Advanced Techniques for Effective Waste Water Treatment

Advanced Techniques for Effective Waste Water Treatment

 

Table of contents

 

"  Introduction

 

"  Understanding Wastewater Treatment

 

"  Aerobic Wastewater Treatment

 

"  Anaerobic Wastewater Treatment

 

"  Emerging Technologies in Wastewater Treatment

 

"  Conclusion

 

Introduction

 

Water treatment is a critical process in today’s world, and it’s becoming increasingly essential for both municipal and industrial wastewater. Over the years, we’ve seen significant advancements in wastewater treatment technologies, with the most prevalent being aerobic and anaerobic treatments. In this blog, we’ll delve deeper into these two treatments and the emerging technologies.

  

Peja Waste Water Treatment Plant

 First, we’ll start with the basics of wastewater treatment. Wastewater is any water that has been contaminated with human, animal, or industrial waste. The contamination of wastewater makes it harmful to both humans and the environment. It’s, therefore, essential to treat the wastewater before releasing it back to the environment. Traditional wastewater treatment methods include physical, chemical, and biological treatments. Water is life, and water treatment is an essential process that ensures we can use clean and safe water. Municipal wastewater treatment is an important aspect of water treatment, and it involves the removal of numerous contaminants from water. 

 

Understanding Wastewater Treatment:

Wastewater treatment has come a long way, and tremendous advances have been made to ensure we have safe and clean water. There is a vast difference between the traditional wastewater treatment techniques and what we have now. Advancements include the use of biological processes to break down organic matter, chemical processes to remove nitrogen and phosphorus, and physical processes such as filtration and sedimentation to remove suspended solids. Ideally, the goal is to ensure that the water treatment process produces safe and high-quality water at the end of the process. There are two major wastewater treatment techniques, namely; Aerobic Wastewater Treatment and Anaerobic Wastewater Treatment. While both techniques are useful in treating waste, they differ in how they function.

  

Differences between Aerobic Wastewater Treatment and Anaerobic Wastewater Treatment

 

Aerobic Wastewater Treatment, just as the name suggests, refers to the method of treating wastewater in the presence of air, or rather oxygen. The process involves breaking down organic matter into simpler components through the aid of microorganisms. The microorganisms convert this organic matter into carbon dioxide, nitrites, nitrogen and other components that are much simpler and easier to manage.

Activated Sludge Tank at Peja WWTP

                                         Graphics of Activated Sludge Tank at Peja WWTP

On the other hand, Anaerobic Wastewater treatment refers to the treatment of wastewater in the absence of oxygen. The process involves the breakdown of organic matter into methane, carbon dioxide, and other essential components through the aid of microorganisms that do not require oxygen to live.

Anaerobic Digestor in the background

The overview of Advance water treatment  

The traditional wastewater treatment techniques were relatively inefficient and only removed a limited amount of contaminants from water. But with advancements in technology and environmental concerns, numerous effective techniques have been developed to ensure more efficient and effective water treatment. One of the most significant advancements in wastewater treatment is the introduction of biological nutrient removal. This technique involves the use of specialized bacteria to remove nutrients such as nitrogen and phosphorus from the wastewater. This process results in wastewater with significantly reduced nitrogen and phosphorus levels.

Secondary clarifier

Removal of the surplus sludge from secondary clarifier

Another technique that has gained popularity in recent years is the use of membrane systems such as ultrafiltration, nanofiltration, and reverse osmosis. These techniques are highly effective in removing contaminants such as viruses, bacteria, and other small particles from the water. The Membrane Bioreactor (MBR) is another system that combines both the biological and membrane systems to ensure highly efficient wastewater treatment. This system operates using the same principles as the activated sludge process but involves the use of a separation module that eliminates the need for gravity clarification.

Emerging Technologies in Wastewater Treatment

  

Advanced Oxidation Processes (AOPs) have emerged as an effective wastewater treatment technique. These processes work on the principles of oxidation to break down organic and inorganic contaminants. The process involves the use of UV light or ozone, among other oxidizing agents, to produce highly reactive species that break down contaminants in the wastewater.

Electrochemical treatment has also proved to be highly efficient in treating wastewater. The technique involves the use of electric charges to remove contaminants from the wastewater. It works by oxidizing organic matter, preventing the growth of microorganisms and negating the need for chemicals.

Conclusion

 

Three of the strongest points of a sewage treatment plant are its ability to remove harmful contaminants from wastewater, its contribution to improving public health and environmental sustainability, and its ability to produce biogas that can be used as a renewable energy source. Through various treatment processes, sewage treatment plants can remove harmful pollutants such as bacteria, viruses, nutrients, and chemicals from wastewater before discharging it back into the environment. This helps to protect public health and the environment by reducing the risk of waterborne diseases and contamination of local water bodies. Additionally, through anaerobic digestion, sewage treatment plants can produce biogas that can be used for energy generation, reducing reliance on fossil fuels and contributing to a more sustainable energy future. The ability of sewage treatment plants to remove harmful contaminants from wastewater is absolutely essential for public health and environmental sustainability. It ensures that wastewater does not pollute water bodies or lead to waterborne diseases. In addition to this, the production of biogas using anaerobic digestion is a boon for renewable energy sources. Sewage treatment plants are a great example of how waste can be converted into energy, thereby reducing reliance on non-renewable sources of energy such as fossil fuels. Moreover, the use of renewable energy sources promotes sustainable development and helps to protect the environment for future generations. Consequently, sewage treatment plants are an indispensable part of modern infrastructure, providing benefits for public health, the environment, and energy security.

The Municipal wastewater treatment is an essential process that requires innovative and sophisticated techniques for effective results. With these techniques, it’s possible to transform wastewater into safe and environmentally friendly effluent. This ensures we can use water without worrying about the negative impact it would have on the environment.

Aerobic Wastewater Treatment

 

As the world’s population continues to increase, the amount of wastewater that needs to be treated also increases. Municipal wastewater treatment plants aim to remove contaminants from the water before it is discharged into the environment. One of the most common methods employed at these plants is aerobic wastewater treatment. Aerobic wastewater treatment is a process that relies on microorganisms to break down organic matter in the water. These microorganisms need oxygen to survive, so the wastewater is aerated by being pumped with air or pure oxygen. There are several types of aerobic wastewater treatment systems, including activated sludge treatment, trickling filter systems, and moving bed bioreactors.

One of the oldest and most widely used methods of aerobic wastewater treatment is activated sludge treatment. In this process, the wastewater is mixed with a microbial culture that contains microorganisms that break down organic matter. The mixture is then aerated, and the microorganisms consume the pollutants in the water. The resulting sludge is then separated from the treated water, and the water is released back into the environment. The sludge can be recycled as a fertilizer for crops or disposed of in landfills.

Trickling filter systems are another type of aerobic wastewater treatment system. These systems use a bed of rocks or other materials to provide a large surface area for microorganisms to grow on. The wastewater is sprayed over the top of the bed, and the microorganisms consume the pollutants as the water trickles through the bed. The treated water is then collected at the bottom of the bed and released into the environment.

Moving bed bioreactors are similar to trickling filter systems, but the bed is made up of plastic media that is moved around in the reactor by aeration. This movement ensures that all of the microorganisms in the reactor have access to the wastewater, which results in more efficient treatment. Moving bed bioreactors are often used in smaller wastewater treatment plants because they take up less space than other methods. 

In addition to aerobic wastewater treatment, another common method used in municipal wastewater treatment is anaerobic wastewater treatment. This process relies on microorganisms that do not require oxygen to survive. Instead, they break down organic matter in the wastewater by converting it to carbon dioxide and methane gas. There are several types of anaerobic wastewater treatment systems, including upflow anaerobic sludge blanket treatment, expanded granular sludge bed reactor systems, and anaerobic membrane bioreactors.

Up flow anaerobic sludge blanket treatment, or UASB, uses a large tank that is filled with microorganisms that produce methane gas. The wastewater is fed into the tank from the bottom, and the microorganisms consume the pollutants in the water. The treated water is released from the top of the tank, and the methane gas produced during the treatment process is collected and used to generate electricity.

Graphics of CHP Units that converts biogas in to the electricity

Expanded granular sludge bed reactor systems, or EGSB, are similar to UASB systems, but they use larger, more dense microorganisms that can break down pollutants more efficiently. These systems are commonly used in industrial wastewater treatment because they can handle high levels of pollutants.

Anaerobic membrane bioreactors, or An MBRs, use microorganisms that are able to survive in both aerobic and anaerobic environments. The microorganisms consume the pollutants in the wastewater while also producing methane gas. The treated water is then filtered through a membrane to remove any remaining contaminants, resulting in very clean water.

Overall, the advances in wastewater treatment technologies have made significant progress in treating wastewater and reducing environmental impact. The different types of aerobic and anaerobic wastewater treatment processes enable treatment plants to tackle various pollutants and capitalize on efficient resource recovery opportunities in a sustainable way.

 

The volume of wastewater that needs to be treated rises along with the growth in global population. Before the water is released into the environment, municipal wastewater treatment plants work to remove impurities. Aerobic wastewater treatment is one of the most often used procedures at these facilities.

In the aerobic wastewater treatment process, microorganisms are used to break down organic matter in the water. The wastewater is pumped with air or pure oxygen to supply the oxygen that these microorganisms need to survive. Activated sludge treatment, moving bed bioreactors, and trickling filter systems are a few examples of aerobic wastewater treatment techniques. Activated sludge treatment is one of the oldest and most popular techniques for aerobic wastewater treatment. This procedure involves mixing wastewater with a microbial culture that has microorganisms that degrade organic material. After the combination is aerated, the microorganisms in the water consume the contaminants. Following the separation of the resultant sludge from the cleaned water, the water is subsequently returned to the environment. The sludge can be recycled as a fertilizer for crops or disposed of in landfills. Another form of aerobic wastewater treatment system is one that uses trickling filters. For a vast surface area on which microorganisms can thrive, these systems use a bed of rocks or other materials. The microorganisms ingest the contaminants when the water trickles through the bed while the wastewater is sprayed over the top of the bed. After being gathered at the bed's base, the cleaned water is subsequently released into the environment. 

Comparable to trickling filter systems, moving bed bioreactors have a bed of plastic medium that is moved around the reactor by aeration. The treatment process is more effectively completed because of this movement, which makes sure that all of the microorganisms in the reactor get access to the wastewater. Due to its compact design, moving bed bioreactors are frequently employed in smaller wastewater treatment facilities.

Anaerobic wastewater treatment is another often employed technique in the treatment of municipal wastewater, in addition to aerobic wastewater treatment. Microorganisms that don't need oxygen to survive are used in this method. Instead, they transform the organic materials in the wastewater into carbon dioxide and methane gas to break it down. Anaerobic wastewater treatment techniques include enlarged granular sludge bed reactor systems, anaerobic membrane bioreactors, and up-flow anaerobic sludge blanket treatment. 

Similar to UASB systems, expanded granular sludge bed reactor systems, or EGSB, use larger, more dense microorganisms that may break down contaminants more effectively. Due to their ability to manage significant amounts of contaminants, these systems are frequently utilized in the treatment of industrial wastewater. AnMBRs, or anaerobic membrane bioreactors, employ microorganisms that can live in both aerobic and anaerobic conditions. The bacteria break down the contaminants in the wastewater and release methane gas in the process. After being treated, the water is filtered through a membrane to get rid of any impurities that might still be present. Overall, great progress has been made in treating wastewater and minimizing environmental damage because to technological advancements in wastewater treatment. Treatment facilities are made possible by the various aerobic and anaerobic wastewater treatment methods.

Anaerobic waste water treatment 

As we’ve discussed in the previous section, anaerobic wastewater treatment is one of the ways to treat wastewater. This process is performed in the absence of oxygen, unlike aerobic treatment. Anaerobic treatment has some benefits over aerobically treating wastewater, such as less energy consumption in the process and producing renewable energy in the form of biogas.

Above digestor WWTP Peja

Up flow Anaerobic Sludge Blanket Treatment (UASB) is an anaerobic wastewater treatment process. UASB uses granular sludge, which moves up continuously in the reactor due to the flow of wastewater. The sludge contacts the wastewater, and the bacteria in the sludge start dissolving the organic matter in wastewater under anaerobic conditions. As the wastewater goes up, the microorganisms gradually settle to the bottom of the reactor. Then, the bacteria that settle at the bottom of the tank recycle once again and start the same process for additional wastewater.

 

Expanded Granular Sludge Bed Reactor Systems(EGSB) are also anaerobic wastewater treatment processes, used for breaking down organic matter with the help of microbial communities. High-efficiency granular biomass configurations perform the operation of wastewater treatment along with increasing the longevity of the system. The EGSB reactor comprises three zones as primary organic acid production, secondary organic acid consumption, and tertiary biomass sedimentation. Wastewater flows through the bedside and moves upward in the process. EGSB processes are advantageous because they remove higher organic loading rates and lesser sludge production.

  

Anaerobic Membrane Bioreactors(AnMBRs) is another anaerobic treatment process consisting of a suspended biomass and a membrane. It is quite beneficial when it comes to treating high-strength wastewater. High-strength wastewater is difficult to treat in conventional anaerobic sludge-based reactors. Thus, it is best suited for wastewater treatment with high biochemical oxygen demand (BOD) and chemical oxygen demand (COD) concentrations. The AnMBR process removes these BOD and COD concentrations effectively, making wastewater reusable.

 

With these three anaerobic wastewater treatment processes (UASB, EGSB, and AnMBR), wastewater is treated efficiently, reducing organic matter concentration and making it reusable. Next, we will discuss some exciting emerging technologies in wastewater treatment.

Emerging Technologies in Wastewater Treatment

 

After going through all the advanced techniques for effective wastewater treatment, we can safely conclude that there are numerous ways of treating wastewater. Each method has its advantages and disadvantages, making some of them more suitable for specific situations than others. In summary, we have explored the various forms of wastewater treatment, including aerobic and anaerobic treatments. Both aerobic and anaerobic wastewater treatments have different applications, benefits, and limitations. Still, they all contribute significantly to environmental protection and public health. We have seen how advancements in wastewater treatment technology are providing innovative solutions that are more effective, efficient, and sustainable. These advanced technologies include Advanced Oxidation Processes, Membrane Bioreactors, and Electrochemical treatments. It is worth mentioning that proper operation and maintenance of wastewater facilities are crucial in ensuring optimal performance. Additionally, community education and involvement are essential in promoting a collective responsibility towards sustainable water management. In conclusion, wastewater treatment plays a critical role in protecting public health, the environment, and sustaining our natural resources. With the right technology and management practices, we can efficiently and effectively treat wastewater, thus reducing pollution and conserving our water resources. Let us take a collective responsibility in ensuring environmentally sustainable practices to protect our planet for future generations. Wastewater treatment is a crucial process that aims to remove contaminants from water before being released back to the environment. While various methods exist for treating wastewater, there is no one-size-fits-all approach. With advancements in technology, however, treatment methods are becoming more efficient and sustainable. One such method is the use of Constructed Wetlands, where a specially designed environment helps naturally treat wastewater. Through a combination of physical, biological, and chemical processes, Constructed Wetlands can remove a variety of contaminants from water, including nitrogen, phosphorus, and heavy metals. In addition to treatment technologies, community involvement plays a vital role in protecting our water resources. Awareness campaigns, educational programs, and sustainable management practices can all help improve the efficiency and effectiveness of wastewater treatment. It is vital to understand that untreated wastewater can have far-reaching environmental and public health consequences, making wastewater treatment a critical aspect of our lives. In conclusion, wastewater treatment is a critical process that protects public health and ensures the sustainability of our natural resources. Advancements in technology and community involvement can help improve the efficiency and effectiveness of wastewater treatment. Let us work together to promote sustainable water management practices and protect our planet for future generations.

Peja- Kosovo waste water treatment Plant

Anaerobic waste water treatment Plant- Feasibility report for Dairy plant

Anaerobic waste water treatment Plant, for dairy factory.

With this report design, we'll make an effort to outline the water treatment processes used in the food business, specifically the milk processing plant. The treatment of discharged water can be done in two ways, with aerobic and anaerobic methods. The aerobic method requires larger investments but manages to make the best conversion of matter, which means that the COD (chemical oxygen demand) from 100 kg decreases to 2-10 kg after treatment. The anaerobic method is economically more attractive considering that from this method we can extract usable energy, and the area required for the application of this method is significantly smaller, the COD value from 100 kg decreases to 10-20 kg COD after treatment. It is recommended that the aerobic method be applied as a second stage, to the anaerobic methods, with which the applicable standards for industrial discharged waters are reached.

By the anaerobic method of wastewater treatment, we mean the treatment of waste which is biodegradable with microorganisms without the presence of oxygen. This type of process also occurs in nature, on the subsurface, such as lakes and under the sediment of the oceans, a process known as "anaerobic activity", during this activity methane and carbon dioxide are released.

Anaerobic methods of wastewater treatment can be applied in industry and in households, in which case usable energy can be produced. This type of carbohydrate released during this process can be used as fuel or can be treated to obtain natural biogas. The waste that is created during the treatment of discharged water can also be used as a fertilizer in agriculture. One of the main reasons that developed countries have raised interest in the treatment of discharged water with anaerobic methods, is the release of a large amount of usable energy which is released during this process. This way of treating discharged water has been applied since 30 years ago, in Western Europe. It is worth noting that the surface for the treatment of discharged water with the anaerobic method is much smaller than the surface needed for the treatment with the aerobic method.

Feasibility report for anaerobic waste treatment in Dairy plant

Design, engineering, construction and startup of treatment plant for processing of waste water from dairy production.

The anaerobic digester, biogas conditioning, pipes, pumps, instruments, cabling, and control cabinet are the essential components.

The viability of an anaerobic wastewater treatment system for a dairy business is presented in the document.

This file contains:

1.       1. Basic information on anaerobic technology

2.       2. The dairy industry's waste water technology comparison

3.      3.  Determining the feasibility

      Observation: This document discusses an alternative to aerobic treatment method. Yet, it is determined that anaerobic technology is more alluring from an economic standpoint. After the initial phase of the aerobic system has been developed, it is advised to take into account a second phase of aerobic post treatment.

A.      Anaerobic waste water treatment 

a.1 Anaerobic waste water treatment principles: context

In the absence of oxygen, microbes break down biodegradable material through a variety of processes known as anaerobic digestion. The procedure is used to treat trash, waste water, and to generate energy for industrial or home applications. Food and beverage production accounts for a large portion of industrial use.

Anaerobic activity is the term used to describe the natural occurrence of anaerobic digestion in some soils, lake sediments, and oceanic basin sediments. This is source of marsh gas methane as discovered by Volta in 1776.

The procedure for treating biodegradable garbage and sewage sludge includes anaerobic digestion. In addition, anaerobic digesters can be fed with organic waste from the food and agricultural industries or with crops developed specifically for energy production.

Moreover, anaerobic digestion is frequently exploited as a renewable energy source. Methane and carbon dioxide are the major components of the biogas produced by the process. This biogas can be converted to natural gas or utilized as fuel directly in gas engines for combined heat and power. The solid digestate residues, which are nutrient-rich, can be used as fertilizer.

Anaerobic digestion has gained more attention from governments in a number of nations throughout the world in recent years due to the re-use of waste as a resource and innovative technology approaches that have reduced capital expenditures. In the past 20 years, numerous plants have been constructed for the treatment of sewage sludge and industrial waste fluids. Anaerobic treatment of municipal waste water is also practiced in nations with warm climates. An intriguing feature of anaerobic waste water treatment is that its footprint is significantly less than that of comparable aerobic plants.

a.2 The Anaerobic process

Many microorganisms, such as methane-producing archaea and bacteria that produce acetic acid (acetogens), have an impact on anaerobic digestion (methanogens). These organisms support a variety of chemical reactions and transform biomass into biogas. Aerogenesis, methanogenesis, acidogenesis, and hydrolysis are the four main phases of anaerobic digestion. Chemical reactions can be used to explain the overall process, which involves anaerobic microbes biochemically digesting organic material like glucose to produce carbon dioxide and methane.

 

C₆H₁₂O₆                       3CO₂ + 3 CH₄

During illustrations at Delf  University Amsterdam

Anaerobic treatment process of discharged waters is

1. Hydrolysis

2. Acidification

3. Acidogenesis

4. Methanogenesis

1. Hydrolysis

Biomass occurs in large organic polymer particles that are dissolved, which must be converted into simple monomers. This enables the reaction of bacteria with these organic matter, their chain structure must be destroyed into smaller parts. These monomers, like sugar, are completely permeable to bacteria. So this process of destroying the chain structure of polymers, transforming them into smaller molecules in solution is called Hydrolysis

 

2. Acidification

Acidogenesis is the second of the four stages of anaerobic digestion: it represents the continuous process of breaking down the components by acidogenic bacteria. This is a biological reaction where simple monomers are converted to volatile fatty acids, along with ammonium, carbon dioxide and hydrogen sulphatic.

 

3. Acetogenesis

Acetogenesis represents the third phase of treatment through the anaerobic method by converting it into acetogens, this represents a phase where simple molecules are created through the process of acetogenesis which continue to degrade by converting into acetic acid, carbon dioxide, and hydrogen.

 

4. Methanogenesis

The final phase of the anaerobic wastewater treatment process is Methanogenesis. Here, methanogens use the intermediate products to convert them into methane, carbon dioxide and water. So it represents a biological process where acetates are converted into methane and carbon dioxide, while hydrogen is consumed.

                                                            

Anaerobic Digestor

                                                    Anaerobic conversion of organic matter

B. Configuration of the Reactor for the treatment of discharged water using the anaerobic method

Nowadays, different types of reactors are configured in Europe. But those that are implemented the most are of the most complete mixing type, other types of reactors are with anaerobic filters and those with the creation of the top layer of sludge known as cover (UASB). The types will be explained one by one below.

b.1 Thoroughly mixed reactors

Full-mix reactors actually represent a tank in which discharged water is heated and mixed with an active mass of microorganisms. The amount of fluids entering this reactor is the same as the output, thus maintaining the same level of fluids in the reactor. Microorganisms that form methane and come out of the tank from the digester with the spilled fluids. To achieve an optimal amount of biogas, the flowing fluids should be kept for 20-30 days. Liquid retention can be reduced below 4-6 days when some of the microorganisms return to the digester. In fully mixed systems, solid solids settle in a sieve while the necessary microorganisms are returned to the digester.              

                                                         Thoroughly mixed reactors

b.2. Anaerobic Filter

The anaerobic filter represents a fixed biological layer which is used for the treatment of discharged water, it creates a surface connection where anaerobic microorganisms are found in the form of a biofilm. The treatment is carried out in such a way that the liquids for treatment flow upwards through this fixed layer, so that the pollutants to be treated are absorbed in the biofilm. Anaerobic filters are anaerobic systems that eliminate the need for solids separation and recycling, creating a large amount of sludge and low level of wastewater for treatment. The limitation of anaerobic filters are mainly physical ones related to the deterioration of their surface structure due to the gradual accumulation of non-biodegradable solids. This eventually leads to channelization and short-circuiting of the flow, and therefore anaerobic filters are unsuitable for wastewater with high solids content.

                                                                       Anaerobic Filter

b.3. Anaerobic Upstream Flow Sludge (UASB)

In these reactors, the microbes are continuously suspended (separated) by the flow of liquid which flows from the bottom to the top (uphill). The flow is determined in such a way as to allow the small particles to flow upstream, while preventing the removal of large particles by keeping them in the digester. Microorganisms create the biofilm around the sludge, and methane-creating substances (microbial granules) remain in the digester. The effluent is sometimes returned to the digester being recycled, while maintaining a constant flow from bottom to top (uphill). In these cases of digesters the retention time can be from one hour to one day, while the retention of large solid materials is up to 90 days. In this way, this system is able to separate the solid matter and increase the retention time through the cover created by the sludge.

During illustrations at Delf University Amsterdam

C. Waste water engineers' research

Five dairy enterprises were visited in September 2015 to assess the situation with regard to waste and waste water, as well as to carry out sampling and analysis of the pertinent waste streams. The quantity of whey generated is crucial to the viability of a waste water treatment plant with biogas generation due to the high level of biodegradable elements and, consequently, the great potential for energy production.

A case has been developed to evaluate the viability of biogas plants at the dairy sector based on the findings of the study and analyses. The economics of the investments, taking into consideration the costs and advantages, in particular the value of energy and the profits that arise, are the main emphasis of the feasibility study.

D. Comparison of treatment technologies for the dairy industry

It is possible to use biological, chemical, or physical methods to treat the wastewater from a dairy industry.

The advantage of physical and chemical processes is that they frequently take up little space and can be found inside of closed structures. Nevertheless, these procedures have drawbacks in that they utilize a lot of chemicals and generate a lot of sludge, which must then be disposed of. Running expenses for these procedures are comparatively expensive due to chemical prices and sludge disposal costs.

The harmful elements in garbage and waste water will undergo natural biodegradation during biological processes. As has been shown throughout the world, a biological process can be the best and most economical method of treating dairy waste water if the right system is selected and built appropriately.

Anaerobic and aerobic biological systems can be distinguished from one another. In aerobic systems, the oxygen in the water must be supplied with energy in order for the organic contaminants to decompose through biodegradation. Without oxygen, anaerobic bacteria will biodegrade organic contaminants in anaerobic systems, producing biogas in the process.

Aerobic System

Feasible for waste water

Low temperatures 10-20 ⁰C

Low COD strength

Treatment efficiency

More than 95 %

Possible to meet standards for discharge at surface water                                                                   

By product A lot of sludge

 

Anaerobic System

Feasible for waste water with:

Medium/ high strength/ COD

 Medium temperature around 30 ⁰C

Treatment efficiency: Around 85%

To meet standards for discharge at surface water additional aerobic treatment is needed                                                                               Biogas highly desired

Operating expenses

High (Aeration- costs)

Small amount of energy used, small costs for sludge removal.

d.1. Anaerobic and aerobic systems are compared in terms of cost

Whey, which is highly concentrated have a temperature of 30 ⁰C, in case is added lot of cleaning and rinsing water, create less concentration and has a lower temperature. To meet the requirements for discharge at surface waters, there are two methods for biological waste water treatment.

1.)    Aerobic treatment of the waste water

2.)    Anaerobic treatment of the waste water with an additional aerobic treatment of the anaerobically treated waste water.

Investment expenses for the two strategies are equivalent. The operating costs, particularly the energy expenditures, are the most significant difference.

Basis assumption:

Ø  COD load waste water is 1440 COD / day

Ø  300 production days per year

Ø  Hydraulic load about max 50 m³ day estimation

Ø  80 % of the biogas produced can be used effectively as an energy source in the factory or in another way

 The contamination in the wastewater is comparable to that of a small town with 15.600 residents.

Aerobic Treatment          Anaerobic treatment waste water an aerobic post treatment

                                       Net production of CH₄ gas;349 Nm^3/day                                                              

                                         CH₄ gas used effectively 279 Nm^3/ day

Costs aeration energy       which corresponds with 299 l diesel/day

25.920 euro/ year             Profit 83.520 euro/ year

Sludge production 151.200 kg Cost energy for aeration in post treatment system 3.900 €/day

Dry solids / year or 5.040 m³year   Sludge production 21.600 + 22.800= 44.400 kg dry solids/ year

                                                                                or 432 + 760= m1.192 m³ / year

Due to energy expenses associated with aeration, full aerobic treatment of wastewater results in a yearly cost of 32.000 euros, whereas anaerobic treatment followed by aerobic post-treatment results in a profit of 82.500–3.900=78.620 euros.

Calculation:

d.1.1 Aerobic treatment

Oxygen demand is 1440 (COD load) x 0.60 (COD in sludge 35%) and rest COD (5%)= 864 kg O₂/ day.

Specific energy demand of aeration is about 0.8 kWh/ kg O₂.

Total energy demand aeration is 691 kWh / day. Costs are 691 x 0.12= 83 euro/ day.

Total costs are 300 x 83= 25,920 euro/ year.

Sludge production: 0.35 x 1440= 504 kg dry solids/ day or 504 x 300 =151,200 kg/ year is 5,040 m³sludge/year (sludge 3% dry solids).

d.1.2. Anaerobic treatment and Aerobic post treatment

Biogas production from anaerobic treatment: 1,440 x 0,8 (85% COD efficiency + 5 % COD in waste sludge) x 0,35 (specific gas production 0.35 Nm^3/ kg COD removed) is 403 Nm³ gas CH₄/ day.

To keep reactor content at 30 ⁰C to 35 ⁰C, methane gas has to be used for heating of the waste water. It is assumed that the wastewater has to be raised 10 degrees in temperature. Energy need is 10 x 50 x 4,2 (energy raise 1 m³ 1 ⁰C is 4.2 MJ)= 2100 MJ per day which corresponds with 2100/ 38,6= 54 m³ methane gas. Net gas production is 403- 54= 349 m³/day

Gas used effectively 0.8 x 349= 279 Nm³/ day.    

1 Nm³ CH₄ gas corresponds with 1.07 l diesel, 279 Nm³ gas corresponds with 299 l diesel. Costs diesel are 1.1 euro /l

Yearly profit is (production 300 days a year) 300 x 299 x 1.1 = 98,670-euro year

Production sludge 0.05 x 1440 = 72 kg dry solids / day or

300 x 72 = 21,600 kg dry solids/ year is 432 m³ sludge (sludge 5% dry solids) 

d.1.4. Aerobic treatment

COD load of aerobic post treatment is 0.15x 1.440= 216 kg COD / day.

Oxygen demand is 216 (COD load)x 0.60 (COD in sludge 35% and rest COD 5= 130 kg O₂/ day.

Specific energy demand aeration is about 0.8 kW/ kg O₂.  

Total energy demand aeration is 0.8 x 130= 104 kW/ day Costs are 104 x 0.12= 14 euro day

 Total costs 300 x 14 = 3900 euro / year

Production sludge 0.35 x 216= 76 kg dry solids / day or 300 76 = 22,800 kg dry solids/ year is 760 m³ sludge (sludge 3% dry solids). 

 E. Data on waste water and design

Information on waste water

The following input data and fundamental assumptions were used to calculate the anaerobic waste water treatment system's viability.

 

ü  There are two main waste products from the cheese-making process: concentrated whey waste and waste water, which includes cleaning fluids.

ü  Milk processed 24 m³/ day during 12 hours per day and 6 days per week (with extension 30 m³).

ü  Production of whey: 20 m³/ day, COD whey is approximately 68.000 mg/ l and sulfate SO₄ concentration 1100 mg/ l

ü  Production of waste water: 51 m³/ day, COD waste water approximately 4000 mg/ l and sulfate SO₄ concentration 500 mg/ l.

ü  Waste water and whey are both treated by the system.  

ü  To keep the reactor content at 30- 35 C, methane gas has to be used for the heating of the waste water. I am assumed that, in average, the temperature of the waste water is 20- 25 C and has to raise by 10 degrees in temperature.

ü  Biogas will be recovered and will be used for heating purposes and will so substitute the use of diesel oil. Biogas can be used for heating of the waste water and for production of the hot water.

F. Basic design information

Building

Local earthquake regulations will be followed during the construction of the plant. Concrete will be used to build the foundations, hydrolysis ring, and digester tanks. Pumps, a control unit, flares for biogas, and other control equipment will all be supported by concrete.

 

Design guidelines 

1.       Two stage treatment process: mixing/ hydrolysis (MHT), anaerobic digestion (AD).

2.       WWT plant design is based on existing processing capacity.

3.       Plant is capable to handle all effluents from dairy factory.

4.       Input material waste water free of stones and other obstructive material.

5.       Input material is provided mainly during daytime (16 hours per day).

6.       Mixing of the collection tank is not provided. Volume 20 m³ with feed pumps.

7.       The temperature of the anaerobic digester sludge is set to 30 ⁰C (mesophilic temperature range). No heating of the digester will occur, but heating of the waste water in the mixing tank is possible.

8.       Anaerobic digester volume 150 m³, provided with sludge/ biogas/ effluent separator and gas roof.

9.       The bacteria within the fermenter transforms the organic material into biogas.

10.   The biogas is stored underneath the flexible roof which consist of a membrane.

11.   Desulphurization device is provided on basis oxygenation of hydrogen sulphonyl in biogas.

12.   Conditioning of biogas by automatic Colling device.

G. Construction of the waste water treatment

The proposed technology is based on aerobic biological treatment process, which consists of:

Step 1: reception – conditioning tank (MHT)

Step 2: anaerobic digestion tank (AD)

Step 3: biogas conditioning system (BC)

The output from the waste water treatment system will be:

a)       Biogas with high calorific value

b)      Treated effluents

c)       Biological sludge

                                                                        Anaerobic digestor

G. 1. Services and apparatus

 The following apparatus and services are included in the project

1.       Design and Engineering

2.       Collection and hydrolysis in to the mixing tank.

3.        Anaerobic digester, including piping, instruments and controls

4.       Biogas conditioning unit

5.       Civil work design and support structures.

6.       Construction management, project coordination.

7.       Biological process monitoring

8.       Manual and documentation.

9.       License and permits. 

Conclusion

    The use or treatment of the whey that is released during cheese processing is one of the biggest concerns nowadays. Considering that it contains large amounts of organic matter, and considering the large amount released during cheese production, this represents a serious problem for the environment. However, the potential production of biogas (methane), hydrogen or other marketable products, with simultaneous high COD reduction through proper treatment proves that the whey which is released during cheese production should be considered as a source of energy and non-polluting. The presence of biodegradable components in whey, together with the advantages of anaerobic processes, makes the anaerobic treatment method more attractive for whey treatment. This project aims to examine the most representative applications that are currently being carried out in whey, which processes are being perfected based on the scientific studies that are being developed.

Waste water treatment Plant