Determination of BOD of water

Determination of BOD of water

Aim

To determine the dissolved oxygen concentration and biological oxygen demand of pond water

Principle

Dissolved oxygen of water is of paramount importance to all living organisms and is considered to be a factor which to a greater extent can reveal the nature of the whole aquatic system at a glance.  Dissolved oxygen is used as an indicator of the health of a water body.  Higher dissolved oxygen concentrations are correlated with high productivity and little pollution.  The presence of DO in water is mainly due to Direct diffusion from air and by Photosynthetic evolution by aquatic autotrophs.

The first one is purely a physical process and depends on the solubility of oxygen under the influence of temperature, salinity, water movement, whereas the later is a biological process and depends on the availability of light and rate of metabolic processes resulting in diurnal fluctuations.

Two methods are commonly used to determine DO concentration: The iodometric method which is a titration-based method and The membrane electrode procedure.  In the Iodometric method, divalent manganese solution is added to water, followed by addition of strong alkali in a glass-stopper bottle. DO rapidly oxidize an equivalent amount of the dispersed divalent manganese hydroxide precipitates to hydroxides of higher valence states. In acidic conditions, in the presence of iodide ions, the oxidized manganese reverts to the divalent state and iodine equivalent of the original DO content get liberated. The iodine is then titrated with a stranded solution of thiosulfate and the titration end point can be detected using a starch indicator.  Winkler Method uses titration to determine dissolved oxygen in the water sample. 

Biochemical oxygen demand (BOD) is the amount of dissolved oxygen needed or demanded by aerobic organisms to break down organic material present in a given sample at certain temperature over a specific time period.  It is a good index of organic pollution.  If the amount of organic matter in a sewage is more, then more oxygen will be utilised by bacteria to degrade it.  

BOD is calculated by keeping a sample of water containing a known amount of dissolved oxygen for five days in dark under aerobic conditions at 20^OC.   The oxygen content is measured again and BOD calculated.  Since nitrification consumes oxygen significantly, it will result in over estimation of BOD and must be checked by adding 1 ml of 0.5% solution of Allyl thourea.  In the water Samples where more than 70% of initial oxygen is consumed, it is necessary to aerate/oxygenate/dilute the sample with BOD free water to avoid oxygen stress.

BOD level in mg/litre                        Quality of water

            1 - 2                                         - Very Good

            3 - 5                                         - Fair

            6-9                                           - Poor

            100 or more                             - Very Poor

Reagents required

·         Manganese Sulphate solution - 48 g MnSO4.4H2O or 40 g MnSO4.2H2O or 36,4 g MnSO4.H2O in 100 ml distilled water

·         Alkali - iodide – azide reagent

o   Solution A - 500 mg NaOH and 135 g Sosium Iodide in 1 litre distilled water

o   Solution B - 10 g Sodium Azide in 40 ml distilled water

o   Solution A and B are mixed to get alkali -iodide - azide solution

·         Concentrated sulphuric acid

·         0.025 N Sodium Thiosulphate solution

·         Starch Solution - 2 g soluble starch in 100 ml distilled water.

·         Allyl Thio Urea Solution (0.05%)

·         Sulphuric acid (1N) - 2.8 ml of concentrated H2SO4 added to 100 ml distilled water

·         Sodium hydroxide (1 N) - 4 g of NaOH in 100 ml distilled water

Materials required

Water Sample, Pipette, Titration assembly, BOD bottle, BOD Incubator, Flasks, etc

Procedure

• pH of water sample was adjusted to neutral using 1N acid or 1 N alkali Solution.
• The pond water sample was filled in 2 BOD bottles without any bubble formation.
• 1 ml alkyl thiourea was added to 1 bottle.
• 2 ml of manganese sulphate was added slowly to the bottle by inserting pipette below the surface of water so that no air bubbles are introduced via the pipette.
• 2 ml of alkali - iodide - azide reagent was added in the same manner.  The bottle was stoppered with care so as not to allow air entry in to the bottle and mixed the sample by inverting several times.  If oxygen is present, a brownish - orange colour of precipitate or floc will appear.  
• The precipitates formed are dissolved by adding 2 ml of concentrated sulphuric acid by keeping the pipette very near to sample surface.  Again after carefully stoppering, the bottle was inverted several times to dissolve the floc.  
• 50 ml of the sample from the bottle was titrated with 0.025 N sodium thiosulphate, till a pale straw colour is formed.
• 2 ml of starch solution was added, and a blue colour formed
• Titration is continued until the sample colour turns clear.
• The burette reading was noted.

·         Calculation of D.O. in mg/Liter = 8 X 100 X N/V X v

§  V = Volume of sample taken 

§  v = Volume of 0.025N Sodium thiosulphate solution used 

§  N = Normality of titrant = 0.025

§  8 is constant (1ml of 0.025N Sodium thiosulphate solution is equivalent to 0.2mg oxygen).

• The concentration of dissolved oxygen in the sample is equivalnet to the volume of 0.025 N sodium thiosulphate used.   Each ml of 0.025 N sodium thiosulphate added is equal to 1 mg/L Dissolved oxygen. This is recorded as Dissolved Oxygen (D1).  
• The other 2 bottles are kept in BOD incubator at 20^OC and after 5 days, the dissolved oxygen was determined by the above method and the value was recorded as Dissolved Oxygen (D2).
• The BOD of water in mg/Liter was calculated as BOD = D1-D2
• D1 is the initial dissolved oxygen concentration of the sample before 5 days incubation and D2 is the concentration after 5 days of incubation.

 

 

 

 

 

Trade Marks, Well-known marks and Domain Names

Definition of trademark

A trademark is a type of intellectual property consisting of a recognizable sign, design, or expression which identifies products or services of a particular source from those of others.  Trademarks used to identify services are usually called service marks.  Trademarks may protect signs, in particular: words, letters, numerals, abbreviations, graphical representations, combinations of colors and the tints thereof, three-dimensional forms, shapes of the goods or the packaging, provided that they are distinctive, as well as the combinations of all the above indicated signs.  A seal, a stamp and a hallmark shall not be considered to be trademarks.

Functions of a Trademark

A trademark serves the purpose of identifying the source or the origin of goods. Trademark performs the following four functions.

·  It identifies the product and it’s origin.

·  It guarantee its quality.

·  It advertises the product. The trademark represents the product.

· It creates an image of the product in the minds of the public particularly the consumers or the prospective consumers of such goods.

How is a trademark protected?

Trademarks are protected by intellectual property rights.  At the national/regional level, trademark protection can be obtained through registration, by filing an application for registration with the national/regional trademark office and paying the required fees.

How is a trademark registered?

At the national/regional level, trademark protection can be obtained through registration, by filing an application for registration with the national/regional trademark office and paying the required fees. At the international level, there are two options: either we can file a trademark application with the trademark office of each country in which you are seeking protection, or you can use WIPO’s Madrid System.

The application must contain a clear reproduction of the sign filed for registration, including any colors, forms, or three-dimensional features. The application must also contain a list of goods or services to which the sign would apply.  The sign must fulfill certain conditions in order to be protected as a trademark or other type of mark. It must be distinctive, so that consumers can distinguish it as identifying a particular product. It must neither mislead nor deceive customers or violate public order or morality. The rights applied for cannot be the same as, or similar to, rights already granted to another trademark owner. This may be determined through search and examination by the national office, or by the opposition of third parties who claim similar or identical rights.

How long is a registered trademark protected for?

The term of trademark registration vary, but is usually ten years. It can be renewed indefinitely on payment of additional fees. Trademark rights are private rights and protection is enforced through court orders.

How extensive is trademark protection?

Almost all countries in the world register and protect trademarks. Each national or regional office maintains a Register of Trademarks which contains full application information on all registrations and renewals, facilitating examination, search, and potential opposition by third parties. The effects of such a registration are limited to the country concerned.

In order to avoid the need to register separately with each national or regional office, WIPO administers a system of international registration of marks. This system is governed by two treaties, the Madrid Agreement Concerning the International Registration of Marks and the Madrid Protocol.

What are well-known marks and how are they protected?

The term 'well-known trademark' refers to a mark which has become so well-known to the substantial segment of the public through its extensive and continuous use. Use of the mark in relation to any other goods or services by another party may be taken as a connection between the two parties.

In India, there are specific provisions under the Trade Marks Act, 1999 and procedure to record well known trade marks in India is provided under the Trademarks Rules, 2017 enacted under the Act, 1999.

As per the Trade Marks Rules, 2017, an application is required to be filed (online) at the Trade Marks Registry supported by evidence of use. The Trade Marks Registry, Mumbai reviews the application filed to verify the filing requirements. Thereafter, hearing is appointed at Mumbai Trade Marks Registry to present the case. If the hearing officer is convinced that the trade mark should be declared as a well-known trade mark, the trade mark is advertised in the Trademarks Journal (TMJ) inviting objections from the general public within 30 days from the date of publication in the TMJ. If, no objections are received, the trade mark is advertised in the trade mark is advertised in the TMJ and included in the list of well-known marks.

Examples are Whirlpool, ENFIELD BULLET, HONDA, HORLICKS, Infosys, etc.

Domain name

A domain name is an identification string that defines a realm of administrative autonomy, authority or control within the Internet. Domain names are used in various networking contexts and for application-specific naming and addressing purposes.  A trademark or service mark promotes and protects the brand name, while a registered and protected domain name provides protection against any unauthorized use of domain name by any person or entity.  Often a business will use its business name, brand name or another business identifier as its domain name.

Unlike trade marks, domain names are:

·         global

·         unique by nature

·         can't be shared between two websites

Registering a domain name doesn't automatically give us any rights over the matching trade mark. Trade mark right can be obtained only by registering the domain name as a trade mark.

	Domain name	Trade mark
Definition	A domain name is a unique string of letters that is a part of an internet address. It is common for a domain name to be the same or similar to a trade mark or a business name.	A trade mark is any sign which can tell apart your goods and services from those of your competitors.
Uses	Domain names are used to locate and bring users to a specific website or place on the internet.	A trade mark is used to identify and distinguish your goods or services in the marketplace.
Need to Register	Yes. Can submit a registration to any ICANN-accredited registrar. Registering a domain name gives you exclusive rights to use that domain for the duration of the license period.	No, but it in most cases it would be wise to do so. You can protect a registered trade mark by law.
Do it expire?	Yes. And can renew indefinitely (subject to paying renewal fees on time).	Yes. Generally after ten years, after which we can renew the trade mark registration.

 

Sulfur Cycle and Phosphorous Cycle

Sulfur cycle

Sulfur cycle is the circulation of sulfur in various forms through nature. Sulfur occurs in all living matter as a component of certain amino acids. The sulfur reservoir is in the soil and sediments where it is locked in organic (coal, oil and peat) and inorganic deposits (pyrite rock and sulfur rock) in the form of Sulphate, sulphides and organic sulfur.  It is released by weathering of rocks, erosional runoff and decomposition of organic matter and is carried to terrestrial and aquatic ecosystems.  The sulfur cycle is mostly sedimentary except two of its compounds, hydrogen sulphide (H2S) and sulfur dioxide (SO₂), which are gaseous components. 

Sulfur is present in three forms in the biosphere, Elemental Sulphur, Inorganic Sulphur (sulphate in aerobic soil and as sulphide in anaerobic soil) and Organic Sulphur (amino acids and plants/animal residues).  Sulfur is an essential part of all living matter because sulfur containing amino acids are always present in almost all kinds of proteins.

Sulfur cycle in brief, Sulfur-containing proteins are degraded into their constituent amino acids by the action of a variety of soil organisms. The sulfur of the amino acids is converted to hydrogen sulfide (H2S) by another series of soil microbes. In the presence of oxygen, H2S is converted to sulfur and then to sulfate by sulfur bacteria. Eventually the sulfate becomes H2S.  Hydrogen sulfide rapidly oxidizes to gases that dissolve in water to form sulfurous and sulfuric acids. These compounds contribute in large part to the “acid rain” that can kill sensitive aquatic organisms and damage marble monuments and stone buildings.

Different processes involved in Sulfur Cycle

 

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Sulfur disproportionation is an ecologically and technologically important part of the sulfur cycle. It is also termed dismutation or “inorganic fermentation” as one sulfur compound serves as electron donor and acceptor.

Assimilatory sulfate reduction – algae and many heterotrophic microorganisms assimilate sulfur in the form of sulfate.  Since direct uptake as sulfide is not feasible due to high toxicity of H2S, the reduced sulfur is immediately reacted with an acceptor, serine to form cysteine. 

Organosulfur decomposition or desulfuration of organic compounds in soils and sediments yield mercaptans and H2S. 

1.  Degradation of proteins through proteolysis liberates amino acids containing sulfur

2.  Heterotrophic bacteria use sulfur containing amino acids and release H2S.  For example, cysteine desulphurase enzyme will convert cysteine to pyruvic acid and H2S and NH3

3.  Some bacteria such as Desulfotomaculum can reduce sulphates to H2S.

In marine environments, the major decomposition product of organosulfur is DMS or dimethyl sulfide which is formed from dimethylsulfoniopropionate (DMSP), which is used by bacterioplankton (floating bacteria) as a sulfur source for protein synthesis and H2S. DMS, Mercaptans and H2S escape to atmosphere and upon photo oxidations become sulfate. 

Oxidative sulfur transformations

The H2S may get subjected to microbial oxidation under aerobic conditions or phototrophically oxidized under anaerobic conditions.

Chemolithotrophic microbes such as Beggiatoa, Thioploca, Thiothrix, etc oxidises H2S to Sulfur.  Sulfur globules are deposited in the cells.  In the absence of H2S, these globules are slowly oxidized further to sulfate.  

Some species of Thiobacillus oxidise H2S and other reduced sulfur compounds and deposit elemental sulfur since they are not highly acid tolerant.  Some other members of Thiobacillus produce sulfuric acid from the oxidation of elemental sulfur and other sulfur compounds under aerobic conditions.  Thiobacillus denitrificans carry out sulfur oxidation under anaerobic conditions utilizing nitrate as terminal electron acceptor.

H2S is also phototrophically oxidized under anaerobic conditions by photosynthetic sulfur bacteria (Chromatiaceae, Chlorobiaceae, Ectothiorhodospiraceae, etc).  Chromatiaceae store sulfur globules intracellularly, Chlorobiacea and Ectothiorhodospiraceae excrete sulfur globules.  Some cyanobacteria also participate in the phototrophic oxidation of H2S.

Reductive sulfur transformations

Sulfite can be reduced to sulfide by a wide variety of microorganisms, including Alteromonas, Clostridium, Desulfovibrio and Desulfotomaculum.

Desulfuromonas acetoxidans grow using acetate under anaerobic conditions by reducing sulfur to H2S. 

Extremely thermophilic anaerobic archaea such as Thermoproteus, Pyrobaculum, Pyrodictium, etc are capable of sulfur respiration with hydrogen gas.

H2 + S ---> H2S

Some species of Bacillus, Pseudomonas and Sacharomyces is also capable of releasing H2S from sulfate.

Some obligately anaerobic bacteria carry out dissimilatory sulfate reduction and they are known as sulfate reducers or sufidogens.  Examples are Sulfate reducing bacteria such as Desulfovibrio, Desulfotomaculum, etc reduce sulfate to H2S.

The production of H2S have a marked effect on the population in a habitat.  H2S is highly toxic to aerobic organisms since it reacts with heavy metal groups on cytochromes.  It kills nematodes and other animal populations in water logged soils and destroys plant roots and can kill plants. H2S also have antimicrobial activity.

 

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Phosphorous Cycle

The phosphorus cycle is the biogeochemical cycle that describes the movement of phosphorus through the lithosphere, hydrosphere, and biosphere.  Phosphorous Cycle is a sedimentary biogeochemical cycle. Phosphorous reservoir is mostly in the form of rock deposits and is not present in gaseous form in the biosphere. Phosphorous is one of the key element of the biosphere. It is an essential component of the cell in DNA, RNA, ATP and phospholipids.  Phosphorous is present in the environment as phosphates of Calcium and Iron which are usually insoluble. 

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The dead remains of the flora and fauna including microbes act as the source of phosphorous in the soil environment. Phosphate can serve as terminal electron acceptor in the absence of sulfate, nitrate and oxygen.  The final product of phosphate reduction is Phosphine (PH₃).  Phosphine is a volatile and toxic gas and ignite in presence of oxygen and produce green glow. This is liberated from swamps, soils, and marine regions where there is extensive decomposition and ignites when exposed to air and can ignite methane and give rise to ghostly light phenomena. 

Phosphate which enters the aquatic ecosystem becomes part of the marine sediment.

The microbial transformation of phosphorus involves primarily the transformation of phosphorus from simple orthophosphate to various more complex forms, including polyphosphates found in metachromatic granules.

The phosphorus cycle has two main steps

Mineralization: Conversion of Organic Phosphorus into Insoluble Inorganic Phosphates

Solubilization: Conversion of Insoluble Inorganic Phosphates into Soluble Inorganic Phosphates

Both these processes are operated by the soil microbial population.

Mineralisation occurs with the help of enzymes phosphatases.  Phosphorous mineralization is mainly carried out by the microbial population.   Many soil microorganisms produce enzymes that attack many of the organic phosphorus compounds in the soil and release inorganic phosphate.  Organic phosphorous reach soil from dead remains of plants and animals and also from animals excretions such as urine and faecal matter.  Some bacteria and fungi produce phytase which releases soluble inorganic phosphates from inositol hexaphosphate or phytic acid.

Solubilization - Bacterial population such as Bacillus, Micrococcus, Pseudomonas and fungi such as Aspergillus, Penicillium and Mycorrhiza are involved in the solubilisation of phosphorous.  Presence of Phosphate solubilizing microbial population increases the phosphate assimilation in plants. The mechanism of phosphate Solubilization is mainly by production of organic acids.  Nitrosomonas and Thiobacillus produce nitrous and sulfuric acids respectively and solubilize inorganic phosphates.  Phosphorous Solubilization is affected by a number of factors such as temperature, pH, aeration, carbon and nitrogen source etc.  In marine environment the availability of Phosphorous depends on the temperature of the surface water. Here the dissolved Phosphorous gets incorporated in the phytoplanktons.  

Microbial activities may also immobilize phosphorous.  Thus it become unavailable to biological community.  The assimilation of phosphorous into cell constituents such as membranes remove phosphate from available pool.  The Phosphorous present in sediments deep in ocean also is not biologically available.  When phosphorus-containing compounds from marine organisms sink to the floor of the ocean, they form new sedimentary layers. Over long periods of time, these sedimentary rock may be moved from the ocean to the land by a geological process called uplift, this is a very slow process.

Phosphate concentration highly influences primary productivity.  Addition of phosphates from detergents into lakes makes the lakes eutrophic, there will be algal and cyanobacterial blooms, increased organic matter in the water body and subsequent decomposition of the organic matter deplete the water body of oxygen which result in fish kills.