Sludge in Wastewater - How it is Made Safe For Disposal

During sewage treatment, a thick residue is obtained, known as sludge. This is the primary sludge in wastewater. It gives off a strong and offensive odor. Sludge thus obtained can't be disposed of unless it is treated again. In this article, I discuss how this sludge can be treated and made safe for disposal.

Sludge settles at the bottom of the tank during the primary treatment process. This is called Primary Sludge. It gives off a strong and offensive odor. Secondary treatment, to dispose off sludge, is done by making use of the microorganisms left in the sludge, in wastewater, after the primary treatment. Hence the Secondary Sludge thus obtained is rich in microorganisms. The sludge in wastewater is then treated with an aim to stabilize the sludge contents. This causes a reduction in odor. This treatment is also aimed at reducing the volume of the sludge. This is achieved by reducing the water content of the sludge. Further reduction in volume is achieved by encouraging the microorganisms to breakdown the organic matter present in the sludge. The next step in the treatment of the sludge is to disinfect the sludge. This is accomplished by killing the pathogenic microorganisms left in the sludge.




Almost 97 percent of the sludge obtained by primary treatment of sewage is actually water. To reduce the volume of this sludge, it is allowed to settle. The heavier matter settles to the bottom and the surface liquid is decanted off to obtain the residue.

To separate the water from the sludge there are several techniques that can be employed. These include filter presses, sand drying beds, centrifuges and vacuum filters. By using any of these processes, the water content is reduced; it is then 50 to 80 percent of the sludge. Dry sludge is obtained as a result in the form of sludge cakes.

To further reduce the volume of this sludge, both aerobic and anaerobic digestive processes are employed in decomposing the organic matter in the sludge. A benefit of this digestive process is the stabilization of the sludge which results in the reduction of odor. This sludge is treated again to eliminate harmful microorganisms present, through the use of caustic chemicals. After this treatment, the sludge residue in both liquid and cake form is used as a fertilizer, and spread in fields; the organic matter and nutrients present in the sludge are returned to the soil, in theory. But in practice, Environmental Protection Agencies object to this, as they are unsure of the quality of sludge as manure. Also, very few markets accept such sludge as manure.

The treated effluent from the wastewater treatment plant is discharged into receiving water bodies. To protect these water bodies from contamination, it is essential to carefully manage the treatment process. The incoming influent at the treatment plant, the process of treatment, and the final effluent to be discharged should all be carefully monitored and measured by well trained and certified operators.

There are alternative technologies these days to such sludge production, viz., by digesting the biological sludge.

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Rod Nash is the President of Geostar Publishing  Services LLC. Rod loves net research & blogging. His new blog on Wastewater Treatment is fast becoming popular, as it is comprehensive and well-researched.

Safety And Health Aspects - Waste Water

Generally, all waste-water treatment works, irrespective of their size, have to comply with strict governmental safety and regulations acts. It is the responsibility of the owner or local authority to be fully acquainted with all aspects of the safety guidelines for waste-water treatment operations. The potential danger of an explosion of biogas and air mixtures cannot be over- emphasised, therefore units such as the waste gas burner should preferably be situated at least 15 m away from the gas holder, digester(s) or any buildings, together with due consideration to the prevailing wind.




The health hazards associated with the treatment of waste-water and specifically sludge handling should not be under-estimated. It is the responsibility of the supervisor and the operating staff to acquaint themselves of the dangers and to take the necessary steps to avoid them.

A wide variety of disease-causing organisms are present in both the liquid phase and the sludge stage. Amongst these are salmonella, shigella and vibro that cause diarrhoea and other intestinal tract problems. Viruses are also usually present in waste-water sludges. Amongst these are viruses causing infectious hepatitis, poliomyelitis, sore throats, gastroenteritis and the human immunodeficiency virus (HIV), which can cause AIDS. Protozoa such as entamoeba and giardia that cause intestinal distress are also common in waste-water treatment works. Helminths, such as ascaris (roundworm), taenia (tapeworm) and trichuris (whipworm) are also part of the bio-breakdown process but the ova of these can pass through the body and are fairly resistant to normal treatment processes including anaerobic digestion. Very high counts are usually found in sludge. The ova can survive in sol for several years.

Basic health hygiene rules apply when working in waste-water treatment plants; always wash up properly after working or handling any part of the waste-water treatment system or products. Try to avoid touching your face without washing your hands. Refrain from smoking whilst on the works, it is very easy to ingest disease-causing organisms. Protective clothing is an absolutely essential while working in a waste-water treatment plant especially while working with liquid sludges. Most of the guidelines associated with waste-water treatment are common sense. If one is not sure, every plant should have a code of health and hygiene that can be checked upon to see every health aspect associated with the waste plant.

All waste-water treatment works are classified as factories and must have first aid kit available in-case of accidents. The location of these first aid kits should be prominently displayed as well as the name of the first aid officer assigned to a specific section. It is recommended that all senior operating staff must have completed a basic first aid course. All open wounds should be treated by a doctor and it is important to receive a tetanus injection occasionally due to the types of bacteria workers are exposed to. As a general rule no scratch or cut is too minor to receive proper treatment.

Michael Russell Your Independent guide to Waste Treatments [http://waste-treatments.com]

Will Biogas Power Your Car in the Future?

There are several different types of alternative fuels available for powering vehicles these days and there are more being developed all of the time. Alternative fuels generally cause less pollution and emit fewer greenhouse gases into the environment. Many of them are also cheaper to produce and refine than conventional gasoline and other forms of petroleum. One of these alternative fuels is the non-fossil fuel known as biogas.




This form of fuel is made from the anaerobic digestion of organic matter. It is produced in many landfill sites where organic matter such garden waste and food are present. It can also be made from manure, sewage, and green waste. These components are buried and then compressed in a dark oxygen-free atmosphere. In fact, biogas is still often formed and released into the environment of the earth years after a landfill site is filled in.

Biogas consists mainly of carbon dioxide and methane. However, it may also contain traces of hydrogen, hydrogen sulphide, nitrogen, and possibly even oxygen. If it is processed properly, biogas can be used as a substitute or alternative to natural gas. This means it can be used as an effective fuel for electricity, heating, and cooking, etc.

To collect biogas, the landfill sites need to have gas wells drilled into them. Years ago, the gas was just burnt off. However, more landfills are now being used to collect the substance and the gas is being used as a form of power generation around the world. Some of the landfills have erected dedicated anaerobic digesters which enable them to produce larger quantities of the methane-rich gas at a faster rate, which also cuts down on the amount of waste that needs to be buried in the landfill site.

Another benefit of biogas is the fact that it can be utilized to power various types of vehicles. For example, there is a train in Sweden that is fuelled by biogas which is produced from cow waste and sewage, which contains a lot of methane. The gas is pretty good when it comes to the amount of pollution released as it gives off only one-twentieth of the carbon dioxide that diesel produces. Biogas contains no particulate emissions also only generates one-fifth as much nitrous oxide emissions as diesel.

This bodes well for the future if biogas can be produced, refined and utilized to fuel vehicles across the planet. It is also a renewable fuel therefore it can qualify for certain types of energy subsidies on some regions of the globe. Biogas is being used in various parts of Europe, especially Sweden, to power vehicles such as cars, buses, and trucks and several refuelling stations have been built.

The UK and Germany are two of the leading nations when it comes to the production of biogas. These countries have developed farms and landfills and have constructed several biogas plants as a way to produce it.

While biogas is being generated at a decent rate, the majority of it is used for purposes other than fuel for vehicles. However, this may change in the years to come.

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Benefits of Using Biogas Plants

One of the most recent inventions of energy sources include the biogas plant which produces methane from animal waste and sewage. It is an anaerobic digester that produces fuel from energy crops which are mainly produced for the production of bio fuels rather than for consumption purposes.




Biogas Plant - Wide Range of Uses

A biogas plant has two components mainly the digester and a gas holder. Waste materials are dumped and decomposed in an air tight container called the digester. The bacteria inside the tank decompose the waste materials and form gases like methane, carbon monoxide, nitrogen and hydrogen. These gases are further stored in the gas holder and later on used for vehicle propulsion and heating purposes.

Biogas plant can be constructed in different ways depending on a number of factors like the amount of gas required, the type of digester and the amount of waste available. There are mainly two types of digesters-the continuous feeding systems and the batch feeding systems. The continuous feeding systems feed liquid wastes to the digester whereas the batch feeding systems require solid waste materials.

This particular gas has a number of uses in the modern world. It is used for producing electricity in a cost efficient manner. Moreover, this gas is known to be environment friendly. Biogas  is also considered and used as the best alternative to Compressed Natural Gas or CNG. In many places this gas is also used for cooking food. Today a great number of vehicles are also fuelled by this gas.

Benefits of Using a Biogas Plant

There are substantial benefits of using a biogas plant and some of them are as follows:

Best Fertilizer: this gas plant produces excellent fertilizer rich in nitrogen by processing cow dung. Fertilizer is produced from the biogas digester from organic waste. Such fertilizers contain a large amount of nitrogen than the other conventionally produced fertilizers.

Eco-friendly: biogas plant helps to promote an environment friendly atmosphere by recycling waste products thereby reducing the greenhouse effects. By proper recycling of harmful waste materials, the natural resources are preserved for future generations.

Easy to produce: with the help of these plants, it is easier to produce fertilizers especially in the rural areas. It can be produced quickly and cost efficiently.

Effects on overall health: there are many health benefits related to these gas plants as it recycles waste materials. Studies reveal that the growth of these plants helps to reduce many diseases like respiratory problems, lung diseases, eye infections and so forth. Many of the rural homes use this gas for cooking purposes as it does not produce fumes and smokes thereby reducing health problems.

Excellent fuel: high in calorific value, this gas is used in many vehicles as it is tantamount to diesel. This gas is also rich in methane so it is widely used in cars and other vehicles.

There are a variety of biogas plant manufacturers in the online business portals who supply high quality products of different sizes and prices.

Author has wide knowledge of B2B Marketplace and Business industries. For more information on biogas plant and water treatment plant, visit online business directory Dir.indiaMART.com

Biogas Technology - A Dynamic Approach To The Desertification Challenge In Northern Nigeria

A perspective from Northern  Nigeria.

The evidence of climate change is glaring as the days go by. In Northern Nigeria, continually the environment is loosing grounds to desert encroachment. People living in these environment continually get their source of fuel for energy from wood.




The charcoal from wood is a big business in these part of Nigeria. However, people seems to forget that the wood emanates from the trees in the forest. Despite certain regulations concerning the use of woods, the activities of illegal loggers cannot be entirely supervised or curtailed.

The greatest hindrance to the observance of these regulations is the absence of alternative source of fuel as the use of kerosene is quite expensive for rural dwellers and availability is a problem in some area.

The Chinese has long identified the importance of biogas towards meeting the energy needs in rural areas. Biogas  is produced through anaerobic digestion. The anaerobic production of biogas does not produce any offensive smell hence it is environmentally friendly, reduces green house effect, greatly increases the fertilizer value of manure and protects water source.

Biogas is generated by the activity of anaerobic bacteria. It is composed of 60% methane, 40% carbondioxide and small amount of hydrogen sulphide, nitrogen and hydrogen.

Biogas can be used for cooking, heating, generating electricity and running a vehicle.

The wonders and opportunities associated with biogas appears to be the best alternative along with solar options towards addressing the effect of desertification activities of people in rural area of Northern Nigeria.

In Northern Nigeria, Livestock rearing is a common practice thus raw material for biogas functionality is readily available.

Isaac Akogu is a Pharmacist and a Conversation Map Expert Trainer who commits over 40 hours a week towards diabetes care, counselling, information, education and advocacy for subsidized drugs and treatment for orphans and widows in North Central Nigeria.

Taking Responsibility for Waste!

Although not the most palatable topic, septic or sewer systems are absolutely crucial to a healthy, happy, and sanitary life. There have been many, many scientific and technological developments in the past century or 2, not the least of which is the way we dispose of our waste. We've probably heard of the nothing short of tragic methods many countries around the world used in the previous centuries, but it gives us something to be thankful for if nothing else!




In truth, many epidemics and plagues throughout the 1800's and prior to that as well, have been due to inefficient or sometimes just plain revolting sewage systems. Diseases such as cholera, typhoid, yellow fever, and even malaria are but a few examples of what can happen when waste isn't properly disposed of. Mosquitos are not only responsible for many of these diseases, but interestingly, thrive big-time in sewage-contaminated bodies of water as opposed to purer sources.

Research has proven that mosquitos that are bred in polluted water grow bigger, fly faster, and have an overall lower mortality rate than their more inferior counterparts bred in cleaner water. The "nutrient-enriched" water containing large amounts of ammonia phosphates and other minerals abundant in sewage serve to feed the bacteria and microorganisms that mosquito larvae eat, beefing up their diet, making them healthier and more robust. Another dandy reason to add to the million to keep your waste where it belongs.

The search for ideal waste disposal methods is something man has been up against since the beginning of time. We have certainly come a long way since our ancestors dug holes as their solution, but there is still much we can learn from how things used to be done. Hey, when it comes down to it, a hole in the ground is still the first thing most of us would think of if there wasn't a toilet available! Ok, let's talk about options, assuming modern take-it-for-granted city pipes isn't one of them:

- A hole in the ground right outside your kitchen window.

- A hole in the ground about 30 meters into the woods behind your cabin.

- A pipe leading from your in-house toilet right out to your front street. (History people!)

- A septic system.

Given the choices above, a septic system is probably the system of choice if city sewers weren't available. - Providing you have some kind of environmental conscience that wouldn't allow you to just funnel your sewage down to the closest river. A septic system consists of several key components which together, break your sewage down for safe deposit back into the groundwater. Designing and maintaining a proper septic system is crucial not only for our health, but for our environment as well.

The system starts with piping that leads from your toilet to an underground septic tank. This tank is the the first stage of decomposition where the heavier solids settle to the bottom and the lighter "scum" floats to the top. Tanks often have 2 compartments with a dividing wall between them. The liquid component of the waste will then flow into the second chamber where further settling will take place. This process is then followed by what is called a leach field.

A leach field is a section of land that is used to filter the effluent as it makes its way down through the layers of soil, and eventually into the groundwater. A potential leach field must meet certain "percolation requirements" before being deemed suitable. If the soil is too porous - too much sand and gravel - it won't effectively "hold" and deactivate the harmful pathogens, and conversely, if the soil isn't porous enough - such as too much clay - it won't allow the percolation of waste water at the needed rate.

Tests that are done on the soil for this purpose are called "percolation tests". The size of a given leach field is proportional to the amount of incoming waste water and inversely proportional to the porosity of its soil. Imagine a leach field as a system of perforated pipes stretched out over a wide area of land. These pipes are usually buried under a layer of soil and gravel to prevent animals from accessing. In a well-made leach field, gravity will more or less evenly distribute the effluent load through its piping.

Back in the septic tank, the heavier solids are being decomposed via anaerobic digestion. What the heck is that? Well, it's kinda what makes this whole system even remotely effective. An anaerobic environment is what naturally takes place inside a septic tank when waste is introduced. It's the bacteria that immediately begins eating away at pretty much anything that enters the tank.

One thing to keep in mind though, is that a septic system cannot run on auto-pilot forever. It needs to be regularly maintained for it to continue to run efficiently. There are certain "irreducible" solids that will remain in the tank, and that will gradually accumulate, causing an overflow of the same into the leach field. An overflow of these solids will clog your drain field and cost a right arm to repair.

Other precautions regarding septic systems involve what you can safely flush down your toilet or drains - if other sinks etc are also connected.

- Non-biodegradable substances such as cigarette butts, hygiene products, non-biodegradable toilet paper, etc, cannot be decomposed bacterially, and will only build-up, leading to clogging, overflow, and premature failure of the septic system.

- Oils and greases are more difficult to decompose and can cause clogging and excessive stinking if larger amounts are disposed of.

- Disinfectants, bleaches, and chemicals of any kind have the potential to destroy the anaerobic environment. Do not flush these into your tank!

As a rule, only dump what's absolutely necessary and nothing more. Keep the septic system for your sewage and use other methods such as composting etc for other organic waste instead of using garbage disposers. Perform periodic maintenance on your septic system and have your tank emptied on a regular basis - intervals depend on the size of your tank, the number of users, and your faithfulness - or lack of it - in keeping the guidelines. This is absolutely essential and cannot be ignored.

If you liked my article please visit my websites at Free and Handy and Your Japanese Garden for more, thanks!

What Is Digestate in Anaerobic Digestion During Sludge Treatment?

What is Digestate?

Digestate is the solid leftover of the original matter which is not biodegraded by the anaerobic microorganism. the process of anaerobic digestion forms two products viz biogas and digestate. The quality of digestate is graded against chemical, physical and biological aspects.

Appearance and odour come under physical quality and in chemical aspects heavy metal and some inorganic contaminants are checked.

Hydrolysis begins the digestion process in which the input biodegradable material is broken down to form insoluble organic polymers which are then used by bacterias. Then these are converted to ammonia, hydrogen and carbon dioxide by acidogenic bacteria. On this the Acetogenic bacteria acts that is followed by the process of methanogenesis.

Types of Digestate

Digestate is formed both during the acidogenesis and methanogenesis process. But each by product has different characteristics.

Acidogenic digestate

It is fibrous and consists of lignin and cellulose. This digestate sometimes also contain remains of bacteria and minerals. Also if checked then there is high moisture retention properties in the acidogenic digestate.

Methanogenic digestate

It has very high nutrient content including nitrates and phosphates and it is also called liquor in sludge treatment.

Uses of Digestate

It acts as solid conditioner as it provides soil the organic content. It provides nutrients that are required for the growth of the plant. Acidogenic digestate give rise to composite plastics. Also with digestate plants with resistance towards few diseases have been developed. It stimulates the biological activity of the soil.

Spreading of digestate in ground as such is prohibited but it can be done with sludge spreader. Also for this waste management license is mandatory.

R Oberoi is a portal manager checking out web promotion, content updation and online portal marketing. Check out more about water treatment plants on www.thewatertreatmentplant.com