Resume Abstract

Abstract

Соntent

• Introduction
• 1. Characteristics of water
• 2. A method of cleaning phenol‑containing waste
• 3. Сoagulation and flocculation
• 4. Laboratory eksperiment
• Conclusion
• References

Introduction

Wastewater treatment — one of the most important problems of the chemical industry.

The principal objective of wastewater treatment is generally to allow human and industrial effluents to be deleted without danger to human health or unacceptable damage to the natural environment.

Various chemical and industrial processes produce phenol-containing wastes which are toxic to the environment and from which the phenols must be moved prior to disposal.

Wastewater from a chemical industry usually contains hazardous chemicals, as hydrocarbons, phenols and ammoniacal nitrogen among others.

Biological treatment is a more natural wastewater treatment process than other wastewater treatment methods. Microorganisms feed on the complex materials presented in the wastewater and turn them into simpler substances, preparing the water for the further treatment.

1. Characteristics of water

Wastewater containing phenol is generated in many steel industry’s coking facilities. A typical phenol concentration in the effluent water is 6.8 wt%. Before releasing this water to the environment, the phenol concentration must be reduced to 39 ppb.

This abstract provides details on the latest developments and efforts in the removal of phenol from wastewater.

2. A method of cleaning phenol-containing waste

To minimize these problems, the suspended particles are typically removed or reduced to an acceptable level prior to use and discharge.

Large particles can be easily removed mechanically by filtration or settling. Finer particles, also known as colloidal particles, are harder to filter or settle out.

All natural water contains suspended particles that can be detrimental to the water’s intended use and application. Problems can range from poor product quality, to high maintenance and operating costs, to premature equipment failure.

As the water is used in further processes, such as in heating, cooling, cleaning, it picks up more particles along the way, which eventually become pollutants in wastewater discharge.

Mechanical ways of cleaning assume the use of filtering, upholding and filtering of industrial sewage.

A method of cleaning phenol-containing waste waters as derived from coke-producing, chemical and other industrial processes comprises treating the waste water, generally without any preconcentration of the phenol content thereof or other prior treatment, with a one-use adsorbent, namely, brown-coal coke.

Cleaning in airtanks the sewage clarified in primary sediment bowls is carried out by the slow admission through them of the sewage enriched with oxygen, and their mixing with active silt. Active silt represents itself the community of microorganisms and small invertebrate animals (a mold, yeast, water mushrooms, etc.) and also a firm substratum.

3. Сoagulation and flocculation

The terms of coagulation and flocculation are often used interchangeably. Although both will agglomerate the colloidal particles, they accomplish this in different ways:

Coagulation neutralizes the charges on the particles to remove the repulsion forces between particles, allowing them to come closer, and to agglomerate.

Flocculation bridges the particles to make them even bigger so they can be removed effectively and efficiently.

Most popular coagulants are aluminum and ferric salts.

After coagulation, the pin flocs are usually still too small to settle or filter efficiently. A flocculant is added to help bridge the pin flocs to form larger flocs, improving their filterability or settling rate.

Flocculants have considerable molecular weight and have long molecular chains. One might think of the flocculant as the octopus tentacles with several suction cups to grab onto the agglomerated pin flocs. Flocculants can be anionic, cationic or non-ionic and come in powder or emulsion form. In either form, the flocculant must be diluted down to about 0.5 percent before using.

Coagulants and flocculants have some overlapping capabilities. Aside from bridging, charged flocculants (anionic or cationic) can also neutralize charges on the colloidal particles. However, coagulants are still more effective because they have higher charge density.

Because of these overlapping capabilities, the terms coagulants and flocculants are often used interchangeably. As for pH, most coagulants and flocculants will work well within the pH of 4 to 10. However, every application has its own optimum pH level, so it is beneficial to test the performance of the coagulants and flocculants against varying pH conditions and adjust the pH of the solution to meet that optimum level.

4. Laboratory eksperiment

Optimal reagents:

• quicklime;
• iron sulfate;
• polyacrylamide.

Application technology of coagulation and flocculation consists of 3 stages:

• dosage and mixing of quicklime with water to pH = 7.2 — 7.5;
• coagulant mixing with water;
• polyacrylamide mixing with water;
• water settling of suspended particles.

With a microscope we compared the water after treatment and the initial water with different coagulants. The results are shown in Figure 1.

The results of chemical and microbiological tests showed that better wastewater coke production is achieved using Al₂(SO₄)₃

Conclusion

Main characteristics of wastewater and possible methods of wastewater treatment were substantiated.

Biological treatment is a more natural wastewater treatment process than other wastewater treatment methods.

Thus it is very important to pick up temperature correctly, the reaction of environment, stimulating additives, careful hashing and an effective oxidizer that in the maximum degree to promote an intensification of the hydrobiocenosis which is making an active silt, absorbing pollution. The given method is rather effective and is applied only to additional cleaning of sewage as high concentration of components-pollutants perniciously influence on microorganisms which live in active silt.

Physicochemical sewage treatment is carried out basically with application of such methods, as coagulation, flotation and sorption.

The goal of the work is to reach substantially complete precipitation of active sludge in water.

The concentration of major pollutants decreased significantly, the water has improved its color and smell.

This master's work is not completed yet. Final completion: December 2013. The full text of the work and materials on the topic can be obtained from the author or his head after this date.

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