All About Anaerobic Digestion

Anaerobic Digestion

Presented by PureTerra Ventures

OVERVIEW

Overview

History

Process

Technologies

AD Systems

O&M

Advantages

Drawbacks

Applications

Regulations

Market Overview Deals

Anaerobic Digestion: Overview

What is AD?

AD is a natural process in which microorganisms break down organic materials

“Organic” means coming from or made of plants or animals. This may include animal manures, food scraps, fats, oils & greases, industrial organic residuals and sewage sludge (“ biosolids ”)

What are “organic materials”?

Where does it take place?

Anaerobic digestion takes place in closed spaces where there is no air (or oxygen), hence the name “anaerobic”

When microorganisms break down or eat the organic materials biogas is generated. The material that is left after the process is called digestate which is rich in nutrients and can be used as fertilizers/soil amendments When microorganisms break down or eat the organic materials biogas is generated. The material that is left after the process is called digestate which is rich in nutrients and can be used as fertilizers/soil additives

What is the result of the process?

What is the result of the process?

3

Sources: EPA, Geograph

HISTORY

Overview

History

Process

Technologies

AD Systems

O&M

Advantages

Drawbacks

Applications

Regulations

Market Overview Deals

History of AD

Jan Baptita Van Helmont determined that flammable gases could evolve from decaying organic matter Principle Discovery

1600 s

Count Alessandro Volta concluded that there was a direct correlation between the amount of decaying organic matter and the amount of flammable gas produced Direct Correlation Established

1776

Sir Humphry Davy determined that methane was present in the gases produced during the AD of cattle manure Methane Detected

1808

First digestion plant was built in Mumbai, India First Digestion Plant

1859

Source: PennState Extension

5

1895

Biogas was recovered from a "carefully designed" sewage treatment facility and used to fuel street lamps in Exeter AD Reaches UK

First dual-purpose tank for both sedimentation and sludge treatment installed in Hampton First Dual-purpose Tank

1904

1930 s

The development of microbiology as a science led to research by Buswell and others o identify anaerobic bacteria and the conditions that promote methane production Identification of Anaerobic Bacteria

1970

China has 6 million small scale digesters on farms Traction in China

First in the USA - by Cornell University Plug Flow Digester developed in USA

1978

6

Source: PennState Extension, Anaerobic Digestion and Bioresources Association

2000

German Renewable Energy Act passed into law setting a feed-in tariff for electricity production German Regulations

UK Regulations

2002

Renewables Obligation introduced in England, Scotland & Wales - electricity suppliers to increase production of electricity from renewable sources

UK Climate Change Act

2008

First legally-binding framework to cut carbon emission. Sets 80% cut in greenhouse gas emissions by 2050

2010

Feed-in tariffs for renewable energy introduced in the UK UK Regulation Update

Recognition of AD Benefits

2011

7 Defra’s Waste Review: AD realizes “greatest environmental benefit” of any treatment option for inedible food wastes

Source: Anaerobic Digestion and Bioresources Association

PROCESS

Overview

History

Process

Technologies

AD Systems

O&M

Advantages

Drawbacks

Applications

Regulations

Market Overview Deals

Process Illustration

Heat

Electricity

Livestock Waste

Biogas

Bio- methane

Crops

Waste- water

Anaerobic Digester

Fuel

Gas Grid

Food Waste

Digestate

Fertilizers/Soil Amendments

Livestock Bedding

9

Sources: Environmental and Energy Study Institute

• Broadly, the Anaerobic Digestion process can be broadly segregated as a “two-stage” process as there are two types of bacteria each relying on each other. These two stages are continuous processes till the second stage results in stabilization. • In the first phase, organic material is changed by acid forming bacteria to simple organic matter • In the second phase, methane-forming bacteria use organic acids to produce Carbon Dioxide and Methane. The acid is used in the rate that it is produced. • The digestion process results in the following products: Process Overview

Digested Sludge which is the final

Supernatant which is the liquid high in

Gases which can be utilized for heating digester/buildings, running engines and for electrical power

Scum which are the lighter solids floating from gas entrapment. If it builds up it can reduce the capacity

“stabilized” product containing inorganic solids and not easily digested organic solids

solids, BOD & ammonia and

typically recycled through the plant

Sources: Michigan Department of Environmental Quality, The Water Network

10

Detailed Stages in Anaerobic Digestion

Complex organic matter, Carbohydrates, Fats & Proteins are broken down into glucose molecules, fatty acids and amino acids This stage is carried out by hydrolytic eco-enzymes (such as cellulase, amylase, protease and lipase) exerted by fermentative microorganisms Some products of hydrolysis such as hydrogen and acetate may be used by methanogens. However, majority of the molecules produced are relatively large and must be further converted to smaller molecules for production of methane

Acetic Acid

Sugar, Amino Acids & Fatty Acids

Carbs, Proteins & Fats

Volatile Fatty Acids

Methane & Carbon dioxide

Relatively slow step - can limit the rate of the overall process

H 2 and CO 2

1

3

2

4

Acidogenesis

Acetogenesis

Methanogenesis

Hydrolysis

11

Sources: Anaerobic Digestion and Bioresources Association, Anaerobic Technology in Pulp and Paper by P. Bajpai, Washington State University Extension

Detailed Stages in Anaerobic Digestion

Acetic Acid

Bacteria break down glucose molecules, fatty acids & amino acids into volatile fatty acids & alcohols resulting in byproducts like hydrogen sulphide, carbon dioxide and ammonia The organic are converted by acid-forming bacteria to higher organic acids such as propionic acid, butyric acid and to acetic acid, hydrogen and carbon dioxide

Sugar, Amino Acids & Fatty Acids

Carbs, Proteins & Fats

Volatile Fatty Acids

Methane & Carbon dioxide

H 2 and CO 2

2

3

1

4

Hydrolysis

Acetogenesis

Methanogenesis

Acidogenesis

12

Sources: Anaerobic Digestion and Bioresources Association, Anaerobic Technology in Pulp and Paper by P. Bajpai

Detailed Stages in Anaerobic Digestion

Acetic Acid

Volatile fatty acids & alcohols are converted into hydrogen, carbon dioxide and ammonia Higher organic acids produced during acidogenesis are subsequently transferred to acetic acid and hydrogen by acetogenic bacteria It is not always possible to draw distinctions between acidogenic and acetogenic reactions. Acetate and hydrogen are produced during acidification and acetogenic reactions and both of them are substrates of methanogenic bacteria

Sugar, Amino Acids & Fatty Acids

Carbs, Proteins & Fats

Volatile Fatty Acids

Methane & Carbon dioxide

H 2 and CO 2

3

1

2

4

Hydrolysis

Acidogenesis

Methanogenesis

Acetogenesis

13

Sources: Anaerobic Digestion and Bioresources Association, Anaerobic Technology in Pulp and Paper by P. Bajpai

Detailed Stages in Anaerobic Digestion

Archaea convert hydrogen and acetic acid into methane and carbon dioxide

Methane is produced by methanogenic bacteria which are capable of metabolizing formic acid, acetic acid, methanol, carbon monoxide, and carbon dioxide and hydrogen into methane The methanogenic bacteria are crucial to anaerobic digestion process since they are slow growing and extremely sensitive to the changes in the environment and can assimilate only a narrow array of relatively simple substrates Methanogenesis is a critical step in the entire anaerobic digestion process, and its biochemical reactions are the slowest in comparison to those in other steps. Methane-producing bacteria are strict anaerobes and are vulnerable to even small amounts of oxygen

Acetic Acid

Sugar, Amino Acids & Fatty Acids

Methane & Carbon dioxide

Carbs, Proteins & Fats

Volatile Fatty Acids

H 2 and CO 2

4

1

2

3

Hydrolysis

Acidogenesis

Acetogenesis

Methanogenesis

14

Sources: Anaerobic Digestion and Bioresources Association, Anaerobic Technology in Pulp and Paper by P. Bajpai

TECHNOLOGIES

Overview

History

Process

Technologies

AD Systems

O&M

Advantages

Drawbacks

Applications

Regulations

Market Overview Deals

AD Technologies Used Globally

Liquid Anaerobic Digestion

High Solids Anaerobic Digestion

Plug Flow Anaerobic Digestion

High Rate Anaerobic Digestion

Micro Anaerobic Digestion

Co-digestion

Sources: Maple Reinders, Geograph

16

Liquid Anaerobic Digestion

• Designed to process a dilute organic slurry with typically <15% total solids • Successful track record in treating low solid materials such as sewage sludges and food industry effluents • Require comparatively larger digesters, more and greater capacity water pumping and piping/valving, more extensive digestate storage and / or de-watering, higher capacity wastewater treatment facilities and more energy required to heat the larger volumes • Providing that the above points are considered at the design stage, a wet system can provide an effective and robust means of treating low solid content waste, or high solid waste that has been adjusted to <15% total solid content

Some companies offering Liquid Anaerobic Digestion Tech

Sources: Biogas World, Wales AD Centre

17

High Solids Anaerobic Digestion

• High-solids systems can handle up to 35 percent solids, which could be some materials other than organics, though at a minimumSuccessful track record in treating low solid materials such as sewage sludges and food industry effluents • More expensive than liquid digestive systems • Municipalities and waste haulers tend to select this system type because of a higher solid, higher contaminant mix

Some companies offering High Solids Anaerobic Digestion Systems

Sources: Waste360

18

Plug Flow Anaerobic Digestion

• Can be considered a type of high solids anaerobic digester - it can handle greater amounts of solids than both a covered lagoon and a complete mix digester • Total solid content of input should be at least 15% to as high as 20% • The contents within the plug flow digester are thick enough to keep particles from settling to the bottom of the tank • Plug flow digesters do not require mechanical mixing as in other types of digesters • Hydraulic retention times are generally in the 15 days to 21 day time-frame

Some companies offering Plug Flow Anaerobic Digestion Tech

Sources: Renewable Energy Institute

19

High Rate Anaerobic Digestion

• System where liquids stay in the digester for a short period of time; where-as, solids are held longer. This allows for a smaller reactor size, while maintain high gas production • Decouples the hydraulic retention time (HRT) from the solids retention time (SRT) • Methane-forming microorganisms are trapped in the digester to increase efficiency • High rate systems are more commonly used and are characterized by supplemental heating, auxiliary mixing, uniform feeding rates, and sludge thickening before digestion

Some companies offering High Rate Anaerobic Digestion Tech

Sources: Environmental Energy & Engineering Co., Extension.org, American Biogas Council, Environmental Expert, Environmental Resources Center

20

Micro Anaerobic Digestion

• Micro anaerobic digesters can be applied to anywhere where there is a need and benefit for AD but a full-sized system wouldn’t be appropriate because of cost and footprint constraints • It is generally anticipated that micro scale biogas plants are on farm installations using only own (waste) biomass resources, where livestock manure is a main source • Micro-scale digestion involves the production of biogas, but on a small scale within farms • The small-scale digestion production units are below 80 kW

Some companies offering Micro Anaerobic Digestion Tech

Sources: Decisive2020.eu, Biogas World, Bioenergy Farm

21

Co-digestion

• Co-digestion is the simultaneous digestion of a homogenous mixture of two or more substrates. Traditionally, anaerobic digestion was a single substrate, single purpose treatment • The most common situation is when a major amount of a main basic substrate (e.g. manure or sewage sludge) is mixed and digested together with minor amounts of a single, or a variety of additional substrate • The use of co-substrates usually improves the biogas yields from anaerobic digester due to positive synergisms established in the digestion medium and the supply of missing nutrients by the co- substrates

Some companies offering Co-digestion Tech

Sources: IAState.edu

22

AD SYSTEMS

Overview

History

Process

Technologies

AD Systems

O&M

Advantages

Drawbacks

Applications

Regulations

Market Overview Deals

Types of AD Systems

There are many types of AD Systems depending on different classification methods as highlighted on this page

Loading Schedule

HRT

SRT

Flow Pattern

Batch

Continuous

Classification Methods

Complete Mix

Mixing

No Mixing

Thermophili c

Temperature Regime

Mesophilic

Sources: South Dakota State University

24

Some of the Commonly Used AD Types

Some of the commonly used AD System Types

Complete Mixed Reactors

Mixed Plug Flow Reactors

Covered Lagoons

Up-flow Anaerobic Sludge Blanket

Fixed Film Anaerobic Digester

Sequential Batch Reactor

25

Sources: Washing State University Extension, HoSt Bioenergy

Complete Mixed Reactor (CMR)

Overview:

• Covered tank with mixing

Biogas

• Heated

• Mesophilic or Thermophilic Range

• 15-20 Day HRT

• 2-10% Solids Input

Advantages:

• Efficient

• Can digest different levels of dry matter content

• May take energy crops

• Good mixing

• Good solids degradation

Disadvantages:

• No guarantee on how much time the material spends in the tank

• Mechanical mixing requirement

26

Sources: South Dakota State University, Environmental Resources Center

Mixed Plug Flow Reactors

Overview

Horizontal plug-flow reactor design incorporates progressive steps of narrow vertical mixing using gas injections throughout the length of the long rectangular channel

Advantages:

• Inexpensive

• Simple to operate

• Can take energy crops

Disadvantages:

• Hard top difficult to open to remove settled solids

• Membrane top subject to weather (wind and snow)

Biogas

Effluent

Feed

Axial Mixing

27

Sources: Washington State University Extension, Environmental Resources Center

Covered Lagoon

Overview

Disadvantages:

Anaerobic digester reactor design that is made up of a lined pit and a flexible plastic cover. This system captures biogas under an impermeable cover, while taking advantage of the low maintenance requirement of a lagoon.

• Poor mixing

• Poor energy yield

• Large footprint

• Cover maintenance impacts life of the system

Advantages:

• Solids settling reduces useable volume

• Inexpensive

• Bacteria can wash out if short circuiting occurs

• Easily adapted to hydraulic flushing

• Limited to warmer weather or warm climates since digestion depends on temperature

• Simple construction and management

Biogas

Feed

Effluent

28

Sources: Washington State University Extension, Environmental Resources Center

Up-flow Anaerobic Sludge Blanket

Overview:

Biogas

Anaerobic digester reactor design that uses an up-flow regime to develop dense granular sludge, which allows for high volumetric loadings

Advantages:

• Provides high removal efficiency even at high OLR and low temperature and therefore requires smaller reactor volume • Simple construction and low operation and maintenance cost due to local availability of construction material and other parts • Simple construction and low operation and maintenance cost due to local availability of construction material and other parts

Disadvantages:

Sludge Blanket

• Needs post-treatment as pathogens are not removed completely

• Long startup time is required due to the slow growth rate of microorganisms in case activated sludge is not amply available

• Odor, toxicity, and corrosion problem

29

Sources: Hindawi, South Dakota State University

Fixed Film Anaerobic Digester

Overview:

Biogas

• A fixed film digester is essentially a column packed with media, such as wood chips or small plastic rings

• Methane forming microorganisms grow on the media

• Manure liquids pass through the media

Advantages:

• Efficient

• Low bacteria wash out

• High gas production per volume

Treatment Media

Disadvantages:

• Suspended solids must be removed

• Expensive

• Plugging of bacterial growth media

• Lower gas production due to removed solids

Drain

30

Sources: Environmental Resources Center

Sequential Batch Reactor

Overview

Disadvantages:

Variation on an intermittently mixed digester. Methane forming microorganisms are kept in the digester by settling solids and decanting liquid. It operates in a cycle of four phases.

• Complex orientation

• Relatively expensive

• Low gas yield per reactor volume

• Works best with low solids substrate

Advantages:

• High gas yield per substrate load

• Works well with dilute manure

• Small reactor size

• Can accept high energy liquid co-digestion products

Feed Pump

Air Pump

Aeration Reactor

Storage Tank

Effluent Tank

Filling Tank

Settling Tank

31

Sources: Environmental Resources Center

O&M

Overview

History

Process

Technologies

AD Systems

O&M

Advantages

Drawbacks

Applications

Regulations

Market Overview Deals

Factors Affecting Anaerobic Digestion

Bacteria Must have enough living organisms and the two different types bacteria types required in balance

Waste Solid concentration and frequency of feeding can impact the process

Contact Stabilization cannot occur without actual contact of the bacteria with the food. This contact can take place in several ways but the most effective is mixing. Mixing can be achieved artificially by mechanical mixers or by natural means. Time Two main factor may be considered in this aspect namely hydraulic retention time (HRT) and the solids retention time (SRT). SRT depends on the degree of sludge retention achieved and HRT. The SRT/HRT ratio, therefore, directly implies the efficiency of a treatment system. Higher the ratio, more efficient and economic the system

Temperature The rate of food stabilization increases and decreases with temperature within certain limits

pH The pH of the contents of a digester depends on the relationship between the volatile acid, alkalinity and percentage of carbon dioxide in the digester gas. Many reporters have indicated that the optimum pH for the digestion of organic waste is in the range 6.8 to 7.2 with the limit of the range for operation without significant inhibition being 6.5 to 7.6

pH

Toxics Inhibitory effects of certain materials on digestion if their concentration become too high

33

Sources: Environmental Information System, Michigan Department of Environmental Quality

Key Ops & Control Parameters

Bacteria

Loading

Amount applied to the treatment process should be according to system size

Maintain adequate quantity & plan for restart

Temperature

pH

Temperature strongly influences many factors affecting all stages of microbial activity and especially methane and VFA production

Methanogens are sensitive to variations in pH and it is critical to maintain the correct pH range for efficient operations

Food

Alkalinity

Sources of alkalinity like ammonia and bicarbonate are produced during digestion and help maintain pH. A well-performing digester should not require alkalinity supplementation

Minimize amount of inorganic entering and eliminate toxic material

34

Sources: Michigan Department of Environmental Quality, American Biogas Council, Water Environment Federation

Maintenance Overview

Minimizing Odor

Maintaining Safe Workspaces

Minimizing Tank Foaming

Tank Cleaning

Odorous compounds such as hydrogen sulfide and ammonia are produced during digestion. The installation of digester tank covers limits the effect of nuisance odors to the surrounding environment

Biogas is a flammable substance. The lower explosive limit (LEL) for methane in the air is 5%. Furthermore, empty digesters are classified as confined spaces. The immediately dangerous to life or health (IDLH) limit for methane in the air is 0.5%. To ensure safety and minimize risk, air monitors should be installed where appropriate and operators should follow all safety precautions when working around digesters and related equipment.

Foaming impairs performance by reducing the active digestion volume; this may lead to lower volatile solids reduction and biogas production, short circuiting of pathogens, mechanical equipment damage, and foam overflows or spills. Foaming may result from the presence of chemical surfactants, biological surfactants, or filamentous organisms. Foaming may be exacerbated by unstable operations such as highly variable loading rates or mixing. Maintaining constant digester feeding (rather than loading in batches) helps limit tank foaming issues

Digester tanks should be removed from service periodically for cleaning and inspection. While offline, operators can check or repair any mechanical equipment installed within the tank and inspect the tank itself for structural deterioration. Additionally, grit and scum, accumulates within digestion vessels and limits effective/treatment volume, and should be removed while the tank is offline.

35

Sources: Water Environment Foundation

Other Maintenance Practices

Maintenance Item

Description

Frequency

An anaerobic digester system must be cleaned and removed of excess sludge. In well-designed systems, this is performed automatically with very little downtime. Other designs require manual removal of waste

Sludge Removal

1 to 2 years

3 to 6 months

Pump Clearing

When pumping high solids content waste, it is important to ensure that pumps are cleared of debris regularly

It is important to remove the corrosive hydrogen sulfide compounds to avoid engine replacement if biogas collected from the digesters is being refined and used for electricity generation. This can be done by passing the biogas through iron packing material.

6 to 12 months

Iron Packing Replacement

General Engine Maintenance

The generator producing electricity from the anaerobic digester must be inspected for proper fluid levels

Weekly

Preventative Engine Maintenance

The electrical, fuel and air intake systems must also be inspected for each of the gen sets

Monthly

To avoid safety hazards, it is recommended that the valves on the digestion system be checked for leaks one to two times a year. Improperly working valves should be replaced as soon as possible

6 to 12 months

Valve Leak Checks

Pipes must be checked for leaks at least once per year. It is also important that no open flames are anywhere near inflow or outflow pipe lines.

6 to 12 months

Pipe Leak Checks

Any nonmetal fitting (i.e. ducted vents, plastic valves, rubber fittings) located on the gas or waste pipeline must be inspected 6 to 12 months

Fittings Leak Checks

36

Sources:Exploring Energy Efficiency & Alternatives

ADVANTAGES

Overview

History

Process

Technologies

AD Systems

O&M

Advantages

Drawbacks

Applications

Regulations

Market Overview Deals

Advantages of Anaerobic Digestion

Environmental Benefits

Energy Benefits

Economic Benefits

• Elimination of malodorous compounds • Reduction of pathogens • Deactivation of weed seeds • Production of sanitized compost • Decrease in GHGs emission • Promotion of carbon sequestration • Beneficial reuse of recycled water • Protection of ground/surface water

• Net energy producing process • Biogas facility generates high quality renewable fuel • Surplus energy as electricity and heat is produced • Reduces reliance on energy imports • Such a facility contributes to decentralized, distributed power systems • Biogas is a rich source of electricity, heat, and transportation fuel

• Transforms waste liabilities into new profit centers • Time devoted to moving, handling and processing organic waste is minimized • Adds value to negative value feedstock • Income can be obtained from the processing of waste (tipping fees), sale of organic fertilizer, carbon credits and sale of power • Power tax credits may be obtained from each kWh of power produced • Biomass-to-biogass reduces water consumption • Reduces dependence on energy imports

38

Sources: Cleantech Loops

DRAWBACKS

Overview

History

Process

Technologies

AD Systems

O&M

Advantages

Drawbacks

Applications

Regulations

Market Overview Deals

Drawbacks of Anaerobic Digestion

Slow start up

Production of explosive gas

Close monitoring required

Extreme confined space hazard

Sensitive to temperature, load and toxicity

Heating, mixing, gas collection equipment & plumbing adds cost, complexity

High BOD and P in supernatant

Cleaning & maintenance difficult with sealed tanks

40

Sources: D Hill Environmental

APPLICATIONS

Overview

History

Process

Technologies

AD Systems

O&M

Advantages

Drawbacks

Applications

Regulations

Market Overview Deals

Some Industrial Applications of AD

Wastewater Treatment Plants

Pharmaceutical Industry

Food & Dairy Industries

Municipal Solid Waste Management

Chemical Industry

42

Sources: Anaerobic Digestion: Industrial Applications by D.Nally, S.Smith, F.Hackett, H.Mooney; EPA, Sciencing, Republic Sales, Urban News Digest, LookForDiagnosis

Municipal Solid Waste Management

• Treatment of municipal solid waste is a major challenge of modern society • This waste is associated with pollution, bad odors and high expenditure • Simultaneous digestion of organic fraction of municipal solid waste together with sewage sludge under mesophilic conditions is regularly used in several countries • This process is routinely performed, after rough screening, by conveying the solid waste to a WWTP where it is partially treated • The resulting mixture is then submitted to digestion • Although the process for this specific application has been available since the mid 1980s, most of the initial commercial application was limited to Europe driven by higher dependency on foreign oil (and hence greater stress on alternative fuel), higher fossil fuel prices and severe land space constraints

43

Sources: Anaerobic Digestion: Industrial Applications by D.Nally, S.Smith, F.Hackett, H.Mooney

Wastewater Treatment Plants

• Anaerobic digestion of municipal wastewater sludge has been widely practiced since the early 1900s and is the most widely used sludge treatment method • Overall, the process converts about 40% to 60% of the organic solids to methane (CH4) and carbon dioxide (CO2) • The residual organic matter is chemically stable, nearly odorless, and contains significantly reduced levels of pathogens • The suspended solids are also more easily separated from water relative to the incoming sludge or aerobically treated sludge (such as in outdoor pond) • The treatment of wastewater sludge, from both primary and secondary treatment steps, consists of two main phases • In the 1st step, all incoming flows of sludge are combined, and the mixture is heated to a mild temperature (about body temperature) to accelerate biological conversion. The residence time here ranges from 10 to 20 days • In the 2nd tank, the mixture is allowed to undergo further digestion. There is no longer active mixing in order to promote separation, and there is no need of heating as the process generates its own heat • In further processes the settled sludge is dewatered and thickened. The goal is to separate as much water as possible to decrease the volume of material. Finally, a phase known as sludge stabilization reduces the level of pathogens in the residual solids, eliminates offensive odors, and reduces the potential for putrefaction

Sources: Dartmouth

44

GREAT LAWRENCE SANITARY DISTRICT (GLSD), MASSACHUSETTS & NEW HAMPSHIRE

• GLSD serves the following localities: Lawrence, Andover, Methuen, North Andover and Dracut, Mass., and Salem, N.H.

• GLSD’s treatment facility is capable of processing up to 52 million gal per day (mgd) of wastewater, with the average daily flow typically at 31 mgd

• The treatment system includes primary sedimentation, biological oxidation, secondary clarification and treated effluent chlorination

• Built in 2002, GLSD’s system features three anaerobic digesters for a total capacity of 4.2 million gal

• At GLSD, the biogas is used to maintain digester temperatures, and for onsite sludge drying and pelletizing

• Originally, the excess gas was captured and flared. Today, it is being used productively for building heating and domestic hot water

• The plant added two new boilers with dual-fuel burners capable of burning both biogas and natural gas

• These boilers use less water and produce steam more efficiently, largely replacing older ones that operate on natural gas and fuel oil

• Burning biogas for building heating and hot water makes use of an energy resource produced on site, while also reducing a dependence on fossil fuels

• Furthermore, the upgrades lead to a decrease in the flaring of biogas, which reduces greenhouse gas emissions

• The GLSD project is proving that wastewater treatment plants can be an untapped source of renewable energy. It also serves as an example of how being diverse with renewable energy projects can yield tremendous economic and environmental value. In a time of high energy costs and endless discussions regarding global warming, renewable energy success certainly is most welcome.

Sources: Water & Wastes Digest

45

Food & Beverage Industry

• Because of more stringent processing and sanitation requirements, the volume of food production and processing waste has increased in recent years • Disposal can be difficult for food processors due to rising hauling costs, as well as more stringent practices for animal feed and land application • At the same time, rising wastewater surcharges, utility costs and consumer pressure for products to be “green” are leading food processors to pursue on-site anaerobic treatment and energy recovery as an option for food waste • Another trend is forming partnerships with other food producers and/or with local municipalities to provide mutually beneficial codigestion opportunities, utilizing existing or new anaerobic digester infrastructure • Applications have been primarily limited to the following: High rate technologies for liquid carbohydrate wastes with low solids; Lagoon type applications for higher solid wastes where land is available; and medium rate conventional mixed technologies for wastes containing fats, oils, greases and moderate solids. The high-rate technologies are the most common application of the three listed • Europe has been practicing high solids digestion for years. The primary driver has been the ban on organic waste disposal to landfill and land application as well as preferential prices paid for the generated energy • Since it is not part of most food producers’ core business to own or operate AD facilities, opportunities are mostly being pursued as design-build- own-operate (DBOO) projects by developers, with the main goal of reducing overall operating costs to produce food • AD waste to energy projects are a great opportunity for the food and beverage market to recycle food waste to create renewable energy as well as other beneficial by-products – and to make their impact on the sustainability of the environment

Sources:Biocycle

46

HYDROTHANE + NORTH BRITISH DISTILLERY

• The North British Distillery Co Ltd. (NBD) worked with HydroThane UK to work on construction of high rate anaerobic digestion technology

• The installation was done in the Company’s central Edinburgh distillery site and comprised of 3 x 500 cu. m. ECSB reactors

• The project parameters and considerations were as follows: Feed post distillation liquor, COD Load 27,000Kg/day, Producing 450Nm3/hr biogas, Energy output >3 MW/hr total, 500kW CHP unit producing electricity, FIT’s income, Boiler producing steam at 10 barG, Reduction in gas and electricity imports and Increased spirit production

• Benefits for NBD were as follows:

• Reduced natural gas imports resulting in reduced energy costs

• Reduced carbon dioxide emissions by between 9,000 to 10,000 tonnes per year - reduced carbon footprint

• Reduced load on existing by-products evaporation process - increasing overall production capacity

• Reduced on-going water and effluent charges

Sources: Anaerobic Digestion and Bioresources Association

47

Dairy Industry

• Dairy industries discharge wastewater which is characterized by high chemical oxygen demand, biological oxygen demand, nutrients, and organic and inorganic contents. Such wastewaters, if discharged without proper treatment, severely pollute receiving water bodies • For treatment of dairy waste water, several physical, chemical and biological methods are available. However, dairy waste responds best to the biological treatment • The dairy wastewater consists of high organic matters, mainly Lactose, fat and protein. A suitable environment for Lactobacillus species is formed due to fortified nutrients in cheese whey which is useful in converting organic sources into methane via anaerobic process • Anaerobic treatment process is an appropriate technique for the bioconversion of dairy wastewater into biogas

Sources:International Journal of Applied Environmental Sciences

48

ANAEROBIC DIGESTER AT SPRING VALLEY DAIRY

• Traditionally, manure generated at Spring Valley Dairy was stored in a concrete manure storage pit and spread on crop fields. However, this manure management practice can potentially cause pollution to water and air, including water quality problems, dust, smog, greenhouse gases (methane), and odors • Faced with the potential of increasing federal and state regulations on animal waste, Spring Valley Dairy looked for alternative practices. The search quickly landed on anaerobic digestion technology • The digester system at Spring Valley Dairy is composed of several subsystem: Manure collection, Activation system, Covered manure storage, Engine generator set and Flare • With 236 animals on the farm, the manure production is about 3,400 gallons per day. The manure utilizes gravity to flow from the barn collection system to the manure pit, from which it is pumped into the activation system • These consist of two seed digesters with a capacity of 1,000 gallons each. The converted manure storage pit has a capacity of 300,000 gallons. A flexible, impermeable cover added to the top of the pit traps the biogas

• The retention time is 20 days for the activation digesters and 90 days for the manure storage pit

• Based on the cost-benefit analysis, the annual net cost is about $22.93/cow/year for odor control and waste stabilization

• Since the installation of the anaerobic digester system on Spring Valley Dairy, the odor from manure handling and spreading has been greatly reduced. The nutrients in manure are also controlled and the pathogens are likely also reduced

Sources: CORNELL

49

Pharmaceutical Industry

• Effluents from manufacturing operations in the pharmaceutical industry, such as antibiotic formulation, usually contain recalcitrant compounds • An approach towards appropriate technology for the treatment of pharmaceutical wastewaters has become imperative due to strict water quality legislation for environmental protection • Typically, pharmaceutical wastewater is characterized by high chemical oxygen demand (COD) concentration, and some pharmaceutical wastewaters can have COD as high as 80,000 mg.L -1 • Due to high organic content, anaerobic technology is a promising alternative for pharmaceutical wastewater treatment

Sources:International Journal of Chemical Engineering and Applications, Vol. 2, No. 1

50

ADI SYSTEMS + ABBOTT LABORATORIES

• Abbott Laboratories is an American pharmaceuticals and health care products company headquartered in North Chicago, Illinois, USA. The company operates in over 130 countries worldwide • Abbott Laboratories needed to investigate the anaerobic treatability of its plant’s bacillus thuringiensis (BT) and fermentation wastewater. ADI Systems was commissioned to carry out a pilot study on the wastewater generated at its pharmaceutical operation • ADI Systems’ pilot study was such a success, it led to the design and construction of a full-scale low-rate anaerobic ADI-BVF® system for Abbott Laboratories

• Results:

• System is simple to operate, cost-effective, and most importantly, provides reliable pretreatment of this difficult-to-digest pharmaceutical wastewater • The anticipated savings in sludge handling and disposal costs was a major driving force in the decision to choose ADI Systems’ technology

• The floating cover on each of the BVF reactors not only collects valuable biogas, but also helps control odors and temperature

• The biogas produced is used in plant boilers, helping to save on heating costs

Sources: Evoqua/ADI Systems

51

Chemical Industry

• During the last two decades large scale environmental initiatives have taken place in Europe and the United States, these have resulted in strict environmental regulations on the industrial emissions for the chemical industry • Chemical industrial wastewaters usually contain organic and inorganic matter in varying concentrations. Many materials in the chemical industry are toxic, mutagenic, carcinogenic or simply almost non-biodegradable. This means that the production wastewater also contains a wide range of substances that cannot be easily degraded • Anaerobic processes have higher capital and operating expenses than aerobic processes because the anaerobic systems must be closed and heated. Thus, anaerobic bioprocesses for treatment of hazardous wastewater streams are typically limited to treatment of low-flow-rate streams such as industrial effluent • Anaerobic organisms have recently been shown to be responsible for a number of reductive reaction processes that could have a significant impact on the treatment of certain classes of hazardous compounds. In particular, anaerobic organism have been shown to be capable of reductively dehalogenating a number of toxic compounds, such as chlorinated aromatics, that are very recalcitrant to aerobic degradation • Both aerobic and anaerobic treatment systems are feasible to treat wastewater from all types of industrial effluents. However, a combination using an anaerobic process followed by an aerobic treatment system is a better option, as it can make use of the advantages of both the treatment processes. Those hybrid systems produce a high removal of toxic pollutants

52

Sources: Awaleh MO, Soubaneh YD (2014) Waste Water Treatment in Chemical Industries: The Concept and Current Technologies

ADI SYSTEMS + TAE KWANG POLYESTER PLANT IN KOREA

• The Tae Kwang plant had an activated sludge system which was not meeting performance expectations due to overloading

• To overcome this, Tae Kwang investigated separating out the high-strength ethylene glycol waste stream and pretreating it anaerobically to reduce the load on the activated sludge system

• A successful in-house pilot study confirmed the anaerobic treatability of the ethylene glycol waste stream

• ADI was selected for the project

• Results:

• The compact design of the ADI® hybrid reactor allowed it to fit into the small space available at the waste treatment site in Ulsan City • The higher solids inventory in the hybrid reactor results in longer sludge retention times (SRTs). Longer SRTs improve the reactor’s ability to handle higher levels of toxic substances, shock loadings, and influent suspended solids

• The COD removal rate is estimated at 80%

Sources: Evoqua/ADI

53

REGULATIONS

Overview

History

Process

Technologies

AD Systems

O&M

Advantages

Drawbacks

Applications

Regulations

Market Overview Deals

The following section reproduces relevant content from the Global Methane Initiative’s Report titled “A Global Perspective of Anaerobic Digestion Policies and Incentives” published in November, 2014.

The full report can be found on Global Methane Initiative’s website and gives deep insight into the subject matter.

Please note that some of the regulations mentioned here may have undergone amendments since the original report was published.

Comprehensive Agriculture Policies And Regulations

“Most environmental and agricultural agencies have established a suite of agriculture and livestock production policies and regulations that include provisions for air emissions, water discharge and nutrient management. Anaerobic digestion projects are associated with several of these agricultural waste streams. Effective management of wastes generated from an AD project can eliminate direct waste discharges to the environment. Additionally, direct discharge of waste to the land, a water body or to the atmosphere usually requires the facility to meet permitting requirements and obtain permission from a regulatory agency”

Sources: A Global Perspective of Anaerobic Digestion Policies and Incentives - Global Methane Initiative

56

Policies and Regulations Globally

“Regulatory frameworks for agriculture and renewable energy are important factors that influence the adoption and implementation of anaerobic digesters as well as the availability of

specific feedstock materials. Well-developed regulatory and policy frameworks encourage owners and developers to implement renewable energy systems and, in the context of this

report, anaerobic digester systems in the agricultural sector. Interest in AD has increased globally as governments work to reduce greenhouse gas emissions and identify alternative

energy sources for growing populations.” - Global Methane Initiative

Sources: A Global Perspective of Anaerobic Digestion Policies and Incentives - Global Methane Initiative

57

Air Emissions From Farms

“Anaerobic digesters are not emissions-free. Digesters can generate air contaminants either directly via the digestion process, or indirectly via combustion of the gas generated

from the anaerobic digester. Air emissions can be discharged from flares, boilers or from cogeneration equipment, but these discharges can be managed with pollution control

devices. ”

Sources: A Global Perspective of Anaerobic Digestion Policies and Incentives - Global Methane Initiative

58

Water Emissions

“Agricultural operations; in particular, the animal wastes from livestock operations, are one of the leading contributors to water pollution. AD systems offer an effective means to manage animal wastes and the digestion process produces a digestate (liquid effluent) that can be used beneficially as fertilizer. However, the AD process also produces water emissions and if improperly managed, water discharge from a digester can impair groundwater and surface water quality ”

Sources: A Global Perspective of Anaerobic Digestion Policies and Incentives - Global Methane Initiative

59

Manure Storage

“More than half of the countries examined for this report have instituted manure management policies that outline the collection, storage and processing of livestock manure to prevent surface and groundwater contamination as well as reduce nuisance odors. Typically, manure is stored in various holding facilities on farms for several months and then used as fertilizer. By instituting policies on manure storage, countries encourage use of AD systems to mitigate odor while providing storage”

Sources: A Global Perspective of Anaerobic Digestion Policies and Incentives - Global Methane Initiative

60

Nutrient Management

“Nutrient management policies, in place in 16 out of 30 of the countries reviewed, encourage AD system implementation because the use of digestate as a fertilizer provides farmers with greater flexibility in regards to time and areas of application. Additionally, AD is effective at pathogen reduction, and applying digestate instead of untreated manure to agricultural fields reduces the likelihood of surface water pathogen contamination from the application of manure”

Sources: A Global Perspective of Anaerobic Digestion Policies and Incentives - Global Methane Initiative

61

Renewable Energy-Related Policies And Regulations

“Countries typically regulate energy production through a collection of statues, regulations, polices and common law. Many countries have developed or are starting to develop national

policies or laws that specifically address renewable energy sources. Most renewable energy regulations focus on solar power, wind power, hydropower and power from biomass (which

includes AD).”

Sources: A Global Perspective of Anaerobic Digestion Policies and Incentives - Global Methane Initiative

62

Country Level Energy Planning

“Comprehensive and holistic ways of planning and implementing energy actions at the national level have been developed for many countries. Action plans in several countries include a commitment to increase energy output from livestock manure processed at AD facilities, while other countries discuss energy planning in terms of biogas.”

Sources: A Global Perspective of Anaerobic Digestion Policies and Incentives - Global Methane Initiative

63

Countries That Use Incentive to Encourage AD

Sources: A Global Perspective of Anaerobic Digestion Policies and Incentives - Global Methane Initiative

64

MARKET OVERVIEW

Overview

History

Process

Technologies

AD Systems

O&M

Advantages

Drawbacks

Applications

Regulations

Market Overview Deals

Market Overview

The growth in the global AD disinfection market is anticipated to be driven primarily by the regulatory environment

Global Market for AD Equipment

11

95 % of the 2022 market size will be attributable to landfill gas, agriculture, food and municipal wastes

$10.10bn

8.25

$6.10bn

5.5

11.4 % CAGR through 2022 will make wastewater/sludge and industrial applications the highest growth sub-segment in the global AD markets

2.75

0

2017

2022

Sources: bcc research

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