Learning quality and treatment of groundwater, surface water

Groundwater and surface water are now commonly treated for daily life and production. Therefore, the need to treat groundwater and surface water is considered urgent to ensure health safety as well high quanlity for production activities. However, it is necessary to understand the quality and treatment of groundwater, surface water as well as apply appropriate methods to bring the highest efficiency.

1. Find out the quality and treatment of groundwater and surface water to meet the standards of domestic water for daily use and production

The purpose of treating water sources from wells, rivers, streams, ponds, lakes… is to achieve the domestic water quality for daily life  according to National Technical Regulation on Domestic water at QCVN 01-1:2018/BYT, then depending on each demand of other use  that maybe need further treatment

Specific regulations and guidelines have been mentioned in this Regulation, including sampling methods, sampling frequency, analytical standards, etc., which are very easy for management agencies, domestic water suppliers and also for users

We attach QCVN 01-1: 2018 / BYT for easier reference.

Bellow are some key points summarized from QCVN 01-1:2018/BYT.

1.1. Article 5. Testing of domestic water quality parameters

1.  All Domestic water quality parameters must be performed at a testing laboratory, a certificated organisation accredited in accordance with ISO/IEC 17025 and registered for testing activities according to the provisions of Decree No. 107 /2016/ND-CP dated July 1, 2016 of the Government stipulating the conditions for doing business in conformity assessment services

2. Domestic water quality parameters of Group A: All water supplying domestic water suppliers must conduct testing.

3. Domestic water quality parameters of Group B: The parameters to be tested shall comply with local technical regulations promulgated by the People’s Committees of provinces and centrally cities on the basis of selecting specific parameters , suitable to the actual conditions of the localit

4. Domestic water suppliers must test all quality parameters of groups A and B in the list of Domestic water quality parameters specified in Article 4 of this Regulation in the following cases:

a) Before going to the first time operating

b) After upgrading, major repair that has an impact on the production system.

c) When there is an environmental incident that threatens to affect domestic water quality.

d) When there is a risk in the production process that may affect the quality of domestic water or at the request of a competent authority.

đ) Every 3 years from the most recent test of all parameters.

5. Periodic testing:

a) Frequency of testing for domestic water quality parameters of group A: Not less than 01 time/month.

b) Frequency of testing for domestic water quality parameters of group B: Not less than 01 time/6 months.

c) Depending on the actual situation of the locality, the People’s Committee of the province or centrally cities may prescribe a test frequency higher than the frequency specified at points a and b of this Clause.

1.2. Article 6. Quantity and point of testing samples

1. Quantity of samples taken per test:

a) Domestic water unit for less than 100,000 people: Take at least 03 samples of domestic water.

b) Domestic water unit for 100,000 people or more: Take at least 04 samples of domestic water and for every additional 100,000 people, one more sample will be taken.

2. Sampling points: 01 sample at the treated water tank of the water supply unit before being put into the distribution pipeline network, 01 sample is randomly taken at the faucet used at the end of the distribution pipeline network, the The other samples is randomly collected at the faucet used on the distribution network (including water distribution vehicles such as tank trucks or water tankers).

3. Foragencies, units, apartment buildings, collective areas, hospitals, schools, and enterprises, areas with central water tanks: Take at least 02 samples, including 01 sample at the central water tank and 01 random sample at the faucet used. If there are 02 or more central water tanks, each tank takes at least 01 sample at the tank and 01 random sample at the faucet used.

4. In case of risk of water pollution or epidemic situation: It is possible to increase the number of water samples taken at different points for testing.

1.3. Article 7. Sampling method, test method

Methods of sampling and testing of domestic water quality parameters are specified in Appendix 01 of this Regulation.

===================

2. Learning quality and treatment of groundwater, surface water through general knowledge and deep expertise

Water is so important that it is indispensable role for anyone in life and production. Therefore, information related to water is both basic knowledge and highly specialized to be used in all fields.

We all was teached, storied The Water at “Science 4th grade” book about feeling, loving and protecting. In each area of expertise, water quality has been classified to standards that all must be followed to be licensed or certificated

Excerpt from the book 4th grade learn about water – love, use, protect our water

3. Characteristics of groundwater (well water)

Groundwater is a fresh water source, obtained from the ground, obtained from a traditional dug well without deep, or a drilled well with deeper layer (several tens of meters).

Currently, groundwater have been high polluted, especially in areas near the uncontrolled discharge sites such as Waste from industrial parks, handicrafts, craft villages… is discharged and seeped into the ground, affecting dug and drilled wells. Therefore, applying the suitable treatment to cleanify this water source into domestic water is an urgent matter to be done.

Studying the quality and treatment of groundwater, surface water has shown that the components present in groundwater have been affected from the following sources:

The natural geology of the land. For example: Limestone geology has high hardness, non-tight geology has high suspended dirt, and mineral areas have high heavy metals…

Infiltration from surface wastewater or harmful waste landfills: This is the main cause of pollution, in which organic and inorganic compounds from the industries of chemcial or related to chemical such as paints, dyes, pesticides,…are a major role in causing water pollutted and incurable diseases…Good management of this discharge will contribute to the protection of water sources, reducing the time and cost of groundwater treatment. On the contrary, it not only pollutes the water source, diseases but also makes it difficult, expensive, and even impossible to remove toxic substances from the soil.

Moving underground from another area to this location: Near the sea, it can be salty when the sea level rises or the groundwater level drops, groundwater flows through strata with high heavy metals…

Currently, the exploitation of groundwater has been legalized according to Decree 167/2018/ND-CP regulating the restriction of underground water exploitation, which clearly specifies which areas are allowed to exploit with the allowed amount.

The results of investigating the quantity of water consumption for domestic demand is just small amount while for industrial purposes and agricultural irrigation, it consumes a large amount of water. Therefore, in order to meet this demand, it is necessary changing to other sources, namely surface water such as rivers, streams, rain water, collect water from the air, recycle from treated waste water into domestic water or use it for many purposes

Causes of underground-water pollution

4. Surface water characteristics (rivers, streams, ponds, lakes)

Currently, heavily polluted surface water is easy to identify, can be based on signs such as: stench rising up; the amount of harmful microorganisms increased; COD, BOD, and suspended solids increased ; a big of fishes death due to the first rains of the season; Algae, plants grow rapidly on the surface of rivers, streams, ponds, lakes…

Not only the quality but also the quantity is significantly reduced, rivers and streams are depleted faster than before in the dry season, causing both water shortage and saltwater intrusion, causing a lot of problems and difficult for life and production.

Causes of groundwater and surface water pollution

Through understanding the quality and treatment of groundwater, surface water, the causes of water polluted and shortage are many. In order to limit pollution as well as reduce costs to cleanify having domestic water, it must be done synchronously, from consciousness to action of individual to public as well as law enforcement.

5. Treatment methods of groundwater, surface water and some water properties should be known

No	Basic properties	Well (underground) water	Surface water ( river, stream, lake )
1	pH acidity	Usually low due to dissolved CO2, areas with limestone for higher pH.	Neutral, little changed.
2	Fe, Mn Alum contained	Available in well water, varies by region, stratigraphic and seasonal.	Low
3	(Ca, Mg) Harndess	Varies by region.	High difference by amount of rainwater contacted to geology of each place.
4	Heavy metal	Usually found. More care to treat	Not high, but affected by wastewater, it will be very high.
5	Suspended solid, organic compounds	Usually low. Not tight geology maybe high.	Usually high, varied much at beginning of rainy season.
6	Unpleasant odor (due to H2S, NH3 ..)	Usually low, only a few wells are buried with decomposed organic matter will be high gases	NH3 varied much due to organic decomposition, H2S is usually low.
7	Khí, gas CO2	Usually high.	Low, due to changed to HCO-, CO32-
8	Khí, gas O2	Very low.	High, possibly saturated.
9	Arsenic (inorganic toxic)	Depends geologically or infiltrated from wastewater.	Low.
10	TDS and Chloride (salt)	Usually low but so high for salty well water	Will be high at beginning of rainy season or a large river near sea.
11	Microorganism	Only anaerobic bacteria but very low.	High to very high due to good growing conditions such as dissolved oxygen, nutrition, temperature.

6. Some common parameters directly related to health

If too dirty water, with sensory evaluation some abnormalities can be regconized detectly through color, smell, and taste. However, there are many other toxins in the water that can only be detected by specialized analytical equipment and the correct water testing method

Since water is a main part in the human body, from digestion to transportation of substances throughout all organs to perform metabolism, the direct effects from water to the body will immediately cause symptoms such as digestive disorders, stress, fatigue… to long-term harmful accumulation that are sometimes difficult to detect with manifesting as growth retardation, memory loss, decreased immune system, and other diseases. , even affecting life without being curable.

When studying the quality and treatment of groundwater and surface water, it is easy to see that there are many processes to treat polluted water for one or several criteria. Depending on the amount of water consumed and whether there is a need for further treatment for other higher needs, choose a treatment technology that is suitable for investment and operating costs.

For example: The same source of water contaminated with iron, but used for family with small capacity and for  Factory with  large-capacity, the processes for treating groundwater and surface water maybe different.

Here are a few common indicators, which can be recognized through the senses or a simple quick test.

6.1. pH

– It is not possible to guess the pH of water with the naked eye, but must use indicator paper or a testing machine

– Low pH has a sour or acidic taste, metallic fishy smell; High pH has a soda taste. Raise pH with suitable chemicals or degas CO2.

pH must be in allowable range ( 6.0 – 8.5 )

6.2. Iron (Fe²⁺, Fe³⁺)

– Iron Fe2+ contains light green light, can move in groundwater and oxidize to brick yellow color of Fe3+.

– Iron Fe3+ with yellow clings to objects that will be difficult to clean

Well water contaminated with healy iron and needs to be treated

– Unpleasant fishy smell.

–  Generall treatment methods are performed by oxidizing Fe²⁺ to Fe3+, settling, filtering, and absorbing ion exchange resins.

6.3. Manganese (Mn)

– Manganese comes from well water, brown color. Water contaminated with iron is also often contaminated with manganese.

Well water turns dark red brown when contaminated with manganese

– Unpleasant fishy smell.

– The methods of treating groundwater containing manganese are carried out by oxidizing, settling, filtering, and absorbing ion exchange resins.

6.4. Hardness (Ca, Mg)

– It cannot be sensed directly, but must be boiled or tested with a quick test kit, indicator or a specialized machine

Hardness causes deposits on the glass

– Use a rag to wipe the cup containing water, wait for the steam to evaporate, the remaining translucent layer may be due to calcium and magnesium. In addition, it is possible to monitor for a while, if the following conditions appear, the water source has been affected by hardness:

+ Lime on kettle

+ There is a change in color, smell, and taste of coffee, tea; less foam when soap dissolved in high hardness water

– If use high hardness water, long-term use see lime stick to the devices

– The methods of treating high hardness water are softener resin, cation resin, RO membranes. However, too low hardness (through RO membrane filter, ion exchange resin) is not good for the body.

6.5. Lead (Pb)

– Wastewater from the battery factories contains higher lead (including from dust) than be found in nature; lead ion also dissolved from the old metal pipe system has been rusted and rotted for a long time into water.

– To reduce high lead concentration in wastewater, can be coagulant flocculation, sedimentation then chelated with suitable chemical to to reach discharge limit. For water with low lead concentration, activated carbon can be partially absorbed, then RO membrane is used because it cannot be removed by oxidation or boiling.

– For lead from air dust, firstly collecting dust to clean it in Scrubber with water, and then continue taking it out from wastewater as just mentioned above

– Unable to recognize color, smell and taste if lead is contaminated in water. However, if the well water is contaminated with iron due to corroded steel pipes or corroded pipelines, it is necessary to check for lead toxicity or not, so that have a appropriate treatment method  applied

6.6. Arsenic (As)

– This toxin is very dangerous to human and animal health but difficult to detect because it is colorless, odorless and tasteless. However, often present together with iron and manganese.

– Be found in many different areas in groundwater, dissolved into water by oxidation of sediments and infiltration from pesticides, herbicides and industrial wastes (described in the figure).

Use water containing arsenic is harmful to health

– The methods of treating arsenic-containing groundwater are carried out by oxidation, sedimentation, filtration, absorption of activated carbon and other filter media. RO membrane or Ion exchanged resin also used to completly removal.

– Can be quickly tested with on-site test kits. Periodic measurements should be made at centers with highly specialized equipment.

7. Organic matter and other related impurities in water (TC, COD, BOD, TDS, SS…)

Surface water polluted

– Mainly occurs in surface water (rivers, streams) rather than groundwater.

– There is a bad smell due to containing H2S, NH3 … decomposed from plant, animal, discharge system.

– High turbidity, suspended dirt.

– Decompose into NH4+, NO2-, NO3-.

– Comes with very high microbiology.

– The treatment is oxidation, sedimentation, filtration, sterilization (please refer to the technological process of treating river water into domestic water).

7.1. Chloride – Salty water

– Salt water is still odorless and colorless.

– Very easy to recognize with salty taste.

Salty water must be treated to use

– River near sea or groundwater in coastal areas is susceptible to seasonal salinity.

– Saline water cannot be used directly or indirectly for humans, livestock, agriculture and even industry

– Applying methods to treat saline groundwater or surface water is quite expensive because it is necessary to use RO membranes or negative ion exchange resins, distillation. Using rain water with periodic disinfection is a safe solution for water sources in the time needed for family activities.

7.2. Bacteria, virus

– It is very difficult to detect visually, in some cases, the smell may be noticed, but at that time, it has been heavily infected.

– Surface water is heavily bacteria virus contaminated, groundwater is mainly iron-corrosive bacteria.

– Water that has not been disinfected before making ice still contains high bacteria, virus

Ice still contains high risk of bacteria

– To kill bacteria is not difficult; there are many different ways, depending on the amount of water used such as:

• Boiling to kill 100% bacteria is a common form in every family. However, after boiling, it does not last long because it will re-infection from the air.
• Use UV lamp, Ozone machine and need circulating to ensure totally killed
• Use chemical tablets: Chlorine and chlorine compounds.

7.3. Bad smell, strange taste

– Less or more of any color of water showed that being polluted because normal water must be colorless, odorless and tasteless. Among them, the above mentioned pollutions can be expressed more or less by the color of the water.

– Colorless water but has a strange smell and taste is also pollution contaminated.

– Strange smell and taste almost be together.

– Causing of smell and taste has many reasons that need to be studied then to have good treatment solution

No	Smell, taste	Mostly be found
		TC	NM	NN
	Note:TC = Dosmestic water or City water NM = Surface water; NN = Underground water
1	Domestic water with bad smell, possibly from amount of biocide of Chlorine, Chloramine B … still high. Chlorine is easy to recognize due to its characteristic odor.	*
2	Sour taste caused by low pH.			*
3	Fishy smell is a metallic smell, mainly caused by Fe and Mn in groundwater, often  brick – brown color accompanied			*
4	Bad odor caused by NH3 gas decomposed from protein-rich organic matter such as seafood industry.		*
5	The smell of rotten eggs is H2S,  caused by decomposing of organic matter or SO4 compounds by anaerobic			*
6	Salty taste due to saline water (so high chloride or TDS) occurs depending on season.		*	*
7	Other unusual tastes and smells are caused by microorganisms or existing contaminants.	*	*	*

Table : QCVN 09-MT: 2015/BTNMT National Technical on Groundwater quality

Table : Maximum value of ground water quality parameters

No	Parameters	Unit	Limit
1	pH	–	5,5 – 8,5
2	Pemanganat index	mg/l	4
3	Total dissolved solids (TDS)	mg/l	1,500
4	Total hardness (calculated as CaCO3)	mg/l	500
5	Ammonium (NH4+ tính theo N)	mg/l	1
6	Nitrite (NO-2 tính theo N)	mg/l	1
7	Nitrate (NO-3 tính theo N)	mg/l	15
8	Chloride (Cl-)	mg/l	250
9	Fluoride (F-)	mg/l	1
10	Sulfate (SO42-)	mg/l	400
11	Cyanide (CN-)	mg/l	0,01
12	Arsenic (As)	mg/l	0,05
13	Cadmium (Cd)	mg/l	0,005
14	Lead (Pb)	mg/l	0,01
15	Chromium VI (Cr6+)	mg/l	0,05
16	Copper (Cu)	mg/l	1
17	Zinc (Zn)	mg/l	3
18	Nickel (Ni)	mg/l	0,02
19	Manganese (Mn)	mg/l	0,5
20	Mercury (Hg)	mg/l	0,001
21	Iron (Fe)	mg/l	5
22	Selenium (Se)	mg/l	0,01
23	Aldrin	µg/l	0,1
24	Benzene hexachloride (BHC)	µg/l	0,02
25	Dieldrin	µg/l	0,1
26	Total Dichloro diphenyl trichloroethane (DDTs)	µg/l	1
27	Heptachlor & Heptachlorepoxide	µg/l	0,2
28	Total Phenol	mg/l	0,001
29	Total radioactivity α	Bq/l	0,1
30	Total radioactivity β	Bq/l	1
31	Coliform	MPN hoặc CFU/100 ml	3
32	E.Coli	MPN hoặc CFU/100 ml	Not detected

Table : QCVN 08-MT: 2015/BTNMT National Technical on Surafce water qualit

 Table: Maximum value of surface water quality parameters

No.	Parameter	Unit	Maximum value
			A		B
			A1	A2	B1	B2
1	pH		6-8,5	6-8,5	5,5-9	5,5-9
2	BOD5 (200C)	mg/l	4	6	15	25
3	COD	mg/l	10	15	30	50
4	Dissolved oxygen (DO)	mg/l	≥ 6	≥ 5	≥ 4	≥ 2
5	Total suspended solids (TSS)	mg/l	20	30	50	100
6	Ammonium (NH4+ tính theo N)	mg/l	0,3	0,3	0,9	0,9
7	Chloride (Cl-)	mg/l	250	350	350	–
8	Fluoride (F-)	mg/l	1	1,5	1,5	2
9	Nitrite(NO-2 tính theo N)	mg/l	0,05	0,05	0,05	0,05
10	Nitrate (NO-3 tính theo N)	mg/l	2	5	10	15
11	Phosphate (PO3-4 tính theo P)	mg/l	0,1	0,2	0,3	0,5
12	Cyanide (CN-)	mg/l	0,05	0,05	0,05	0,05
13	Arsenic (As)	mg/l	0,01	0,02	0,05	0,1
14	Cadmium (Cd)	mg/l	0,005	0,005	0,01	0,01
15	Lead (Pb)	mg/l	0,02	0,02	0,05	0,05
16	Chromium VI (Cr6+)	mg/l	0,01	0,02	0,04	0,05
17	Total chromium	mg/l	0,05	0,1	0,5	1
18	Copper (Cu)	mg/l	0,1	0,2	0,5	1
19	Zinc (Zn)	mg/l	0,5	1,0	1,5	2
20	Nickel (Ni)	mg/l	0,1	0,1	0,1	0,1
21	Manganese (Mn)	mg/l	0,1	0,2	0,5	1
22	Mercury(Hg)	mg/l	0,001	0,001	0,001	0,002
23	Iron (Fe)	mg/l	0,5	1	1,5	2
24	Active substances	mg/l	0,1	0,2	0,4	0,5
25	Aldrin	µg/l	0,1	0,1	0,1	0,1
26	Benzene hexachloride (BHC)	µg/l	0,02	0,02	0,02	0,02
27	Dieldrin	µg/l	0,1	0,1	0,1	0,1
28	Total Dichloro diphenyl trichloroethane (DDTs)	µg/l	1,0	1,0	1,0	1,0
29	Heptachlor & Heptachlorepoxide	µg/l	0,2	0,2	0,2	0,2
30	Total Phenol	mg/l	0,005	0,005	0,01	0,02
31	Total oils & grease	mg/l	0,3	0,5	1	1
32	Total Organic Carbon, TOC	mg/l	4	–	–	–
33	Gross alpha activity a	Bq/l	0,1	0,1	0,1	0,1
34	Gross beta activity b	Bq/l	1,0	1,0	1,0	1,0
35	Coliform	MPN or CFU /100 ml	2500	5000	7500	10000
36	E.coli	MPN or CFU /100 ml	20	50	100	200

Remark:

The classification of A1, A2, B1, B2 for surface water sources to assess and control water quality the various purposes of water use, sorted by descending quality level.

A1 – Use for domestic water supply purposes (after applying conventional treatment), conservation of aquatic plants and for other purposes such as type A2, B1 and B2.

A2 – For the purpose of domestic water supply, but must apply appropriate processing technology or the purpose of use as type B1 and B2.

B1 – For irrigated agriculture, irrigation purposes or other purposes which require the same water quality or purposes as type B2.

B2 – Waterway transport and other purposes with low quality of water requirements.