of fluid, heat, and solid transport. Bulk density data arepresented in Appendix A. Plots of bulk density vs. depth forthe Science Trench boreholes (Figure 7) show no consistent trend within or between boreholes except for a slight increase in bulk density with depth in the upper 20 ft of each borehole. This increase may be a sampling artifact. No consistent trend in bulk density with depth was identified in the Pilot Well boreholes (Figure 8). Soil Water Potential Depth profiles of water potential data from the Pilot WeUs and the Science Trench bo,'eholes are summarized in Appendix A. Physical and hydrologic data for Ue5PW-2, Ue5PW-2A, Ue5PW-2B and Ue5PW-2C. Depth Total Gfrav. Bulk Vol. Water Sample Borehole Interval Potential Water Density Water Potential ID No. fit) CX-2 (KPa) Content (gr/cm3) Content Filter P. (IGUa)

This paper describes an investigation using biological‐iron removal for the elimination of arsenic (III). Groundwater was spiked with sodium arsenite and filtered through a pilot unit. As the water filtered through the sand, arsenic was retained on the iron oxides which were continuously produced by the bacteriological activity. Under specific aeration and pH conditions, both arsenic and iron were eliminated. This process can be used for the design of a full‐scale biological treatment plant.

No abstract

The ozonation of water is widely used within the drinking‐water industry. The improvement of the performance of the Barcombe water‐treatment works is envisaged. An ozonation stage and granular activated carbon filtration are being considered as an addition to the existing plant. As part of the investigation work, the influence of ozone on bromate formation was studied using a 3 m3/h pilot plant. The bromate production was found to depend upon (a) the applied ozone dose, (b) the contact period, and (c) the pH. Using ozone in an appropriate way will be of benefit to the treatment process as well as meeting the new World Health Organization health guidelines for drinking water.