Archive for the ‘water pollution’ Category

Water quality – its Basic!

Saturday, December 24th, 2016

Its December and in South Gippsland our creeks have slowed to little more than a trickle. Like many rural properties we have to rely on water stored in dams to get us through to Autumn. Our garden and nursery stock put extra demands on our supplies, and of course the cows are always thirsty!

Around the farm we use rainwater tanks for the house and dam water for the cows. We also need water to wash down the dairy. For that we keep back and recycle rinse water but use dam water as well. In the dairy we need better quality water for washing down milking machines and for feeding to calves. For this we use rain water supplemented with treated dam water.

Through Summer as water levels fall, dam water comes under many stresses. This shows up as changes in pH, oxygenation, build up of nutrients and salts, turbidity and organic matter levels.

Farm dam at low water level in Summer

One of our dams at low level during Summer of 2015. As water level drops basic water quality can change and is shown by factors like clearness, oxygenation, pH, salts and nutrients.

Where does water come from for your farm or rural property? Are you getting the right quality for the right use?

A water test can be a good first step to get your water supply right. It can tell which supplies can be used in different parts of the farm. A test can also pick up changes in water quality or even hazards in the water.

There are many options to treat water so that it can be used in more critical applications. At Apps Laboratories we provide the testing that gives a start in improving your water quality.

Our Basic water quality test is designed to test for around 9 critical water quality factors. We do the tests in our own lab – on our farm.

No you won’t be left with a report that makes no sense because we highlight all the key issues and talk about the possibilities for your water in a way that ‘normal folks’ understand because we know that’s what you expect.

Our Basic water quality test is good for tank water, dams, springs and bores.

To get your water tested is easy. Just go to our appslabs.com.au How to order page for instructions on collecting and posting samples.

Effluent management on a dairy farm

Saturday, November 9th, 2013

For the last few weeks I’ve been visiting a dairy farm in West Gippsland to learn a bit more about how dairy farms work. It’s also an opportunity to apply some ideas about soil and water management in a practical context.

Cows can deposit around 8 – 10% of manure and urine output around the milking shed and yards. Manure and urine contains significant amounts of major nutrients including nitrogen, phosphorous and potassium.

On many farms this manure is often washed directly into specially contructed waste retention dams. A typical setup is a sedimentation dam sometimes followed by an aeration dam.

Sedimentation dam for dairy waste on a farm in West Gippsland. Water is washed into the dam from the milking shed and yards without treatment.

Sedimentation dam for dairy waste on a farm in West Gippsland. Water is washed into the dam from the milking shed and yards without treatment.

The picture shows a sedimentation dam on the WG farm. There is a thick crust of manure on top which means that conditions in the dam are most likely anaerobic. At this dam I didn’t want to get too close in case I became part of the waste system! Therefore I didn’t get a sample!

In an anaerobic dam the organic matter itself provides oxygen to help drive the other processes that eventually break down most of the organic matter into methane, hydrogen, carbon dioxide and ammonia. But the disadvantage of this method is that energy in the organic matter is lost (as methane) and importantly nitrogen is lost (as ammonia).

The overflow from the sedimentation dam on the farm enters a second aeration dam. What can we expect the water quality to be in this type of dam? There shouldn’t be much nitrogen but what other nutrients will be present?

Dairy farm aeration dam in West Gippsland. Water flows into this dam from an uphill sediantation dam that takes waste directly from the dairy.

Dairy farm aeration dam in West Gippsland. Water flows into this dam from an uphill sedimentation dam that takes waste directly from the dairy.

The aeration dam is just below the sedimentation dam. The overflow pipe can be seen in the picture. The water has a brown colour and a slightly unpleasant smell. Here are some water quality tests done in the Apps Labs lab: Dissociated carbon dioxide 13.5 ppm (elevated); Turbidity (unfiltered) 57 FTU (high); Turbidity filtered (0.45 micron) 19.8 FTU (still high); pH 7.1 (very slightly on the alkaline side); UV absorbance 99.2% (very high dissolved humic materials); Conductivity 1459 microS/cm (elevated salts); redox potential (ORP) -44.7 mV (anaerobic, and that’s at the surface).

Nitrate and nitrite were checked using screening tests. Both were at low levels or absent. That’s expected anyway because nitrates usually don’t exist in low oxygen conditions and nitrites usually form from nitrates under reducing conditions. Phosphate was checked using two different test kits. One showed phosphate over 30 ppm. The other showed phosphate as 43 ppm. Both these levels are very high.

There may be significantly more phosphate present in the two dams than the amount measured as some is likely to be held in the sediments.

What about nitrogen? Ammonia – nitrogen in the aeration dam was 0.44 ppm. This is higher than normally found in natural waters but is not excessive. At pH 7 around 0.4% of this nitrogen can be expected to be in the ammonia form as opposed to the ammonium form. This is not good for water life because the ammonia form is harmful. In general as water becomes more alkaline, an increasing amount of any total ammonia nitrogen present is likely to be in the ammonia form. This same amount of ammonia nitrogen, is roughly equivalent to 2 ppm nitrogen as nitrate. This is slightly elevated for natural waters so the nitrogen in the ammonia form probably doesn’t account for all the nitrogen in the original manure entering the two dams.

What is the best way to use dairy effluent to capture maximum nutrient value?

The following web resource provides detailed figures on tests done on dairy effluent dams and suggests way to reuse the nutrients in the effluent:

DPI Victoria 2013, Using dairy effluent as a fertilizer. Downloaded from http://www.dpi.vic.gov.au/agriculture/dairy/pastures-management/fertilising-dairy-pastures/chapter-13, November 2013.

Water pollution case study

Wednesday, February 16th, 2011

Contamination of waters by organic matter including manures is a type of water pollution. Excessive organic matter load in water is likely to cause a number of changes including:

Higher turbidity
High decomposition rate leading to elevated carbon dioxide and lowered oxygen,
Undesirable intermediate products of decompostion including nitrite and ammonia.
Elevated nutrient levels
Elevated dissolved organic matter
Elevated bacteria levels in general and specifically E coli if manures are present

The owner of this dam on a property north of Melbourne noticed an unpleasant smell coming from the dam. The water was also very discoloured.

Farm dam polluted by runoff. The owner has already fenced off the water to exclude stock.

Farm dam polluted by runoff. The owner has fenced off the water to exclude stock. But what is the source of the contamination?

Here are the test results for this dam: pH 6.8, ORP 217 mV (low end of desirable range), turbidity 624 FTU (very turbid), UV absorbance 40% at 1 : 25 dilution (very high), ammonia + ammonium 12.4 mg/L (high), carbon dioxide (dissociated fraction) 25.6 ppm (high), nitrate 8.9 mg/L (slightly elevated), nitrite 0.16 mg/L (any nitrite is undesirable), phosphate 16.9 mg/L (very high), E coli 13,100 CFU’s / 100 mls (very high), aerobic plate count 2,067,000 CFU’s / 100 mls (high).The indications are that there is an organic matter contamination problem – because of the E coli, probably from manure.

Here are the results from the drain in the foreground of the photo: pH 6.9, ORP -33 mV (very low, indicates low or depleted oxygen)), turbidity 976 FTU (very high levels of semi suspended particles), UV absorption 53% (high, at 1 : 25 dilution), ammonia 26.3 mg/L (high), carbon dioxide 42 ppm, nitrate and nitrite both 0, phosphate 27.3 mg/L (very high), E coli 14,900 CFU’s / 100 ml, aerobic plate count 1,553,000 CFU’s / 100 ml.

My brief interpretation: Decomposition in the runoff water is producing ammonia and carbon dioxide. As the water reaches the dam oxygenation levels increase slightly allowing some nitrate to be produced. However there is not enough oxygen to convert all the nitrogen decomposition products to nitrate hence there is some nitrite detectable in the water.