Effects of Minerals in Dairy Farm Water Supplies

New Zealand Journal of Agriculture, Volume 84, Issue 1, 15 January 1952, Page 47

Effects of Minerals in Dairy Farm Water Supplies

AN adequate supply of suitable water is essential for dairy farmers to succeed in producing good-quality milk and cream. Some of the difficulties which arise when a farm water supply contains undue amounts of : dissolved minerals are described in this article by S. G. Davidson, Farm Dairy Instructor, Department of Agriculture, Oamaru. RIVER or creek waters may contain a variety of contaminating substances, including solid matter in suspension, derived from the land through which they flow. Such waters usually contain only small amounts of dissolved minerals, so they are quite suitable for use in the milking shed and for cleaning of dairy equipment, except where the stream is subject to pollution from drainage of various kinds. If it is necessary, stream water can easily be filtered to remove impurities. Well and bore-hole waters, particularly if the bore is deep, are usually of high organic purity, owing to the filtering effect of their passage through the overlying strata, but they are often rich in mineral compounds derived from the same source. The hardness of such waters varies widely in different localities and supplies of water available from different sources may be regarded as dilute solutions of a number of chemical compounds, together with organic matter in suspension. ... . ' On many farms throughout New Zealand water drawn from springs, wells, or bore holes is the main source of supply to the milking shed. In many cases such supplies, particularly hard, corrosive, and iron-bearing waters, are unsatisfactory for use in cylinders of electric water heaters and give much trouble in the cleaning of dairy equipment. Damage to Electric Water Heater Where water which is hard owing to dissolved minerals is used its effect on the efficiency of the cylinder of the water heater will soon become noticeable. After the heater has been in use for a period the water, instead of being heated to the normal temperature range under thermostat control (196 degrees to 206 degrees F.), obviously is not becoming as hot as formerly, and as time goes on this lowering of temperature steadily becomes worse. The reason for this will be obvious if the heating element ,is removed and inspected, when it will be found to be covered by . hard mineral deposits which act as an insulating medium and impair the efficiency of the element. If the element were left long enough in the cylinder without attention, these deposits would build up and cause the element to burn out when they became thick enough to prevent the water having contact with it. By the same process the heating of the water would become progressively slower. For these reasons efficiency of electric water heaters is considerably reduced where hard water is used. Should water of an acid nature be used in the heater, corrosion of the joint where the tap is fitted to the heater may quickly occur and cause a leakage. A brownish encrustation may form owing to the corrosion of the iron pipes. The Milking Machine To clean the milking machine properly it is necessary to rinse it thoroughly -with cold water to remove all traces of milk, and whether or not the water is hard or otherwise unsatisfactory, there should be no restriction on the use of large quantities at this stage. The recommended procedure after a complete rinsing is to flush the machine with a solution of boiling water and caustic soda at the rate of 1 heaped teaspoon of caustic soda to 4 gallons of boiling water. If hard water is used, some curdling takes place when the caustic soda is added to the water. The cleansing effect will then be weakened, but this can be compensated for by using a suitable soda ash mixture containing a wetting agent to supplement the caustic, as described by G. M. Moir in the “New Zealand Journal of Agriculture” of February 1951. One teaspoonful of soda ash mixture should be added to the boiling water, and to get efficient results it is most important that the soda ash be dissolved before the caustic is added. The solution resulting from this mixture is used at the rate of 1 gallon to each set of teat-cups, followed by at least 1 gallon of clean boiling water to ensure that all traces

of the solution are removed. If this is done twice daily, it is usually sufficient to keep the milking machine in a bright,, sanitary condition, especially if the water used is reasonably soft. Where very hard water is used for cleaning there is early evidence of the inside surfaces of the metal parts of the milking machine and utensils becoming dull, owing to a deposit of a hard whitish precipitate derived from limestone or other minerals. If iron-bearing water is being used, the deposit will be seen as a reddish-brown film. When used . cold these waters do not usually leave any deposit, but when they are applied hot or boiling the deposit soon appears. The continued use of hard water causes a progressive accumulation of such deposits. At the same time these deposits build up on the heating element of the electric cylinder and prevent the water reaching a temperature high enough to clean and sterilise the milking machine and equipment thoroughly. Although a stronger solution of caustic soda is used, or a soda mixture is added to the solution, the water will not be hot enough to remove the fat from metal and rubber parts. When the rough surface develops inside the metal pipes of the machine bacteria grow in large numbers and soon provide a serious contamination. As the water is not hot enough to remove the fat from rubberware, this will perish more rapidly owing to the penetration of such fat. The contamination from deposits, and from bacteria which are harboured in these deposits and which have developed because the water temperature is not high enough, is serious and good-quality milk and cream cannot be produced under such conditions. The separator and buckets will also be encrusted, although perhaps not as much as the metal of the milking machine. Hard water is quite satisfactory for cleaning the floors, walls, and yards of the dairy premises, but in the case of iron-bearing water the concrete will be stained a reddish brown and become unsightly. A convenient and satisfactory method of removing mineral stone is that recommended for the removal of milkstone in Department of Agriculture Bulletin No. 347, “Farm Dairy Instruction”.,

Softening Hard Water

There are various methods of softening hard water, and farmers are advised to have an analysis taken, as this is essential before any softening process is undertaken. Analysis will ascertain what organic or mineral compounds are contained in the water, and the degree of hardness. Where acid is present the water can be treated by adding certain mild alkaline substances, and by filtration through a suitable medium, as by the Permutit process, such waters can be softened. The hardness of the water governs the softener required to ensure a satisfactory supply. The Permutit sand can be regenerated by treatment with a strong salt solution. Filtering methods for softening water, although effective, may be unsuitable in farm dairy premises, and it is suggested that a water tank of at least 600 gallons capacity be installed at the milking shed for holding rain-water. This should be sufficient to ensure a good supply of soft water, but if this supply is to be drawn upon for cooling milk or . cream, the holding tank should be installed underground.

If a . rain-water tank is installed at the dairy premises, a supply of soft water for use in the electric heater and for cleaning the equipment is assured, and the difficulties arising from the use of hard water are overcome. The equipment will not perish and corrode as rapidly and the necessary removal of mineral stone from the metal parts will be less frequent. Unless soft water is used in the electric cylinder and for cleaning the dairy equipment, corrosion and encrustation will constantly occur, and in turn dairy produce will be lowered in quality by coming into contact with the encrusted deposits and by ineffective cleaning of equipment because the water used in flushing is not boiling.

Summary of Corrective Methods

Suggested methods of overcoming the difficulties arising from the use of hard water containing large quantities of dissolved minerals are as follows: —

1. Wherever possible a tank should be provided for holding rain-water exclusively for use in the electric water heater and for flushing and cleaning the milking machine and dairy utensils.

2. A soda ash mixture may be used with a caustic soda solution as already described. A solution of this kind is particularly useful in washing the dairy utensils, apart from the flushing of the milking machine. Though this cleaning alternative will improve the condition of the dairy equipment, it obviously will not prevent the formation of mineral deposits on the element of the electric water cylinder, nor prevent a reduction in its efficiency. Soft water is essential for this purpose.

As stated, there are various methods of softening hard water, and where necessary the advice of Farm Dairy Instructors should be sought. The installation of suitable water-softening equipment will involve some expense, and the farmer must be prepared to give the equipment regular attention to get satisfactory results.