Questions and statements about sludge, food-cycles and agriculture
1. Isn't it a good idea that the plant nutrients in urine and feces be returned to farmland ?
Yes, certainly. Urine and feces are the concentrated nutrient remains of the food we have grown. Urine and feces are naturally very low in heavy metals and contain micronutrients from diverse food sources. Many soils lack these micronutrients because they have been "mined" and not returned as the result of poor agricultural practices. These micronutrients -- such as Selenium which we predominantly get through fish --are rarely present in chemical fertilizers. But the practice of mixing urine and feces with large amounts of municipal tapwater--(leaving aside for the moment the question of what it means to add them to municipal sewage)--adds unnaturally high amounts of heavy metals to sewage treatment sludge. This contamination of excreta with heavy metals is part of the reason why urine and feces should be kept separate from municipal sewage.
2. But if we use the sludge from sewage treatment, couldn't we eliminate the use of a large portion of the chemical fertilizers now in use?
It is true that chemical fertilizers in some instances have been destructive to the micronutrient and humus content in soils. But this sort of damage is remediable.Sewage sludge, on the other hand, is several orders of magnitude more destructive in the long run, and the damage it can cause is irreversible. Municipal sewage sludge typically contains only 1% of the three basic plant nutrients (phosphorous, nitrogen and potassium). The other 99% is a highly complex mixture of other substances which have been extracted from municipal sewage. Municipal sludge contains, for example, harmful heavy metals to a much greater degree than chemical fertilizers. (See table below).
3. Isn't the world's natural supply of phosphorous about to be used up if we don't use sludge?
No, this is a misunderstanding. Phosphorous is a basic element, which cannot be used up (as opposed to,for example, oil which is consumed as a material and altered to a lower energy form). But phosphorous can be misplaced or mixed with other elements that make it useless for all practical purposes. Through some systematic errors in agricultural practices (where, for example, most livestock and crop farms are separate), the phosphorous in manure, along with other nutrients and useful metals, only gets recycled back to farmland where there is livestock is raised. Around 80 % of the crops that are fertilized with manure goes back to feed livestock.Sustainable agricultural practice would require that this manure be earmarked for the crops destined to feed people. There is around 5 times more phosphorous in animal manure than in the human excreta. To more safely close the cycle in agriculture we must replace sludge fertilization with stabilized manure fertilizers derived from both animals and humans. The amount of phosphorous that leaches from the soils to the oceans (a large P-reserve) is small since phosphorous is trapped by most soils. (Se below).
4. Isn't the purpose of spreading sludge on the land the creation of a sustainable cycle between city and country?
Sludge can never be part of any sustainable cycle since it contains unsustainable and unpredictable levels of heavy metals and toxic substances/compounds. The metals present in non life-compatible concentrations and amounts in sludge accumulate in the soil until--sooner or later--they reach levels toxic to plants and animals including, of course, humans. This is an unresolvable system error stemming from the central collection and mixing of heterogeneous waste materials and water.
5. Can't the concentrations of toxic metals be eliminated by preventing the discharge of metals into the sewer system?
Even if urine and feces alone were mixed and transported by tap water, the resulting sludge would be high enough in metals to make its use as fertilizer inadvisable. Metals and toxic chemicals from industry (i.e., "point-source" contamination) can--and should--be reduced. Nevertheless, sewage sludge will, by reason of its unpredictability, remain too dangerous to risk using. Furthermore, the metals and chemicals now in commerce are bound to find their way into the sewers systems since sewers provide such convenient and cheap means of disposal. This only adds to the reason why sludge will forever be a high risk substance and therefore useless in a sustainable agriculture.
6. Are you saying that even in water treated for drinking there are enough metals to make municipal sludge unsustainable?
Yes, this is in fact the case. Every human excretes about 1-3 Kg urine and feces per day. But, if we are on a municipal water supply, we add to this small amount or excreta about 200 liters of tap water per day (bath, dish, flush and wash water etc). At the sewage treatment plant, this level of residential consumption is added to by municipal sources and the resulting dilution is equivalent to about 700 liters per connected person. [example from Ryaverket sewage treatment works in Göteborg, Sweden]. Even where the concentrations of metals in the tap water are very low, they will, to the extent that the sewage treatment operates properly and efficiently, be further concentrated in the sludge. Some of the metals come from the water treatment plant, others are added along the way as the water travels through the piping network where sloughing off from the various metals of which it is made cannot, in a large distribution and collection system, be avoided. (Se sid 9 och 10). In other words, by transporting the body secreted nutrients with 700 liters of water, we increase the metal content in those nutrients 700 times the metal-content in a liter of tap water -- now the amount is significant.
7. Since not all plants take up metals, and since some soils even require the addition of some metals, why do metals pose such a threat?
It is well known that the difference between the necessary and the toxic is very small in the case of plant uptake of metals. Metals that are taken up by plants are removed from the soil when the crop is harvested. But since most crops become animal feed, most of the nutrients and metals end up in animal manure [and other harvested "bi-products" -- like straw] This manure in turn is put back on the land, predominantly to make more animal feed.However, when the manure is not returned to the animal feed-producing soils, some metals ( e.g., copper and zinc) are at risk of being depleted and need to be added to those soils. But these same metals readily become toxic to plants and animals in concentrations just a very small amount greater than what the plants need for healthy growth. We know that sludge adds metals in higher than ambient amounts and that damage to crops and livestock does indeed occur. (Such damage goes either unreported, or if reported is routinely relegated to the category called "anecdotal." We know also that metal concentrations are on the increase in agricultural soils that receive sludge--almost regardless of the origin of the sludge.
8. Can't we replace the metals that are removed by crops with metals in the sludge?
Given the input and output from farmland, the metal addition to soil deriving from spreading sludge, which is presently permitted and officially claimed to be safe, is much, much higher than what the plants (if they are lucky) can or (if they are unlucky) do take up. That metals are removed from the land with the harvest does not justify disposing of sewage sludge on the land as the means of replenishing these metals: at least not if we mean to maintain a sustainable nutrient cycle, which must be based on the return of what has been taken out. Such a cycle requires that manure -- properly both human and animal --be spread on the land used for food and forage crops. NO metals should or need to be added beyond those deriving from human and animal excreta.
Besides the sustainability reasoning, the sludge contains several heavy metals that have no known beneficial place in the soil to begin with.such as Mercury, Cadmium and Lead -- these metals are only toxic and there are almost no reliable data under which circumstances they could become dangerous in the food cycle.
It is a minor part of the nutrients in the soil that is consumed by humans. Environmental protection should give priority to restructuring the manure fertilization to favor grain production and second make sure that the nutrients stay clean in their most sustainable cycle -- no mixture with other wastes, no great dilution with water -- this will greatly improve the balance and sustainability of our agriculture.
9. - Are metals not leaching out of our soils?
No, there is a very small portion that drain or leeches out of the soil, less than the addition through precipitated air pollution.
It is really important to realize how impossible (by any biological, chemical or mechanical method known today) it is to get heavy metals out of the soil once it is there i any significant concentration. This places the farm land in a unique and crucial situation -- if it is allowed to deteriorate or become poisoned, there is no return, no reversal.
10. - All sludge is not the same though - right?
There are variations in the sludge content from a big city vs. small rural areas and rural single-family septic tanks but the difference is surprisingly small. It is, however, a big difference between all these sludges and for example urine that has been source separated. This is where the demarcation line goes between nutrient deterioration and a sustainable bio-cycle --- not between different kinds of sludge.
11. - But the metal content in sludge is not much higher than in animal manure?
There is a fundamental difference between the metal in sludge and in manure. The heavy metals in manure comes from the land, is taken up by plants, makes a trip through the cow and come back to the land. The concentrations are yet not so high and it is relatively irrelevant what the actual number is -- the content in the soil stays reasonably unchanged. As long as the metal comes out of the soil (and no additions are supplied to the feed) the metals are returned to the soil. It presupposes that for example the practice of adding zinc and copper to the feed has to stop.
Sludge, however, contains almost no metals originating from farm land. Sludge spreading is therefore certain to accumulate heavy metals in the soils regardless of the concentrations and density of sludge application.
This is the fundamental system error which has not been taken into account when the government allow sludge to be spread based on similarities between sludge-metal and manure metal contents (and only in a few selected metals).
12. - Today, isn't the sludge almost clean after all the pollution reducing work in industry?
It used to be that industrial discharge was made responsible for all the "dirt in the sludge"...and a lot has been done to eliminate toxic discharge from process industries -- this is great regardless of where the remaining sewage goes. A sewer system, because of its convenience of disposal, still receives a multitude of dangerous substances. The difference between several years ago and now is that earlier the sewers could have continuos additions of acutely toxic materials by regular disposal. Now toxic input occurs in batches that are not even allowed but still the easiest and cheapest way to get rid of undesired substances. The sewage treatment operator still has no clue what will enter the treatment plant from one minute to the next. Whole batches of sludge can have very high concentrations from a batch discharge that can go totally undetected until it generates some damage --- many may never be traced since the effects occur with a long delay: lead, mercury, dioxins, radioactive materials etc. Another fundamental dilemma is that we have such a multitude of chemicals in circulation that there is no way to test for everything that can cause illness and damage.
So one of the most confusing flaws with the system is unpredictability -- we don't know what, we don't know when and we don't know what to do if something unusual comes in. Most of the time, batches of toxic chemicals passes through the plant undetected -- some portion goes out with the "treated water" the other is trapped in the sludge.
What is clean?
The table below show some industries in Sweden, that are connected to
Ryaverket(asewage treatment plant in Gothenburg, Sweden) The table
show the amount of COD (Chemical Oxygen Demand) from some of the big
industries in the region. COD indicate hard-to-digest compounds
discharged to the treatment plant -- these include many persistent
chemicals.
Greenpeace made an investigation in the mid 1980ies of the largest sources of COD discharge. According to the Yearly Report from Ryaverkets 1995 the amount of COD has increased from several of the largest sources.
Table - COD increase from sample industries in
Sweden AB Papyrus (paper) Pripps (brewery) Volvo Torslanda (cars) Tagene avfallsupplag (haz.waste
depot) Brudaremossens avfallsupplag (waste
depot)
The increase is a reasonable consequence of increased economic growth and the prosperity in the region during the last few years and logical since there is a single sewer network. So in spite of the increased discharge there are reports of less pollution in the sewage and the sludge. The pollutants that are monitored are for example (toluene, nonyl phenols, PAH and PCB). What if the measured chemicals have been substituted for substitute chemicals that does the job, are not on the list of pollutants but are as harmful and potentially damaging...? Since the focus and the laboratory routine is set up for particular chemicals, substitutions to chemicals not on the list would circumvent the law but not necessarily improve the situation...
13. - Those organic chemicals in the sludge can not cause harm to the food now that the sludge is approved by the EPA can they?
A "normal sludge" contains residues from the estimated tens of thousands of chemicals that are in circulation in today's society. The testing program that the sewage treatment operators are required to maintain cannot possibly test for even a fraction of these chemicals never mind the new ones formed by reactions between chemicals. They are neither analyzed nor are there any limits on how high their concentrations can be. This is not observing the carefulness principle. Only four organic compounds are measured and have limits but the limits are set to the factual average amounts measured and not according to any risk assessment. The prime objective is to get the sludge out on the fields. PCB is a very dangerous chemical which has given a much to high allowed limit. The Food and Drug Administration has made no assessments of what concentration of various chemicals in sludge as it impacts on food safety and health.
Example: Decline in brain function during the
fetus stage as a consequence of PCB in the mother's blood.
The tables below show the decline in attention in a seven month
old child as a function of increased PCB-concentration in blood
sampled in the umbilical cord according to Jacobson et al (USA). The
concentrations are very low and the shadow area represents the
concentration in Scandinavian women 1990 according to professor Ulf
Ahlborg. The damages remain after four years of age according to the
second table which shows the relationship between lowered memory in
the four year old as a consequence of the PCB exposure as measured in
the mother's blood (umbilical cord).
Problems in EPA's Testing Guidelines
Sludge contains PCB , dioxins plus almost everything else that has ever been manufactured by any chemical or pharmaceutical corporation in some, however small, concentration - this is the nature of the sewer system. This is expressed by another researcher: Project supervisor - Dr. Kofi Marfo, Special Education Department, University of South Florida, Tampa Florida as follows:
Problems in EPA's Testing Guidelines
Current chemical testing guidelines set by the E.P.A. requires the
chemical company to test their chemicals for health effects upon test
animals only one chemical at a time. This, unfortunately, is what
many scientists state is a serious flaw in judging the safety of a
chemical because this is not what our children are exposed to in the
real world. In fact, a child is subjected to hundreds of chemicals
simultaneously from chemical flavors and preservatives in food - to
chemicals in cleaning compounds - cosmetics - plastic vapors in
carpeting and upholstery - vehicle exhaust - and pesticides used in
schools and the home. Because of this wide range of exposures, it
would be necessary to test all these compounds simultaneously at low
levels to come up with any realistic estimate of health effects upon
our children - and this just isn't being done. http://www.chem-tox.com/pregnancy/learning_disabilities.htm
14. - But the concentration of PCB in sludge is not higher then PCB in fish and we EAT the fish !
This argument is a splendid demonstration of the misconception of the PCB problem. In Sweden, many children are very possibly exposed to much too high concentrations of PCB during pregnancy and it is possible that newborn babies have central nervous system damages from PCB. The mother get PCB from fish (high concentrations in fatty Baltic fish) and also from agricultural animal products that contribute even higher than the fish for normal food consumption. (See table re PCB)
PCB is likely to enter the food chain, primarily through animal feed. There is a pool of PCB in the air which is adsorbed/taken up by the skin of grass, grain crop etc. PCB is added to the air in a few different ways. One is through spreading of sludge on the farm land. A portion of this PCB can evaporate and therefore we get it into animal feed, grass and soon in the milk, cheese, eggs, poultry, meat etc. This chain of PCB proliferation is of course affecting all farming and gardening -- even rather far away from the vicinity of sludge farming -- even the gardening that has taken great care to stay organic. Grazing land is particularly sensitive to sludge applications as a grazing cow can ingest as much as several pounds of surface soil in a day.
15. - It will be too expensive to rebuild the sewage treatment systems !
The construction of the existing sewage systems has in Sweden been extremely costly and the result is not a viable system for a sustainable agriculture. Reconstructing this system will be expensive as well but the present system need replacement anyway since many of the pipes and culverts are in need of replacement even without new system technology in mind. Source separation systems are on-site and do not require an elaborate pipe network. Overall cost for waste collection and treatment tend to be around 90% for transportation portion of the systems (pipes, interceptors, pump stations, blasting and digging up roads...). This is the portion that can be dramatically reduced with new source separation technology.
Furthermore, it would be utterly cynical if we destroy our and future generations food production for economic reasons...
16. - What can we do with all the sludge if it cannot go to the farmland ?
The largest sewage treatment plant in Sweden is Ryaverket in Gothenburg. It has demand for almost all of its sludge for restoration work at building sites - landfills, roads etc. If sludge isn't used landscape architects and contractors will use chemical fertilizer to restore growth... better to use the chemical fertilizer on the farm during a transition period and sludge for landscaping than the other way around.
How can we replace sewer systems?
The following steps should be taken immediately:
Appendix
To our readers!
Copy and distribute this material to other interested parties... to your local, county and federal officials, to farmers, to consumer groups and agencies to whoever is receptive to what is about to happen if we do nothing !
Any questions, contact the author...
Sincerely,
Gunnar Lindgren,
PO BOX 1363,
S-446 00 Älvängen,
e-mail: gunnar.lindgren@ale.mail.telia.com
Table A. Chemical fertilizer is much cleaner
than sludge mg/kg (P) - ppm Heavy metal In urine Chem. fertilizer* Septic tank Sludge 95 Lead 31 ppm 24 ppm 3000 ppm 1700 ppm Cadmium 3 ppm 2 ppm 90 ppm 52 ppm Copper 300-3000 ppm 160 ppm 20000 ppm 17000 ppm Chromium 60 ppm 110 ppm 1300 ppm 1200 ppm Mercury 1.4 ppm 0.1 ppm 50 ppm 60 ppm Nickel 200 ppm 30 ppm 1000 ppm 600 ppm Zinc 640 ppm 150 ppm 53000 ppm 21000 ppm *NPK from Hydro Agri (which has 50% of
the Swedish fertilizer market)
Metal Lead 24 ppm 1700 ppm 75 times Cadmium 2 ppm 51 ppm 25 times Copper 160 ppm 16 900 ppm 100 times Chromium 110 ppm 1210 ppm 11 times Mercury 0.1 ppm 65 ppm 650 times Nickel 30 ppm 580 ppm 19 times Zinc 150 ppm 21 100 ppm 140 times
*NPK from Hydro Agri ( 50% of the Swedish fertilizer market)
**(SNV report 4423)
The average sludge is heavily contaminated compared to chemical fertilizers for all heavy metals. Besides what is shown here, the sludge has a high content of Iron, Aluminum, Manganese, and Cobalt. Further more the sludge often contains metals that are not even monitored or reported such as Silver, Platinum, Tin, Arsenic, et al.
Table B. The guidelines and regulations issued by the Sw. EPA do not protect the soils from accumulation of metals and the farm's impending destruction. (a new chemical dust bowl?)
Heavy metal Lead 200 mg/kg ts 600 times Cadmium 4 30 times Copper 1200 60 times Chromium 100 380 times Mercury 5 60 times Nickel 50 40 times Zinc 800 7 times
Comparison between the heavy metals contained in urine and feces and "allowable"heavy metals in sludge according to Report SNV 4251
This limits allow for a massive increase of the heavy metals entering farm land -- this is neither sustainable nor a cycle ! These limits are determined in order to make most sludges from large sewage treatment plants allowable for spreading on farm land ...
Several countries allow even higher amounts of metals to be spread on the farm.
(To the reader: compare the sludge data from your sewage treatment plant with the recyclable amounts in the left column!)
C. The increase of the greenhouse-effect driving gas Carbon dioxide is around 0.3% per year. The EPA allows a much more rapid increase of soil toxification.
In this table the yearly precipitation of metals to soils is added to the "allowed" metal contribution from sludge (according to SwEPA, VAV o LRF 1995). This is correlated with the total average content in soils.
Heavy metal Tot. amount Precipitated From sludge Total added Increase/year Increase/10yr g/ha g/ha & år g/ha & år g/ha & år Cadmium 550 0,7 1,8 2,5 0,5% 5% Copper 37 000 15 600 615 1,7% 17% Chromium 39 000 15 600 615 0,3% 3% Nickel 22 000 3 50 53 0,2% 2% Zinc 143 000 100 800 900 0,6% 6% Mercury 150 0,2 2,5 2,7 1,8 18% Lead 40 000 30 100 130 0,3% 3%
For Cadmium and Zinc the allowed rate of deterioration is larger than the greenhouse gas increase. For Copper and Mercury (maybe the two worst to be accelerated) a much faster rate of deterioration is allowed. For lead, chromium and Nickel a deterioration equal to the greenhouse effect is "allowed".
Note that the precipitated metal content is a lot less than what the authorities accept through sludge application. Remember also that around 90% of the heavy metal uptake is returned to the land in the form of animal manure and plowed in stubble.
(The very small amount which is contained in the urine and feces and is cycled through the sludge is not included in this calculation) se sid 11)
D. Factual damages to the land through repeated sludge application.
In many cases, heavier than usual sludge applications has accelerated the "allowed" rate of deterioration of some soil parcels, which gives us a preview of what is to come:
1. The SwEPA and the Agricultural University has investigated farm land which has received larger quantities than "recommended" . A big increase of the metal content is exhibited in the topsoil layer:
" In three of the investigated fields, the concentration of the heavy metals lead, copper, zinc, and cadmium doubled in the top soil. This is what we can expect to happen in around 100 - 200 years with the 'allowed' rates of application" (What will this decrease in general health cost us in general suffering and medical expenses)
"We do not know what effects this will have on the plant/root systems when sludge has been added under a long time."
(From "Facts about the environmental research", SNV March 1984) No further comprehensive research has been done.
2. Sludge tests at the Agricultural University (Uppsala, Sweden) show that the blue-green algae are sensitive and very significantly impacted by sludge. Their ability to fixate nitrogen is only 20% of the normal algae not exposed to sludge. Blue-green algae from sludge applied soils also grow much slower than do the unexposed ones. Nitrogen fixating bacteria are not doing well in sludge applied soils. Their capability to fixate nitrogen from the air is greatly reduced. Rhizobium-bacteria are coinhabitants with pea-plant roots and are important nitrogen fixating bacteria. Bacteria in the soil that received sludge were less capable to attach themselves to the roots and form nuggets. The amount of bio-mass in the soil was reduced.
(From "Facts from the Agricultural University, Soil/plants" No 11 1990)
3. From a sludge farming experiment in the county Dalarna, increased concentrations of heavy metals in the grain core were observed and the report says: "The increase may be within the margin of error but concerning copper and zinc the uptake is significantly higher with the higher sludge application."
(From "Nutrients in circulation - Ett Dala-projekt", 1993)
4. In a sludge farming experiment in Igelösa and Petersborg in Skåne (southern Sweden), increased concentrations of heavy metals are registered in both the soils and the grain/crop and ill effects of it.
Copper in the ground: "Greatly increased values from the sludge application in both tests."
Mercury in the soil: "Raised concentrations from increased sludge application at Igelösa. In Petersborg only from the highest application rate."
Zinc in the soil: "at Igelösa higher concentrations were measured from higher sludge applications."
Lead in the soil: "The latest test show the tendency towards higher concentrations in the soil and sludge application"
Cadmium in the soil: "...increased concentrations".
Regarding heavy metals in the grain, nickel is the metal where "the uptake has clearly increased with the sludge application". . When both chemical fertilizer and sludge have been used "there is a clear increase of concentrations just after the sludge application events".
Regarding soil microbiology tests the team observed "negative impact on the heterotrophic nitrogen fixation. This process has been demonstrated to be particularly sensitive to copper in the soil."
(From "Spreading of sludge on farm land", Malmöhus läns Hushållningssällskap et al 1994).
5. The US EPA has reported copper to be a metal which turns phyto-toxic (toxic to plants) in concentrations that are only a little higher than the useful amount. The Sw EPA in the report SNV 3623 says that Swedish soils could reach this level in as little as 75 years with "allowed" sludge application. Copper could be the most critical metal for the growth inhibiting qualities in sludge, since it is on the increase in all municipal and domestic sludges (copper piping is everywhere) and is moved out on soils in all municipalities. In Holland, Copper is added to hog feed to increase growth rate. At the same time some soils have been poisoned by the hog manure's high copper concentration. There are Dutch fields around hog farms that are completely infertile. In Sweden, Uppsala and Malmö, sewage sludge have extreme metal concentrations and the sludge is still spread.
Other heavy metals, toxic to soil microorganisms such as Zinc and Silver, the latter is not even monitored in Swedish sludges, are approved for spreading on the land in unlimited quantities. Even the metal Platinum (now spread through the exhaust from catalytic conversion in cars, has been approved for spreading on the land in spite of reports of high toxicity under conditions similar to how mercury becomes toxic(metal components of platinum is estimated 10 times more toxic than metal mercury)
All these damages are accumulative and will produce damages separately or have amplified effects when sludge with diverse content is spread. The damage will happen sooner or later when sludge is applied... most likely sooner since the accrued effect will lower immune defense in all organisms. Note that the accumulation will take place as long as the metals are not coming from/with urine and feces. Almost no metals disappear from the soils. With sludge applications the amounts will steady and irrevocably increase. It is the equivalent of marching towards a cliff -- if you take large steps or small you are heading towards disaster...
E. Heavy metals around the urban areas.
Since most of the sludge is dumped around and close to the production site, it is the farm land around the cities that run the largest risk of getting destroyed first. Transport economy determines that the sludge is not taken far away from the treatment plant (New York City is an exemption since NY regulations are strict enough to prohibit sludge spreading on NY state farms - instead it all goes to Texas by train where it is integrated with the cattle feed operations. [Oprah, here is a huge issue]). In Sweden, there are indications that "metal rings" (like ring roads) have developed around the big cities. Note that there is no further margin as far as Cadmium is concerned in Sweden and very likely many other areas such as the Hudson River basin. Kidney damages are already expected as a consequence of the sludging practice. The sludge is 25 times as loaded up with Cadmium as is chemical fertilizer (from Hydro Agri - the most commonly used fertilizer in Sweden). It is an absolute agricultural moral obligation to use the least Cadmium contaminated fertilizers in this situation.
F. Sludge is not a sustainable fertilizer even if waste dumps, run off and industrial sources were totally disconnected from the sewer system.
The problem is created the moment we mix urine and feces with large amounts of processed drinking water water. This water contains of course the "natural metal content" but also metals added through the processing at the water plants and the distribution systems (such as copper, iron, zinc and aluminum). Through hot water heaters and appliances, soldering etc. we get further lead, cadmium, nickel and chromium (especially from old corroding appliances/system). Stainless steel contributes iron, nickel, chromium and molybdenum (a metal that especially at high pH can cause sickness and death (see case studies). Stainless steel is prevalent in all household appliance use (washing machines, dishwashers, sinks, kettles, pots and pans, forks knives and in almost all industrial process equipment -- the quality of stainless steel varies a lot.)
Tap water is used in all sorts of different ways -- it flushes away all sorts of cleaning agents and metal fragments that goes to the sewage. Besides water use other chemicals makes their way into the sewers from odd sources (home photo laboratories, small workshops handling solvents, paints, cleaners, dentists [mercury]. clinics, auto repair - oils, PCB, garden sheds (pesticides), the list is only limited by our imagination.... we would have great difficulties to try to exclude them in a municipality . Most people feel that that's what the sewer is for... to clean up their messes. Let's call it unavoidable for now. Metals and dangerous organics then accumulate and concentrate into sludge. Some of the organic compounds break down in the sewage treatment process some change to the worse. Tencides from detergents, as they break down, may result in very small amounts of nonyl phenols that are very suspicious and little known other than being confused in the body with hormones i.e. the female hormone estrogen which has a relationship to breast cancer (which and how we do not quite know). Hormones are effective in number of molecules released in the body -- the nonyl phenols are present in drinking water about a thousand times that amount of natural hormone levels. What that means and how that affects us, we do not know either...what we do know is that the reported cases of breast cancer, cancer in general, reduced sperm counts in males, infectious disease (generally lowered immune defense), allergies (eczema, psoriasis etc.) -- all of this is getting worse fast and has reached epidemic proportions.
Ryaverket (the Gothenburg, Sweden sewage treatment plant, which is the largest treatment facility in Sweden) has done many flow and mass balance calculations regarding the heavy metals. Those reports reveal that the sources that have been given the blame of being the major polluters are in fact not the major sources. This is the official report from GRYAAB 1996:2
Table F. Distribution of metal from branch
industry shown as Kg/year by Rya . plant Branch Cadmium Lead Chromium Copper Mercury Nickel Zinc Waste deposits 0.3 1.8 9 37 0.04 15 60 Chemical Industry 1 17 15 34 3 17 279 Car manufacturing 0.5 26 18 68 131 276 Textile laundry 0.1 3 10 0.8 30 Plating industry 0.3 2 25 21 39 65 Rya Incoming 72 1350 1040 10100 38 1890 17800 Total from industry 2 50 67 168 3 206 710 -- as % of total 3% 4% 6% 2% 8% 11% 4%
The conclusion from this table is that it is the common, general sources of sewage that contributes the dominating amounts of heavy metals to the sludge.
G. It is the concentration of pollution from tapwater and general water use that creates the problem. Not even septic tank sludge is safe to use in the long run.
Even in a residential septic system, where urine and feces is mixed with tap water, the heavy metals concentrate in this sludge as well. The following data is from the SwEPA Re. Uppsala 1990, Härnösand 1994-95 and Lidköping 1996) show the heavy metals in sludges from septic tanks are no less polluted than the sludge from larger treatment plants. This if we calculate the metal concentrations compared to the phosphorous in the sludges and shown as ppm (parts per million) metal to phosphorous. The first column show the metal/phosphorous in the food and beverages as a normative value, assuming that this is what the "pure" urine and feces should show. These are theoretical values based on intake (SwFDA - SNV 4251 pg. 21). This is followed by a rather recent investigation done by the Agricultural University (Jönsson-96), where source separated urine with a small amount of flush water is included -- this is also reported as ppm metal/phosphorous.
Table G. Heavy metals in different forms of phosphorous from human urine and feces.
|
|
|
|||
|
Heavy metal |
Metal/Phosphorous in pure urine and feces |
Metal/Phosphorous in separated urine |
Metal/Phosphorous in septic tank sludge |
Metal/Phosphor. in sewage sludge |
|
Lead |
21 ppm |
31 ppm |
3000 ppm |
1500 ppm |
|
Cadmium |
7.2 ppm |
3 ppm |
90 ppm |
50 ppm |
|
Copper |
1100 ppm |
300 - 3000 ppm |
20000 ppm |
18000 ppm |
|
Chromium |
21 ppm |
60 ppm |
1300 ppm |
1300 ppm |
|
Mercury |
4 ppm |
1.4 ppm |
50 ppm |
60 ppm |
|
Nickel |
95 ppm |
200 ppm |
1000 ppm |
670 ppm |
|
Zinc |
6300 ppm |
640 ppm |
53000 ppm |
23000 ppm |
This shows the great difference between the purity between nutrients caught before it has been mixed with large quantities of tapwater (drinking water) and those that are not (the sludges). If the septic tank sludge is compared with the source separated urine, the contamination increases from 5 - 100 times for the different heavy metals. Furthermore, the sludge from the septic tank is comparable in its heavy metal pollution, in spite of its difference in connected sources. The numbers could of course be very different if a private source of water was used. (Better or worse)
It is significant that the measured values are of the same magnitude as the theoretical data. How much of the metals that are retained and accumulated in the body could be part of this discrepancy. Further discussions of this subject can be read in SNV report 4425.
It is however, evident that the mixing of excrement with large volumes of tap water makes the sludge unsustainable in itself. There is no other way to harvest the nutrients in a pure enough way to secure sustainability than to sort out the excrement prior to the sewer system.
H. Is this information widely known to the environmental authorities i.e. EPA?
According to the report SNV 4251 the metal content in an "ideal sludge" comes from a treatment plant that only accepts metals from the food and from drinking water (should be tap water). Assuming that only metals that have been taken from the land shall go back to the land (contained in urine and feces), EPA's ideal sludge would still result in accumulation of heavy metals as high as shown in the left column in table H. The right column shows the accumulation that presently takes place when all other sources are included.
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Lead |
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Cadmium |
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Copper |
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Chromium |
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Mercury |
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Nickel |
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Zinc |
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Cobalt |
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Manganese |
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Iron |
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Aluminum |
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*According to report SNV 4423
(For cobalt, manganese, iron och aluminum the analysis is taken from "what is in the sludge?" Sjökvist-Johansson SLL 52/85, since those values are not reported by the counties [kommunerna]).
This is further proof that the present sewer systems are founded on a fundamental error in the system design which we cannot correct as long as human waste is water-born. Even the sludge that the SwEPA defines as ideal, contains almost only metals that are NOT going into a sustainable cycle but is accumulated in the soil
Concerning the degree of separation of metals in the sewage treatment plant, the ideal case assumes 100%. Since the metals from either source(urine or metal plating) is separated to the same degree, the relationship between the different metals remain the same. The following table show the effectiveness of separation in Ryaverket 's reporting (the Gothenburg sewage treatment plant.)
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If we correlate the relationship between metals in the incoming water and degree of separation, there is no sign that the degree of separation changes with changing metal concentrations in this plant.
Neither have we found any evidence that there would be sludges that could have lower metal concentrations than the "ideal sludge" according to the SwEPA - which is useless as a fertilizer in a sustainable agriculture.
If anyone has other data to contribute in this discussion we would welcome such information and its premises.
I Replacing chemical fertilizer with sludge
The next table show the increased rate of accumulation of some metals in the farm land when we go through the transition from chemical fertilizer to sludge application. We will assume that the 10% of our total agricultural area surrounding the main rural areas will be the main recipient. Copper and mercury are the most critical metals in this scenario and they will increase dramatically.
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Heavy metal |
In urine |
Chem. fertilizer* |
Septic tank |
Sludge 95 |
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Lead |
31 |
30 |
3000 |
1700 |
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Cadmium |
3 |
2* |
90 |
52 |
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Copper |
300-3000 |
170 |
20000 |
17000 |
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Chromium |
60 |
1800 |
1300 |
1200 |
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Mercury |
1.4 |
2 |
50 |
60 |
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Nickel |
200 |
210 |
1000 |
640 |
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Zinc |
640 |
1250 |
53000 |
21000 |
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NPK from Hydro Agri (which has 50% of the Swedish fertilizer market) |
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J. Open eyes destruction of agriculture?
The indisputable accumulation of metals in the farmland which now is scheduled through the application of sludges is inexcusable. It is magnitudes higher than the air precipitation and the additions from chemical fertilizers. We have entered on a course, with open eyes, that leads us towards a sure irreversible toxification of our most valuable asset -- the food producing farm land. Its long term productive capabilities are now consciously jeopardized by the very authorities that were given the stewardship of our future environment and survival -- the Environmental Protection Agency ! The mechanism is to replace the contaminated chemical fertilizers with an even more contaminated sludge.
The five example cited above, demonstrate in different ways how the farmland is damaged by sludge application. We know that the measured metals and the not monitored metals CANNOT be removed when harm has struck. We are now setting the course that can ruin the possibilities for coming generations access to reasonably clean food. Even if the the metal concentrations should decline with time, they will NEVER comply with a requirement for a sustainable agriculture as long as sludge is applied on a regular basis.
The earlier we can rebuild this system, the less damage will we cause to ourselves the next and future generations
We know what we have to do. Let us begin now.
Table under construction
Bromides flame retardants Arsenic (pressure impregnated
wood) Copper (pressure impregnated
wood) Hormone mimickers (from
tencides) Iron salts (some treatment
plants) Asbestos Cobalt Aluminum salts (other treatment
plants) Asphalt Manganese Acrylic plastics (polyacrylamides)
thickeners Rubber from tires Platinum from catalytic
converters Silver Chlorine (some treatment
plants) Plastics Petroleum residues Aluminum Fluoride Organic tin compounds Amino acids Organic silicon compounds Chlorinated organics (broad
range) Cyanides
Following are the chemicals and substances that are present in municipal sludge or can be assumed to be present on good grounds. They are not monitored and have no disallowed limits.
Dioxins
Ftalater
(The humus generating substances with its origin in feces (difficult to decompose fibers) is only about 3% of the sludge pile (or about 10% of the dry substance) Other components are cellulose from paper and textiles and residual microorganisms ["dead bugs"]. It is, however, an open question whether fibers from a polyester T-shirt, pieces of rubber and fragments of acrylic plastics (polymers from the de-watering process) shall be accepted as humus generating substance in farm land... This is not commensurate with the notion of becoming "the cleanest agriculture in the world"
Acrylamid/ was the chemical that recently caused poisoning of water supply in the Hallandsåsen.
From "The flow of nutrients in Swedish agriculture".
by Olle Pettersson SLU
I jordbrukets kretslopp av växtnäring utgör urin och avföring en blygsam andel. Det är betydligt mer angeläget att den spärr som finns mellan djurgårdarna och spannmåls-gårdarna elimineras. Här finns väsentligt mer fosfor att hämta för växtodlingen än i det förorenade slammet. Både kalium och mullbildande ämnen saknas på det hela taget i slammet.
NOTE. There is as much phosphorous in manure as it is in chemical fertilizers now used in Sweden