Waste water monitoring

QCVN are certified to the monitoring conditions according to Vimcerts 197 on wastewater sampling field.

QCVN directly collect and store samples and analyze them in the laboratory of waste water, such as:

– Industrial wastewater monitoring

– Monitoring domestic wastewater

– Medical wastewater monitoring

The techniques for collecting and preserving wastewater samples as follows:

1. Standards specify the sampling and storage program for wastewater samples. (phương pháp lấy mẫu nước thải)

• TCVN 5994:1995 – Water quality ; How to get water sample; Guidance on sampling of natural and artificial ponds.
• TCVN 5997:1995 – Water quality; How to get water sample; Guidance on rainwater sampling.
• TCVN 5998:1995 – Water qualityc; How to get water sample; Instructions for taking seawater samples.
• TCVN 5999:1995 – Water quality; How to get water sample; Guidance on wastewater sampling.
• TCVN 6663-1:2011 – Water quality; How to get water sample; Instructions for setting up a sampling program.
• TCVN 6663-3-5:2009 – Water quality; How to get water sample; Part 5: Guidance on sampling of drinking water from a treatment plant and piping distribution system.
• TCVN 6663-6:2008 – Water quality; How to get water sample : Part 8- Guidance on sampling at Rivers and Streams.
• TCVN 6663-11:2011 – Water quality; How to get water sample : Part 11- Guidance on groundwater sampling.
• TCVN 6663-1:2011 – Water quality; How to get water sample: Part 1: Instructions for repeating the sampling program.
• TCVN 6663-3:2008 – Water quality; How to get water sample: Instructions for handling samples and storage of samples.

2. General content to support sampling program design:

• The objective of the wastewater sampling program:

1. To study the effect of discharges on a body of receiving water, including water overflows due to incidents.
2. To determine the effectiveness of each efficiency in a processing system.
3. To check the overall processing efficiency of the system.
4. To control the concentration of substances after treatment.
5. Test water quality to use for daily meals, or watering plants….

• Locate the location of water sampling:

1. The location of sampling depends on the objectives of the sampling program and the specific conditions of each monitoring location.
2. Based on the requirements of the objects that need to be monitored, such as wastewater treatment systems, rivers, streams, lakes, etc., we select and build appropriate monitoring points.
3. The selected sampling location must be representative of the object under observation.

• Determine specific parameters to support the selection of sample storage methods, on-site sample handling, test sample volumes and appropriate transit times:

1. Each water source, each type of production will generate a number of different specific pollution parameters.
2. The parameters selected depend on the purpose of the study and the purpose of that water.
3. Basis for selecting reference parameters to refer to according to the Circular 07/2007/TT-BTNMT and 04/2012/TT-BTNMT.(Establish criteria for determining the basis of environmental pollutants including waste water, emissions, noise, vibration, according to professions and production activities arising out of environmental waste source).
4. Based on the above, to select a sampling device and to hold samples to suit each object:

• Sampling device: Includes sampling device such as : stratified sampling equipment for deep waters, buckets, laces, protective gear, gloves…
• Sample container:

1. Sample selection elements: rugged, easy to cover, heat resistant, reasonable weight and volume, easy to clean and reuse, low cost, avoid loss of volatile samples, avoid contamination due to foreign substances in the sample container material.
2. A plastic container should be used for sampling wastewater. Some cases of using glass jars such as analysis: Greases, Hydrocarbons, detergents, pesticides.
3. If the sample has been sterilized to use sterile containers.
4. The sample containers used for microbiological testing must use bottles that withstand high temperatures, the materials of which do not release chemicals that inhibit the survival of microorganisms.

3. Water sampling technique:

         General principles:

• Water samples are taken depending on the purpose was fixed in advance, to ensure representativeness, the preservation depends on the parameters to be analyzed because each parameter preservation respectively to minimize the error between the actual and laboratory.
• For rivers, lakes and reservoirs of waste water: normal water samples are taken at a depth of 20-50cm from the water surface, taken at the most representative position, when the water depth is over 3m, it should be taken in stratified form and mixed together.
• For flow, the sample is taken in the area with the best disturbance to ensure the most homogeneous and representative..
• Samples are taken close to the surface to analyze emulsions, scum oil, floating substances.
• For microbiological parameters: bottles must be sterilized, the volume of sample collected in the bottle is about ¾ of the bottle capacity.
• Sampling at sewers, manholes: before proceeding, it is necessary to clean the sampling location to remove sediment, sludge of VSVs on the walls, select the point with strong eddy current to have a good mixing.
• Sampling in natural artificial rivers, streams and lakes:
• Sampling locations:
• Take samples from the bridge.
• Sampling in the middle of stream.
• Sampling near the coast.
• Take samples from the boat.

        Operations:

• Rinse the sampling device and sample container with the same sample background.
• Taking samples below the surface of the water 25cm, the sample bottles are immersed directly in the water for sampling, but avoid surface water unless special requirements for analysis of grease or light liquid criteria are required than water.
• Fill the sample container fully, to expel all air, to seal, encode the sample and to preserve it in the correct manner, for analytical criteria such as hydrocarbons, phenols, and plant protection chemicals that do not fill the flask pattern.

        Sampling locations:

• Sampling in sewers and manholes.
• Sampling at the pipe out of the waste water treatment system.
• Sampling at stages of processing system.
• Number of samples and sampling time:

Depending on the purpose to perform single and combined sampling.

• Single sample: determination of the composition at a given time for the waste source with little change in composition and volume.
• Composite samples: When evaluating the mean water quality, composite samples must be used.
• Sampling drinking water, food processing from treatment stations and water pipes (Arcording TCVN 663-5:2009).

      Sampling locations:

• Water storage tank (including water tower).
• Purify water factory.
• Water distribution system.
• Water supply hose before use.

      Operations:

• Clean, disinfect, and rinse the sample container.
• For sampling faucets, clean the hose and disinfect using a reference alcohol lamp flame ( ISO 19458).
• Drain the water for about 2-3 minutes at constant temperature.
• Proceed to approximately ¾ volume of the sample bottle, allowing it to mix well when analyzing.
• Encrypt the sample and specify the necessary information.
• Proceed to preserve the sample in accordance with the method.

      Sampling sea water:

• Sampling locations:
• Sampling offshore.
• Coastal sampling.

4. Sample preservation techniques

• Reference standard: TCVN 6663-3:2008 replace by TCVN 5993:1995.
• Lưu ý trong việc bảo quản mẫu:

        Samples for simple physical and chemical analysis of the sample, the sample should be filled with a stopper and a stopper to limit the effects of oxygen in the air, changing the composition of the sample.

        The microbiological identification sample is the opposite, it is necessary to leave an air space after closing the lid.

SUMMARY OF SAMPLE STORAGE METHODS

 

• Cryopreservation method:

Specified parameters	Container	Sample loading volume (ml)	Preserving techniques	Maximum storage time	Note
BOD	P/G	1000 full size	Cooling to 1-5oC	24 hours	Keep in the dark
BOD	P		Freezing-20oC	1 month	6 month( 1 month if BOD <50mg/l)

 

• Acid preservation method: phương pháp lấy mẫu nước thải

Specified parameters	Container	Sample loading volume (ml)	Preserving techniques	Maximum storage time	Note
Organic halides (AOX)	P/G	1000 full size	Acidify the sample to pH 1 to 2 with HNO3	5 days	Store samples in the dark and refrigerate from 1 to 5 ° C
Aluminum	P/G/BG rửa được với Axit	100		1 month
Bari		100
Cadimi		100

 

• No need to preserve:

Specified parameters	Container	Sample loading volume (ml)	Preserving techniques	Maximum storage time	Note
Clorua	P/G	100			1 month
Florua	P but not PTFE or glass	200

 

• Preservation techniques to determine many parameters:

Preserving techniques	Parameters apply	Inappropriate parameters apply
Acidify the sample to pH 1 to 2 with HNO3	Alkali metals, alkaline earth. Heavy metals except mercury. Organic halides are easily absorbed (AOX). Aluminum, antimony, arsenic, barium … total hardness.	Cyanua, Sulfua, Cacbonat,hydrocacbon,bicacbonat,nitrit. Soap and ester…
Acidify the sample to a pH of 1 to 2 with	Acid herbicides Antimon Arsen Chlorinated solvents Hydrocarbons, Iron, Nitrates, Greases.	Cyanide, Silver, Thali, Lead, Mercury (II)
Acidify the sample to pH from <4 with H3PO4	Phenol	Cyanua
Frozen -20oC	Anions, NH3, NH4, BOD, COD, pesticides, total nitrogen, phosphorus, biological tests, toxicity tests.

Note:

• P: plastic (Polyetylen, PTFE (politetrafluoroethylene), PVC (polyvinyl choloride)..
• G: Glass, BG: borosilicate glass.

IMAGE OF WATER SAMPLES BY QCVN