Selection and justification of technology of purification of sewage
PJSC Donetsk city Dairy Plant No. 2

Content

• Introduction
• 1 Actuality of theme
• 2 Purpose and research tasks, planned results
• 3 Evaluation of the company influence on the state of the hydrosphere
• 4 Technological solution for cleaning of industrial waste water
• 5 Rational use of sediment formed during wastewater treatment
• Conclusions
• The list of sources

Introduction

The problem of environmental protection and rational use of water resources is one of the most important environmental problems. The principle of rational nature provides for the minimization of fresh water consumption for technological needs through high-efficiency wastewater treatment.

In the city of Donetsk, one of the leading dairies is PJSC Donetsk city Dairy Plant No. 2, which belongs to the enterprises of V class of danger. The size of sanitary-protective zone of the plant is 50 meters.

On a production site of PJSC Donetsk city Dairy Plant No. 2 there are 16 stationary sources of emissions of polluting substances in atmospheric air, 7 among which are organized (including 1 — reserved); 9   unorganized [1].

Donetsk city Dairy Plant No. 2 has the international certificate of management system of food safety according to ISO 22000:2005 (requirements for the organization of the whole of the food chain) and the international management system certificate according to ISO 9001:2008.

1 Actuality of theme

Relevance of the work lies in the fact that the company, being in the environmentally safe area in the southwestern part of the city of Donetsk, is a source of environmental pollution. Therefore, the quality of discharged waste water and emissions into the air of the enterprise, as well as recommendations for its reduction are very important from the point of view of security of this region and the region as a whole.

2 Purpose and research tasks, planned results

The purpose of this masters thesis is to assess the impact of PJSC Donetsk city Dairy Plant No. 2 on the environment in close proximity to businesses, the impact of discharged wastewater and the development of measures to reduce it.

To achieve this goal the following tasks were set:

1. to assess the general nature of the company influence on the natural environment of the city of Donetsk;
2. to analyze the discharge of sewage of the enterprise;
3. to Investigate in the laboratory the samples of waste water;
4. to assess water quality;
5. review and analyze existing cleaning methods;
6. to Develop a scheme of the treatment plant to improve the quality of discharged wastewater.

Object of research: waste water of PJSC Donetsk city Dairy Plant No. 2.

Subject of research: development of measures for the treatment of waste water PJSC Donetsk city Dairy Plant No. 2.

3 Assessment of impact of enterprises on the state of the hydrosphere

PJSC Donetsk city Dairy Plant No. 2 refers to water-intensive companies that consume significant amounts of water. The source of water supply enterprises are analyzed urban water supply network.

At PJSC Donetsk city Dairy Plant No. 2 of high demands on industrial hygiene, which entails frequent washing and disinfection of production equipment, inventory and premises, leads to the formation of polluted wastewater. Important indicators of sewage are the values of COD and BOD, pH, suspended solids (dry residue), total and ammonia nitrogen, hydrogen sulfide, phosphorus, surface-active substances (surfactants).

At PJSC Donetsk city Dairy Plant No. 2 there is a serious problem of wastewater disposal, as sewage treatment plants the company has.

In-plant waste water network sewage is collected in two issues of on-street Cyclone, near R. Bad, then combined on Leninsky Prospekt, where a test well No. 1, and sent by gravity to the city sewer No. 11 and then to the city sewage treatment plant.

At this stage of the masters work carried out 2 experiments. We studied samples of wastewater in the laboratory and determined the content of hydrogen sulfide and chemical oxygen demand (COD).

As a result of experiments, a volumetric method determined that the hydrogen sulfide content was 1.25 mg/dm³, while the maximum permitted concentration of pollutant 1 mg/dm³ and the content of COD is 381.7 mg/dm³, the maximum permissible concentration of pollutants is 350 mg/dm³. Thus, the discharge of waste water now exceeds the standards of pollutants in terms of hydrogen sulfide and COD.

4 Technological solution for cleaning of industrial waste water

Process Wastewater Treatment — is a complex multi-level and knowledge-based task that successfully and efficiently solved with the introduction of innovative technologies.

Wastewater PJSC Donetsk city Dairy Plant No. 2 should be subject to mechanical and biological treatment. Our proposed process flow diagram is shown in figure 1.

Gravity feeding offer industrial waste water in the buffer tank, which is designed for averaging the flow and provide uniform supply flow to clean. drains directed to flotation unit from the buffer tank.

Flotation plant, staffed with a drum sieve intended for the removal of waste and fat particles larger than 2 mm system microbubble flotation. Then, ensure the supply of wastewater gravity into the anaerobic pool.

Anaerobic gated pool serves as a selection of special bacteria, extracting excess phosphorus from wastewater. At the same time in the pool to direct part of insufficiently treated liquid from the aeration basin and a pump in the pool fed from a dispenser aluminum salts. To ensure the quality of incoming streams mixing pool equipped with two agitators.

With anaerobic liquid pool by gravity to guide anoksik pool, it also provides fluid flow from the anaerobic pool and 2 pools membrane aerobic post-treatment. To ensure the quality of incoming streams mixing pool equipped with two agitators. In anoksik air swimming pool is not supplied, to ensure that the bacteria use NO₃-N as an oxygen source. Liquid basin anoksik pumped via pumps preliminary aeration basin and then into membrane bioreactor system for further purification.

The pool preliminary aeration for biological wastewater treatment. In the pool from the blower to supply air to provide oxygen for the removal of COD and BOD of wastewater. Aeration and mixing are provided tonkopuzyrkovoy diffuser system complete with two blowers. From the aeration basin, partially stabilized waste water flows by gravity into the reactors equipped with membrane modules (MBR).

Membrane bioreactors — intended for biological wastewater treatment on the surface of the membrane and the separation of treated effluent from the biomass. The MBR basin there is a final separation of the liquid (treated effluent) and solid phase (activated sludge) [4]. Treated sewage filtered membranes, will be ready for final discharge. A mixture of liquid and activated sludge may partly come from the MBR overflow basins anoksik pool. Membranes provide more than eight orders of removal of bacteria and viruses 7 orders removal, so that disinfection requirements are met [5].

Treated effluent from the membrane is deflected by a pump with flow control the flow into the pond or city collector. For dewatering of activated sludge before transportation to the fields as fertilizer use centrifuge (decanter).

To prevent the possibility of emissions into the atmosphere to construct treatment facilities closed. Respiratory systems provide absorption filter system.

5 Rational use of sediment formed during wastewater treatment

Sludge formed after cleaning is used as fertilizer on agricultural fields.

Part of the mineral precipitation is represented mainly by the compounds of calcium, silicon, aluminum and iron. Activated sludge is the most valuable as organic fertilizer, especially rich in nitrogen and digestible phosphates. The content of these substances in sediments is determined by the composition of wastewater and the technology of its cleaning. The accumulation of potassium in the soil does not occur, as in precipitation is not enough of this element. Introduction precipitation reduces soil acidity and increases the content of nitrogen, humus and phosphorus [6].

Thickening of the activated sludge and its further thermal drying will make it possible to obtain a dry product for nutritional value close to the fodder yeast [7].

Along with the use of rainfall in farming practices, promising their use for feed additives and medicines for livestock feeding, birds, fish and animals of species [8].

When processing the raw precipitation and activated sludge can be used in the cement industry. Annual growth of activated sludge biomass is how millions of tons. Therefore there is a need for methods for recycling, which allow to expand the range of application of the activated sludge.

Conclnsions

As a result of the analysis of the impact of PJSC Donetsk city Dairy Plant No. 2 local treatment facilities that would significantly reduce the burden on urban collector suggested. Thus, the proposed implementation will allow the enterprise to increase the efficiency of its production, improve its position in relation to the natural environment, and to obtain economic benefits in the form of lower environmental costs.

When writing this abstract master's work is not yet complete. Term of final completion: may 2017. Full text works and materials on the topic can be obtained from author or his supervisor after the specified date.

The list of sources

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