By Robert M. Halcrow,
J. E. Siebel Sons' Co., Inc. Chicago, IL
Published in October 1963

It can be fairly stated that a relatively large proportion of industrial water users fail to give proper attention to the quality of their water supply. This neglect may have been justified in the past when we could take our water supply for granted and felt secure in the assumption that it would always be adequate. This attitude was further fortified by the efficient water distribution systems that exist in most areas and by the universally practiced chemical treatment of the water to render it safe for drinking purposes.

As ground water supplies shrink, however, more and more cities and towns are turning to lakes, streams, or reservoirs to fulfill their water needs (1). This change from ground to surface sources of supply has created new problems for those engaged in the procurement and treatment of water for domestic, industrial, and other uses.

Ground waters are essentially free of organisms which may cause nuisance problems, whereas all surface waters contain many organisms and other contaminants which may complicate the provision of a potable water and, in particular, a suitable water for the production of beer. I should emphasize at this point that a water that is safe for drinking purposes is not necessarily suitable for beer processing.

It is surprising to note the number of people partially or totally immune to the chlorophenol taste in water or the so-called "medicinal" taste occasionally occurring in some beers.

1. Bacteria

   The "coliform" group of bacteria found in all surface water supplies, and sometimes in ground supplies, is probably the most significant from the brewer's viewpoint. While there is some difference of opinion regarding the presence of these organisms in potable waters, they do present a potential threat when found in water used in the brewery.

   Figure 1 shows a profuse growth of Aerobacteraerogenes growing in hopped wort. These organisms came from a brewery water supply. They are often referred to as "termobacteria" or plain "wort bacteria" and are generally the sole cause of biologically unstable wort. Fortunately, these bacteria do not develop in beer with a pH below 4.7 and, for that reason, are not likely to be found in the collected yeast crop.

   The mild, lightly hopped beers produced today require every pre caution by the brewer to guard against the entry of these bacteria into the wort. Water in the brewery should be periodically tested for the "coli-aerogenes" group of bacteria. It should be added that the typical off flavor in beer resulting from these wort bacteria is a "celery" taste and odor. At times, the off-flavor appears to be "earthy" or "smoky" and in milder cases, a fairly pronounced after-bitter might be the only taste sensation noted. Helm (3) mentions a reported off-taste found in thin beer during the war years described as "phenol-like". Gas- and acid-forming bacteria were detected in the wort from which these beers were made. After considerable effort, Helm succeeded in duplicating these findings, and a strong phenol-like off-taste and odor were produced as a result of infecting wort with an indol-negative type of E. coli. It was also found that a fermentation with yeast was a necessary condition for the development of this abnormal flavor.

   Practical observations show that prompt pitching of the wort with a good yeast which starts to ferment vigorously at an early stage does reduce the risk of developed off-flavors in the finished beer; however, this would prove ineffective should the wort be badly infected.

   The obvious question that will arise is: How do these coliform organisms escape destruction in chlorinated water systems? There are several factors that can account for this seemingly strange situation. Many municipal water plants use chloroamine treatment to prevent the obnoxious development of chlorophenols, and because of its slower reacting rate with organic materials, the residual chlorine is carried to a greater distance through water mains. Organic matter in the mains and in the water can provide protection to these organisms against chlorine; dead ends and seepage can add to the problem. The effectiveness of chlorine-releasing compounds and, in particular chloroamines, depends on the pH of the water and its temperature. Some authorities claim that it is unsafe to use choloramines in water having a pH above 8.5. When water is treated with chlorine, some of the bacteria are killed in a short time; the percentage killed depends on the excess chlorine over that required to react with bacteria and organic matter; the remaining bacteria are killed at a much slower rate.

   Not too infrequently, the development of the wort spoilage bacteria is unintentionally aided within the brewery. Such an instance occurred (4) when the decay of algae in sand and gravel filters provided a concentration of foodstuffs on the upper layers of the filters which led to a profuse development of coliform organisms. The low absorbing capacity (low frictional resistance) of the sand was such that the bacterial count of the effluent water was much higher than of the raw water. When sufficient particles collect on the surface of a filter (often referred to as a ripe filter), a mat or layer of suspended matter is formed which, in itself, acts as a type of filtering material. This action probably accounts for the reason why so many bacteria are held back on the upper layers of a sand and gravel filter. In a newly filled filter, where the deep layers do not hinder the passage of the bacteria grown in the upper layers, we again can run into a situation where the bacterial count of the effluent may be much higher than in the raw water.

   Activated carbon water purifiers can become a serious source of biological infection. I will return to this subject later. Suffice it to say, that bacterial growth is often stimulated in water passing through activated car bon. This effect is increased even further by the removal of residual chlorine by the carbon.

   Bacteria and organic matter in general can have a detrimental effect on water demineralizing units (5). Zeolite beds in themselves cannot support growth of bacteria. The organic matter that is filtered out by the zeolite, however, provides a source of food for reproduction of bacteria. Often pH, temperature, and other environmental conditions in the demineralizer are ideal for stimulating growth. Water with a low bacterial count can become heavily contaminated in passing through a badly fouled softener.

   A peculiar case worth mentioning took place in a city bordering the banks of the Ohio River. The filtered water passing through a battery of zeolite softeners showed a consider able growth of bacteria after two weeks' use of these units, and the treated effluent water showed increasing bacterial and coli counts, notwithstanding the fact that chlorine had been applied to the water before filtration. The interesting observation in this instance was the increase in numbers of A. aerogenes compared with E. coli, as was shown by cultivation on Endo plates. It would appear that the aerogenes bacteria are either more tolerant to chlorine or conditions in the filter favored their development.

   Slime-producing bacteria are quite adherent and cannot always be re moved by the action of regeneration and backwashing. The growths of slime and bacteria can impart objectionable odors and tastes to the water. Even when the odors and tastes are not objectionable, the slime can cover a significant portion of the zeolite so that regeneration is partially ineffective.

   At times, the picture becomes even more complicated should organic compounds of high molecular weight be present, principally the humic acids produced by decaying vegetable matter. Besides limiting the exchange capacity of the resins, these acids gradually diffuse into the resin gel and become tightly bound (6). Particularly in the case of anion-exchange resins, these larger molecular weight acids appear to be tightly bound or diffuse too slowly to be efficiently removed during the regular regeneration period, although limited success has been achieved using a warm five per cent sodium chloride brine. It is clear from these observations that the zeolite treatment of water calls for the efficient removal of organic matter from the water.

   Of interest to the brewer is a group of organisms commonly referred to as iron bacteria or Crenothrix. They form reddish-brown semi-submerged growths in stagnant surface water. Their characteristic color is due to their ability to abstract iron from their environment which becomes attached to the surface of their cells, either in the form of a slimy sheath or in their protoplasm. Not all species require iron to live; but when organic or inorganic salts of iron are present, an accumulation of ferric hydroxide is formed. Some species will attack only organic iron compounds. They particularly like waters of low pH, high CO2 content, and extreme hardness (particularly sulfate hardness).

   

   Some brewers who have switched from treated surface waters to other water sources for auxiliary purposes, such as in their pasteurizers, condensers, and cooling systems, are often plagued with the development of these troublesome organisms. In creased cost of water treatment chemicals, corrosion problems, reduced heat exchange, reduced flow rates, often accompanied by release of foul odors, are some of the penalties they might pay for using such waters. The coil-shaped organisms in Figure 2 be long to a species of Crenothrix. They are generally difficult to photograph because of the great masses of slime they produce which often hide them completely.

2. Algae

A nationwide survey published in 1958 (7) indicated that algae were considered by waterworks officials to be the most frequent causes of odors and flavors in water supplies, with decaying vegetation second in importance. For this reason, it will prove desirable to briefly discuss these organisms and, in particular, their influence on water supplies. We know very little about the potent odoriferous compounds which some species are capable of releasing in water. It is known that some of these compounds are not effectively removed by activated carbon.

Algae are common and normal in habitants of surface waters and are encountered in every water supply that is exposed to sunlight. While a few of the algae are found in soil and on surfaces exposed to air the great majority of them are truly aquatic and grow submerged in the waters of ponds, lakes, reservoirs, streams, and oceans. Many species have come to be recognized as important in water sup plies in many ways, such as by their capacity for modifying pH, alkalinity, color, turbidity, and lately the radio activity of water (2). Some are undoubtedly the most troublesome of the various types of nuisance organisms, but others can actually be put to good use in improving a water sup ply. For example, if it were not for the presence of algae, many of our waters would remain polluted. Algae provide much of the necessary oxygen to water which permits aerobic bacterial decomposition of organic matter. They allow many trickling filters in treatment plants to remain aerobic.

However, their presence and the presence of their by-products in brewery water can result in undesirable odors and tastes, clogging of filters and other equipment, as well as providing nutrient for bacteria. Corrosive activity of water is often increased as a result of algal growth. This can have far-reaching effects on the pipes in distribution systems.

Slime accumulations in the unlighted portions of distribution systems may be due to bacteria, carry over of coagulant, or to other organisms, but rarely to algae. In lighted areas blue-green algae, as a whole, are the most notorious slime producers.

Deep pits can be formed on the metal walls of exposed tanks as a result of the depolarizing action of the oxygen produced by algae. Algae in contact with submerged cement blocks have caused the complete disintegration of the concrete.

Often a considerable proportion of the decaying vegetation in water is composed of dead algal cells. The decay or decomposition is brought about by fungi and bacteria, including the actinomycetes. The latter are unicellular, filamentous organisms which are frequently looked upon as a separate group occupying a position between the fungi and the bacteria, although they are classified among the bacteria. As a matter of interest, odors that are produced through the activities of the fungi and bacteria may be either from intermediate products formed during decomposition or from special substances that are synthesized within the cells of the micro organisms. The latter appears to be true in the case of actinomycetes.

Algae of importance to water sup plies may be classified into four general groups; the blue-green algae, the green algae, the diatoms, and the pigmented flagellates.

Each year, a seasonal cycle is evident in the algal population of lakes and reservoirs. Diatoms generally in crease in number in late winter, often with two or three growth periods occurring during the spring months. In early summer, the green algae begin to flourish, followed in the late summer or early autumn by increased growth of blue-greens. Then there will follow a ]ate autumn maximum of diatoms. Throughout most of the winter, the diatoms and certain other algae may remain in the water, but with little or no increase in numbers, until conditions, in the late winter, stimulate the organisms to begin the cycle all over again.

Seasonal changes in thermoclines in relatively deep bodies of water can bring large quantities of algae to the surface, these conditions should not be confused with growth patterns.

A few algae are well known for the production of specific, distinctive odors and tastes while a large number of others are associated with odors and tastes that vary in type according to local conditions.

There are four types of odors usually associated with waters containing algae.

1. There is the "aromatic" odor which is sometimes described more specifically as that resembling a particular flower or vegetable. Common examples of these are geranium, nasturtium, violet, muskmelon, and cu cumber. In some cases, it is described as an attractive spicy odor but, in others, it may be very objectionable, for example, a skunky or garlicky odor. Relatively small numbers of diatoms and pigmented flagellates in water can produce some of these de scribed odors.

2. Then there is the "fishy" odor which is often produced by the same algae that are responsible for the aromatic odors, except that they are in larger numbers in the water. More specific terms that are often used to J describe the fishy odors are clam shell, cod-liver oil, seaweed, Irish moss, rockweed, and salt marsh. The difference between these odor impressions is not too significant as far as the group of algae responsible for them is concerned.

3. Next we have a type of odor that is somewhat aromatic which is best described as "grassy". It is the most common odor produced by green algae and is more apparent when the organisms are present in large numbers. It may also be due to certain blue-green algae and occasionally diatoms and pigmented flagellates.

4. The final type of odor is that which is often described as "musty" or "earthy". The latter is often associated with actinomycetes and with a few algae. It can vary from mild to decidedly pungent. The common musty odor in water is in most cases caused by blue-green algae and a few other forms. Odors in this group have also been described by such terms as "potato bin" and "moldy". Some waters have been reported as having weedy, swampy, peaty, straw-like and woody odors. These are possibly modifications or combinations of the grassy and musty odors.

The "septic", "pig-pen" or "putrefactive" odor of some waters is frequently linked to the presence of large accumulations of blue-green algae and occasionally some species of green algae. As these descriptive terms suggest, it is produced as a result of the decomposition of masses of algae, particularly where lack of sufficient oxygen permits the formation of odoriferous intermediate products from the algal proteins.

Chlorophenolic, iodoform, or medicinal odors and tastes may be produced by the action of chlorine on the products of certain algae.

The accompanying illustrations show some of the algae that are known to be offenders in water supplies. It will be noted that the majority of algae that are illustrated are members of the diatom group. There is a reason for this; most of the pictures were taken in the winter time from samples of mid-western waters, i.e., at a time of year when the diatom group of algae is predominant. Be cause of the problem of identification, only the generic names of the a alge will be used.

Figure 3 shows a dark field picture of a Synedra, a member of the diatom group. Note the pencil-like shape. In moderate amounts, it produces a grassy odor; in large numbers, it imparts a musty odor to water and a slick or oily sensation to the tongue. As their shape might indicate, these organisms can clog sand filters and have also been known to work their way through rapid sand filters. Be cause of their light density, they can interfere with coagulation in water treatment plants. Through their metabolic functions, they are capable of naturally softening water and can be rather persistent in some distributing systems. They can form loose visible aggregates called "blooms" in water systems and are sometimes associated with industrial wastes.

Another member of the diatom group, called Melosira, is shown in Figure 4. The geranium-like odor of some waters can come from this diatom when it is present in moderate amounts. When there is an abundance of these algae in water, a fairly pronounced musty odor can be noted; and similar to Synedra, they can impart a slick or oily sensation to the tongue when the water is drunk. They, too, can create considerable nuisance by clogging sand filters.

While Figure 5 does contain considerable debris, some needle-like fragments are distinguishable. They represent still another member of the diatom group, called Asterionella. In original form, these needles are joined together at one end in the form of a star. They can become serious of fenders in clogging sand filters, as their star shape readily disintegrates on contact with the sand or other solid objects. In moderate amounts, they produce a geranium-spicy odor, which can change to an obnoxious fishy odor should they become more abundant. They are quite readily destroyed in surface waters by copper sulfate; but should they be allowed to develop, they can adversely affect coagulation and can become rather persistent in distributing systems.

The organisms shown in Figure 6 belong to the green algae group known as Chlorella. They are notorious slime producers, often causing filtering difficulties, and are rather resistant to chlorine as well as copper sulfate treatment. They grow most profusely in surface water temperatures of between 85 and 95 degrees F., and show up in blooms giving a green cast to the water. Certain species of this group are often associated with polluted waters. In disposal plants, they are often used as an index regarding the progress in oxidation of sewage stabilization ponds. If the effluent count is principally chlorella, the pond is assumed to be working at or over its capacity. If the count shows a predominantly mixed flora, the pond can usually handle a heavier load.

The organism Anacystis shown in Figure 7 belongs to the blue-green algae group. It is quite readily destroyed by copper sulfate treatment; but if allowed to develop to moderate levels, a "grassy" odor in the water is often produced. In large numbers sufficient to form blooms, they some times produce a "septic" odor and the water will take on a rather sweet taste. The foul odor undoubtedly develops from products of decomposition as the algae begin to die off in large numbers. Like chlorella, some anacystis species are heavy slime producers (note the gelatinous matrix around each cell) and can clog sand filters. They can give a blue-green cast to water. A few species are associated with polluted waters, and some are known to attack concrete. In the absence of sufficient chlorine, some species are able to grow without the presence of light and can form "pipe moss" on the inner surfaces of water lines.

Figure 8 shows a colony of pigmented flagellates, called Gonium; some have classified it under the green algae group. Unfortunately, this is a black and white photograph and therefore fails to show the green colored chromatophore within the protoplasm of each cell. A gelatinous matrix, not very visible, surrounds and holds the cells together. In this case, the cells are encased and held in a flat plane; there are actually anterior flagella protruding from each cell which provide the motile movement for the organism.

This is quite a common alga in most surface waters; should it develop in large numbers, a fishy odor can occur.

A detailed view of the green alga Hydrodictyon is shown in Figure 9. Because of its open structure, it is commonly referred to as the "water net" and in some water supplies it can interfere with the flow rate through sand filters. If conditions are right, the organism can form dense mats or blooms on the surface of water. When extensive areas of these begin to die off, they can often produce a "septic" or "putrefactive" odor in the water. These blooms can prevent proper re aeration of some waters by excluding sunlight necessary for photosynthesis in the lower areas and thereby preventing release of oxygen into the water, or by depleting the oxygen through decay or respiration within the bloom. This condition can adversely affect the biological oxidation of organic contaminants in the water and can kill off beneficial aquatic plants and animals. Fortunately, hydrodictyon is very susceptible to the toxic effects of copper sulfate. If the methyl orange alkalinity of the water is less than 50 ppm, the effective rate of copper sulfate to use is 0.9 pounds per acre-foot; if greater than 50 ppm, five to six pounds are used. At higher alkalinities, copper sulfate will quickly precipitate as copper carbonate and more slowly as copper hydroxide; in such instances, it is considered to be effective as an algicide for a short time only following its application.

The species of Cladophora, a filamentous green alga shown in Figure 10, is considered to be one of the most abundant algae in running streams throughout the world. Al though usually associated with clean water, when large accumulations of this alga begin to die and decay, a foul "septic" odor is generated. This may happen as the depth of water in the stream recedes to a low level.

Finally, amongst the group of algae that we were able to photo graph, we found one species of Cymatopleura, which is reported to be one of the largest of the fresh water diatoms (Figure 11). It is a fairly uncommon alga and, for that reason, not much is known about it.

These then are some of the algae among a great many others not mentioned that can interfere with the quality of water supplies. For those who might be interested, there is available an excellent publication titled "Algae in Water Supplies" which is well illustrated and gives a wealth of information covering these organisms in water. It can be obtained through the Superintendent of Documents, Washington, D.C.

In that paper, mention is made of the wild yeast Pichia which is found in some water supplies. It is quite tolerant to anaerobic conditions, developing quite well in unpasteurized finished beer. It can also spoil wort and grow readily in fermenting beer. These findings have been substantiated by others. During those studies, there was also isolated from a brewery water a yeast-mold which was identified as Geotrichum Figure 12. While it seemingly produced no adverse effect in hopped wort, it did produce a distinct musty odor and taste in beer. Recently, we encountered a sample of water from a carbon purifier which, on addition to sterile hopped wort, yielded a pronounced musty odor and taste; on plating, we found a species of Penicillium mold.

Before touching on some of the points regarding purification of water for the brewery, mention should be made of the increasing problem created by industrial and domestic wastes

Biological oxidation is found to be the principal cause for destruction of phenols and cresols in surface waters. Under favorable conditions, phenol destruction is complete in a relatively short period. At least six factors affect the metabolic rates of organisms destroying the phenolic materials. These are: temperature, metabolic lag (similar to the lag phase in brewery fermentations), the nature of the initial microbial population of the water, the concentration of the phenolic compound, the specific compound involved, and the presence of nutrients such as nitrogen and phosphorus to permit utilization of the phenolic material in microbial metabolism. To give some ideas to the persistence of phenol in a relatively pure water having a B.O.D. under 1 ppm, it took two weeks to effect a 50 per cent reduction at 40 degrees F and 20 days for its complete destruction. In a biologically enriched water having a B.O.D. over 3 ppm, it took only five days under the same conditions to complete a 50 per cent reduction in phenol, and less than eight days for its complete destruction. This example stresses the importance of biochemical oxidation in the self purification of streams. Chemical oxidation and vaporization appear to play a minor role in the removal of most organic chemicals from waters.

Ortho- and parachlorophenol appear to be particularly resistant to biological attack, and for that reason are very dangerous in a brewery water supply. It has been claimed that orthochlorophenol is about 200 times stronger in odor and taste than phenol. Recent tests conducted in our laboratory indicate that orthochlorophenol is even many times more potent in odor and taste than has been claimed.

Most of the principal anionic and nonionic synthetic detergents are susceptible in some degree to biochemical degradation with considerable variation in the rate of attack, the rate being influenced by small changes in their molecular structure. Tetrapropylene benzene sulfonate, one of the principal anionic deter gents in current use, is extremely resistant to oxidation and is of considerable concern to those dealing with sewage and water purification. The alkyl sulfates are the easiest of all synthetic detergents for bacteria to attack and use for food material.

Earlier in this discussion, reference was made to the use of activated car bon purifiers. The use of such equipment in a brewery should be for a specific reason, namely, the removal of odor and flavor, along with the absorption of some of the soluble sub stances from water. While activated carbon is one of the most efficient and economical materials for the final purification of water, it is not the panacea for all the ills that befall water. Unfortunately, some brewers have tried to expand the duties of purifying units by thinking of them as also being capable of filtering water. While it is true that there are some units available that combine sand and gravel and activated carbon, these are intended for waters of rather low initial turbidity, coupled with processes requiring rather limited quantities of water.

Waters coming into contact with carbon purifiers and other treating equipment, such as zeolite softeners, should have a turbidity of near zero to maintain them at their highest peak of efficiency. It should be remembered that the "soaking up" of impurities by carbon takes place entirely on the surfaces and within the pores. It is easy to see why only clear water should come into contact with activated carbon beds. The important point about this absorption re action is the intimate contact necessary between the carbon and the water. If this necessary and vital con tact is destroyed by the presence of suspended matter or other dirt that will cover up the surfaces and pores of the carbon, efficient odor and taste removal is impossible. Waters of in creasing turbidity are likely to be waters containing increased amounts of organic matter and organisms. Many of these organisms find the carbon bed an ideal area for reproduction, so that, in some cases, the organism count in the so-called "purified" water is higher than in the unpurified water. The carbon units should be frequently back-washed and periodically steam sterilized. Chemical sterilization has not proved effective.

To obtain a water suitable for car bon purification, a number of preliminary treatments may be necessary. These treatments may range all the way from simple sand and gravel filtration to a combination of settling, aeration, coagulation, filtration, pre- and post-chlorination, followed by carbon purification. There are available various types of industrial water filters that are either manual or automatic in operation. These filters are replacing many of the older traditional methods of removing suspended matter from water.

Results seem to indicate that each water supply presents a distinct problem in treatment, depending on the amount and nature of the suspended solids, bacterial content, and capacity of the treatment units in terms of volume of water to be handled.

When a brewer plans a water treatment and purification system for his brewery, local, state, and federal water authorities can in many ways provide help. The authorities in most areas keep informative records of water supplies, covering such items as chlorine levels, algae, organic, and bacterial counts, temperatures, alkalinity, pH fluctuations, and organoleptic properties. These records, which are kept over the years, often reveal changing trends in the nature of the water supply and often indicate when to expect maximum ad verse conditions in each yearly cycle. From these data, water engineers can then install the best treatment and purification equipment to suit the brewery's needs.