Nước thải là gì – Nguồn gốc, thành phần và cách xử lý nước thải

What is wastewater?

Wastewater is defined as water whose characteristics have changed after use by human activities such as domestic activities, industrial production, agriculture, healthcare… Pollution components in wastewater makes it toxic and can no longer be used directly.

There are 3 main sources of wastewater generation:

From people’s daily activities

Industrial production activities

Residential areas, urban areas, densely populated areas

Almost all of our activities generate wastewater. Going to the toilet, washing clothes, cooking, and bathing all produce domestic wastewater. Factories also release large amounts of polluted water. Rainwater flows through urban areas, carrying dirt and dust, which also turns into wastewater.

Composition of wastewater

What are the ingredients in wastewater? What are real examples? Wastewater has many different organic and inorganic components, including:

The concentration of these components will determine the level of pollution and how wastewater is treated.

Heavy metals are the main components of wastewater

What do wastewater indicators mean?

1. What is wastewater cod index?

Wastewater COD is the amount of oxygen needed to oxidize pollutants in wastewater. This is classified as an important index group, often specified in Vietnamese technical regulation documents. COD represents the pollution level of wastewater, indicating the amount of organic substances in water decomposed by bacteria and microorganisms. The higher the COD index, the more polluted the water source is and vice versa.

2. What is ammonium in wastewater?

Ammonium in water is a contaminant caused by animal waste, sewer discharges or contaminated water. When the amount of ammonium in food is higher than the standard, the water source will be polluted and contain many disease-causing bacteria and viruses. That’s why measuring and testing ammonium in wastewater is extremely important.

3. What is wastewater BOD index?

The BOD index helps us identify the level of life of organic microorganisms present. Thanks to that, experts can evaluate the level of decomposition of organic substances in the water environment. The greater the BOD, the more contaminated the wastewater is and vice versa.

COD index

Wastewater classification in Vietnam

After being asked what wastewater is, surely many of you wonder what types of wastewater are there today? Specifically as follows:

1. Domestic wastewater

This is the type of wastewater most familiar to us. Domestic wastewater includes:

Wastewater includes from toilets and bathrooms

Wastewater from the kitchen (washing dishes, washing vegetables…)

Wastewater from washing clothes

Domestic wastewater contains many organic substances, nutrients and pathogenic microorganisms. This type of wastewater needs to be treated before being discharged into the environment.

Domestic wastewater

2. Industrial wastewater

Industrial wastewater arises from industrial production facilities such as:

Food processing factory

Textile and dyeing factory

Paper factory

Chemical factory

Cattle and poultry slaughterhouse

The composition of industrial wastewater is very diverse, depending on the industry and production process. Industrial wastewater often contains many toxic substances and heavy metals, causing serious pollution.

Industrial wastewater

3. Urban wastewater

Urban wastewater includes domestic wastewater and a portion of industrial wastewater. In addition it also includes:

Rainwater on the street

Water leaks from the landfill

Wastewater from schools and hospitals

With the characteristics of dense population and many activities, urban wastewater has a very complex composition and has many potential risks of pollution.

Urban wastewater

Impact of wastewater on daily life

What negative impacts does wastewater cause to the environment and humans? Let’s explore its two main consequences.

1. Groundwater pollution

When wastewater seeps into the ground without treatment, it seeps into the aquifers. This is the source of domestic water for many households and production facilities. Poisoned groundwater will cause serious consequences:

Destroying the underground ecosystem

Depleting and degrading groundwater resources

Causes disease in humans and animals when using groundwater

Severe impact on agriculture and industry

2. Impact on human health

Wastewater directly or indirectly causes a series of health problems for humans:

Infectious diseases such as diarrhea, cholera, typhoid, hepatitis A

Skin diseases such as fungus, scabies, pimples

Food poisoning caused by eating contaminated vegetables and seafood

Cancer, fetal malformations, weakened immune system due to exposure to toxic chemicals

Wastewater directly threatens our development and quality of life. There needs to be fundamental solutions to control and handle it.

Wastewater pollutes underground water sources

The most popular wastewater treatment solution today

To minimize the negative impacts from wastewater, we need to apply a number of solutions such as:

Construction and upgrading of wastewater treatment systems: Investing in new construction and renovation of wastewater treatment plants to ensure capacity and quality. Classify and treat each type of industrial and domestic wastewater separately.

Enhance technology and processing techniques: Apply advanced technology, modern equipment and optimal processing processes. Strictly control input and output water quality, complying with environmental standards.

Raise community awareness: Propagate and educate people about the harmful effects of wastewater and proper waste disposal skills. Mobilize people to actively participate in protecting the environment, saving water, and changing littering behavior.

Completing the legal framework: Promulgate and strictly enforce legal regulations on wastewater management. Apply appropriate sanctions to deter illegal discharges that cause environmental pollution.

These are practical, comprehensive and sustainable solutions for wastewater treatment. The cooperation of the government, businesses and people is needed to implement these solutions effectively.

The best wastewater treatment chemicals today

On the market today there are many substances used to treat wastewater. Among them, the most effective are PAC, NaOH and Chlorine. Each type will have different characteristics and applications.

1. PAC sedimentation aid chemicals

PAC wastewater treatment chemicals appear commonly in most businesses, wastewater treatment systems, and water supply systems nationwide. PAC is produced in white powder form, easily soluble in water and has high hygroscopicity. Besides, PAC chemicals have the ability to coagulate organic compounds and heavy metals in water and remove them as quickly as possible.

2. Liquid caustic soda and NaOH flakes

Liquid caustic soda and caustic soda flakes belong to the Ph-neutralizing group, commonly used in industrial wastewater treatment. In solid form, NaOH is white, in pellets, granules or flakes. In solution form it exists in concentrations of 32% – 50%. NaOH is very hydrophilic, reacts violently with other substances and is easily absorbed by CO2 gas.

3. Chlorine chemicals

Chlorine is used in water treatment to disinfect and kill bacteria, disease-causing microorganisms or pollutants in wastewater. The product is manufactured with 70% content, meeting all needs from wastewater treatment to water supply and domestic water treatment. Chlorine is also used to disinfect tools and equipment in industrial factories.

Currently, wastewater treatment chemicals are being produced and widely distributed on the market by Dong A Chemical. Our products are guaranteed to be genuine, have the right content, and serve all needs of businesses in the manufacturing sector. We own a spacious workshop, a team of highly specialized staff, working continuously day and night to ensure the production of enough chemicals to serve nationwide. If you have any needs, please contact 0822 525 525 to be sent the latest price list.

PAC Dong A sedimentation aid chemicals

Frequently asked questions about wastewater

1. How is wastewater treated?

The wastewater treatment process is carried out according to the following steps:

Step 1: Preliminary treatment (mechanical): Remove trash, rough substances, sand, and grease.

Step 2: Biological treatment: Using microorganisms to decompose organic matter.

Step 3: Physical and chemical treatment: Use chemicals to thoroughly treat pollutants.

Step 4: Disinfection: Eliminate disease-causing microorganisms.

Step 5: Sludge treatment: Dry and bury the sludge safely.

2. What can each person do to limit wastewater?

Each individual can contribute to protecting the environment by:

Save water, do not litter indiscriminately.

Use environmentally friendly and degradable items.

Reuse water safely, raise awareness of water source protection

3. What is the difference between clean water and wastewater?

Clean water: Water is clean, safe, unused and does not contain pollutants.

Wastewater: Water that has been polluted by human activities needs to be treated before being discharged into the environment.

4. Which agency is responsible for wastewater treatment?

For domestic wastewater: City and local water supply and drainage units.

For industrial wastewater: Enterprises must build their own wastewater treatment systems and are responsible for wastewater quality.

5. Legal regulations on wastewater discharge

The Law on Environmental Protection 2020 stipulates that organizations and individuals discharging wastewater into the environment must be treated to national technical standards before discharge.

Decree 155/2016/ND-CP regulates sanctions for administrative violations in the field of environmental protection. Accordingly, the act of discharging wastewater in excess of allowed standards will result in a fine of 50 million – 1 billion VND.

Wastewater regulations: National technical regulations on domestic wastewater – QCVN 14:2008/BTNMT. National technical regulation on industrial wastewater – QCVN 40:2011/BTNMT.

Through this article, we hope you have a better understanding of what wastewater is, its origin, composition and impacts. It is the small actions of each of us that will contribute to reducing wastewater and protecting the environment.

Nguyễn Lân Dũng

Giáo sưNguyễn Lân Dũnglà nhà khoa học hàng đầu Việt Nam trong lĩnh vực vi sinh vật học (wiki), với hơn nửa thế kỷ cống hiến cho giáo dục và nghiên cứu. Ông là con trai Nhà giáo Nhân dân Nguyễn Lân, thuộc gia đình nổi tiếng hiếu học. Giáo sư giữ nhiều vai trò quan trọng như Chủ tịch Hội các ngành Sinh học Việt Nam, Đại biểu Quốc hội và đã được phong tặng danh hiệu Nhà giáo Nhân dân năm 2010.