Faculty of Engeneering Science

Faculty of Engeneering Science

Subject:Secondary wastewater treatmentBiological Methods

Professor: Sandra Stefanovic Student: Visnjic Katarina 920/2014

Kragujevac, December 2014

Contents1. Fundamentals of biological processes21.1 The cellular metabolism and bioreactors21.2. The parameters that influence biological processes.32. AEROBIC BIOLOGICAL PROCESSES42.1. Providing aerobic process oxygen52.2. Activated sludge62.2.1. The composition of the microflora of activated sludge72.2.2. The main technological parameters82.3. Aerobic aerated lagoons and lakes aerobic83.ANAEROBIC BIOLOGICAL PROCESSES93.1. The necessary technological conditions of fermentation anaerobic10Literature:11

1. Fundamentals of biological processes1.1 The cellular metabolism and bioreactors

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Biological Methods for purification of water based on the metabolic activity of a large number of microorganisms, which are biodegradable pollution, is used as a source of mineral elements for the growth and reproduction, and as a source of energy to support these processes.

Cellular metabolism is the sum of a large number of enzyme-catalyzed reactions that are divided into two groups:

1. The process of catabolism, in which the substances are entered from outside of the cell and broken into more simple, with the release of chemically bound energy.2. The process of anabolism, which synthesizes a substance required for building the biomass.

Environmental factors (ecological factors) are the main conditions for realization of all the chemical and biochemical processes. These conditions significantly affect the metabolism of microbial cells.When microorganisms are used in processes for wastewater treatment, these factors are referred as process parameters.

Metabolism is very complex and made of a large number of interdependent and interconnected biochemical reactions, and each of them catalyzes a specific enzyme. Because of that, we can not control it as a chemical reaction out of life function.The product of metabolism is the new living cell, which is a very complex chemical composition.

BIOREACTORS

All industrial biological processes for the purification of liquid waste and solid waste are based on the natural processes of self-purification. Due to constant natural changes, the conditions are not optimal and so the processes are slow-going.In order to optimize the conditions, the specific vessels named bioreactors were built. They are in charge for doing optimization of conditions and control and process management.

1.2. The parameters that influence biological processes.

The course for biological processes of liquid waste is affected by all those parameters which influence the microbial activity.The most important are:

- Type and concentration of nutrients- Concentration of oxygen- Water activity- Temperature- pH- The presence of toxins- The rheological character of environment

2. AEROBIC BIOLOGICAL PROCESSES

They occur according to the following reaction:

C6H12O6 + + 6H2O 6O26CO2

Very important to mention for aerobic processes is that they are large consumers of energy, which is needed to ensure the required oxygen.If the level of pollution increases, require for oxygen raises.Aerobic biological processes, from the aspect of liquid waste treatment, are conducted according to the following scheme:

org. supstancie CO2 + H2O + Q + A NEW MICROORGANISMS

This reaction occurs in the presence of aerobic microorganisms[footnoteRef:2]. [2: Aerobic microorganisms - live only in the presence of oxygen ]

2.1. Providing aerobic process oxygen

The purpose of providing aerobic conditions is that the oxygen concentration drops below 0.3 mg/l and tends to be at the level of 0.8 mg 02/l.In this case there are reserves that prevent oxygen of entering the system in aerobic condition.Two processes are used: Aeration Oxygenation.

* Aeration is the process of oxygen placement in the water from the air, in which oxygen is present in the amount of around 21%.It is used in biological processes in which large capacities are needed. Two of those are:

** Oxidation is a process of oxygen transfer in the water from the gas environment, which consists of oxygen or a mixture of oxygen and air in various proportions.

2.2. Activated sludge

Activated sludge is the name of the biologically active biomass of aerobic micro flora, which is suspended in the liquid waste in the form of flocks. The flocks consist of a living and active micro-organisms, dead cells as well as the organic (biodegradable and non-biodegradable) and non-organic substances from the liquid waste, which is about to be purified. Liquid waste is placed into the reactor, in which the activated sludge is maintained in suspension. Through aerobic micro flora of the activated sludge biological oxidation of organic liquid waste pollution is made. The reaction of dissimulation and biological oxidation are happening practically simultaneously, oxidation of organic matter.The selection of the equipment for purification of waste water based on activated sludge for settlement Boksiand aptinovci in the municipality urenovac, the advantages and disadvantages of the purification device.As set out in that remote and smaller communities of 500 to 2000 ES suitable equipment In particular, based on the activesludge, for better purification, which is important when it comes to water protection sections. disclosed areParts and operation of the equipment for waste water purification based on active sludge.

2.2.1. The composition of the microflora of activated sludge

The most important and the most frequent and activated sludge microorganisms are bacteria. Basically, those are gram-negative bacteria.Other types of micro-organisms have an important role in the purification of activated sludge such as protozoa, which feed dispersed (uninoculated) and nilifere bacteria that remove small, non-precipitated activated sludge flocks, play a significant role in the final purification, the so-called. polishing, aerobic reactor effluent

2.2.2. The main technological parameters

The main technological parameters of activated sludge treatment are: Load of the process, SAR degradation (consumption) of the pollution, and Approximate retain time of microorganisms (or sludge age).The process of purification of activated sludge is controlled by the amount of sludge taken from the system (which depends on the concentration of sludge in the reactor) and the approximate time to keep the micro-flora in the system. The amount of sludge removed from a system must be less than the net population growth of micro-flora, in order to sustain micro-flora non-rinsed, i.e. to sustain concentration of activated sludge in the reactor.

2.3. Aerobic aerated lagoons and lakes aerobic

This is a technique in everyday life a lot of sense because scientific approaching method real-natural decay bacteria. In simple words, it panders only under treatment. These are the open earthen basins, resulting from various ways. In Backa pools are usually formed by digging the earth for brickworks.In some other parts of Serbia are usually abandoned mines, etc . We can say to disposal of sewage sludge from the procedure of processing and storage posts safeguarding actually produce biological reactors. In these ravines, excavation, mining, carried out aerobically treating OJ. Advantageously, and so is that place away from the settlement (Planned away Kac) because of domestic animals and unpleasant odors Artificial dug gullies, lakes and lagaune TRAINING are well placed when compared to those settlements, rectangular square in shape, and with the possibility of traffic approaches. Special conditions apply to the mining pits that are inaccessible.

Procedures of aerobic biological treatment with suspended micro-flora, which are similar to the natural self-purification processes, are aerobic aerated lagoons and (especially) aerobic lake. Those are built as large pools (natural or artificial), which serves as biological reactors, in which liquid waste is being purified in aerobic way. These procedures are used when we have sufficient of available land area and when the intense of the odor emission (created in aeration process on the large water surface) can be tolerated (usually in the case of sufficient distance from residential areas). Artificial, dug lagoons or lakes are usually rectangular or square shape, while the natural lagoons have irregular shape or just follow the configuration of the field.

3.ANAEROBIC BIOLOGICAL PROCESSES

Application of the anaerobic digestion of wastewater treatment and sludge is widespread throughout the world. By definition, the anaerobic digestion is the use of microorganisms in the absence of oxygen for the stabilization of organic materials to methane gas, and converting the inorganic products, including carbon dioxide.This process is used for the treatment of wastewater from industrial, agricultural and cities. Industrial waste water originating from:

- Brewers,- Dairy,- Food production,- Chemical industry,- The pharmaceutical industry

Agricultural waste water can be originating from farm pigs, cattle, chickens and others. Typical solids content of the components in the digester low load is 3 to 10%, in highly loaded 10 to 30%. Reduction of COD varying between 75 and 90%.

3.1. The necessary technological conditions of fermentation anaerobic

The technological process of fermentation anaerobic conditioned by the existence and fulfilling the appropriate conditions - in order to achieve a result with a higher degree of decomposition of organic matter and satisfactory quality and yield of biogas.

Basic technological conditions for the anaerobic process of fermentation are:- Seed size and type of material,- The temperature during the process,- The pressure in the digester,- The value of pH,- Quality of methane bacteria,- Bezkiseonina atmosphere digester,- The retention time of the digested substrate,- The ratio of carbon and nitrogen in the substrate (C / N),- Mixing of the substrate in the digester,- The ratio of the dry organic substance and water in the substrate.

Each of these conditions has a certain degree of influence on the flow of the process of anaerobic fermentation. To ensure that these conditions could provide, it is necessary to know their nature and magnitude of the process of anaerobic fermentation. For this reason it is necessary for each of the conditions to know the basic facts.

Literature:

1. Classbook for IV years of high school2. Josip Baras, Processing and disposal of liquid waste, Department of textbooks Belgrade3. www.wikipedia.com4. The book of organic chemistry