FACULTY OF COMPUTING, ENGINEERING and SCIENCE

Final mark awarded:_____

Assessment Cover Sheet and Feedback Form 2014/15

Module Code:RE4S008

Module Title:Anaerobic Treatment Processes

Module Lecturer:Dr. Iain Michie

Assessment Title and Tasks: Mini project and poster presentation

Assessment No. 3e.g. 1 of 3

No. of pages submitted in total including this page: Completed by student

Word Count of submission(if applicable): Completed by student

Date Set:9/10/2014

Submission Date: 26/03/2015

Return Date:23/04/2015

Part A: Record of Submission (to be completed by Student)

Extenuating CircumstancesIf there are any exceptional circumstances that may have affected your ability to undertake or submit this assignment, make sure you contact the Advice Centre on your campus prior to your submission deadline.

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Plagiarism and Unfair Practice Declaration: By submitting this assessment, you declare that it is your own work and that the sources of information and material you have used (including the internet) have been fully identified and properly acknowledged as required1. Additionally, the work presented has not been submitted for any other assessment. You also understand that the Faculty reserves the right to investigate allegations of plagiarism or unfair practice which, if proven, could result in a fail in this assessment and may affect your progress.

Details of Submission: Note that all work handed in after the submission date and within 5 working days will be capped at 40%2. No marks will be awarded if the assessment is submitted after the late submission date unless extenuating circumstances are applied for and accepted (Advice Centre to be consulted).Work should be submitted as detailed in your student handbook. You are responsible for checking the method of submission.

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IT IS YOUR RESPONSIBILITY TO KEEP A RECORD OF ALL WORK SUBMITTED

Part B: Marking and Assessment(to be completed by Module Lecturer)

This assignment will be marked out of 100%

This assignment contributes to 50% of the total module marks.

This assignment is non- bonded. Details :

Assignment Title and Tasks: : Individual Mini-Project and Presentation ‘Challenges in the implementation of integrated anaerobic processes for waste treatment’

Format for the report1. Summary2. Introduction to the anaerobic treatment processes

a. Critically review present status of technical development b. Field applications (if existent): characteristics and status c. Literature related to environmental and economic benefits of each process

3. Selection of one main combination for the integration of these processes for waste and wastewater treatment and bioenergy recovery

a. Present a case for the integration and the respective system flow diagramb. Evaluate the potential for the integrated process related to technical, economic and

environmental performancesc. Evaluate the challenges that may occur in delivering such integrated anaerobic treatment

systemd. Discuss possible improvements for the integrated anaerobic treatment systeme. Discuss the needs to integrate with other complimentary processes in order to maximise

efficiencies and quality outputs 4. Conclusions5. References

Important note: If biogas is produced from your selected process, it is compulsory to include biogas upgrading as a technique for biomethane production for gas grid injection or for transport fuel.

It is anticipated that in addition to the materials provided in the lectures, you will be required to research much more widely available literature. Reviewing a number of journal publications is certainly be a requirement.

The report should not have more than 4500 words (and accounts for 30% of the mark). Please submit the report on the 26th March 2015. You will also be required to do a presentation for 20 mins using a powerpoint slide with the main information that you have included in your report. Questions from the lecturers assessing the presentation will follow at the end of your presentation. The presentation will take place on 26th March 2015 during the normal scheduled class and accounts for 20% of the mark.

This individual mini project report and poster presentation contributes 50% to the overall mark for this module.

ContactPlease contact Dr. Iain Michie if you need further assistance and advice related to this individual mini projectEmail: iain.michie@southwales.ac.uk

Learning Outcomes to be assessed (as specified in the validated module descriptor http://icis.glam.ac.uk): This assignment addresses the following learning outcome(s) of the module:

1. Demonstrate a sound knowledge of scientific and technical principles of the anaerobic treatment processes

2. Critically review the factors that influence process selection, reactor design and operation for

each anaerobic treatment process 3. Ability to specify and conduct an effective process monitoring regime 4. Evaluate the needs to integrate an anaerobic treatment process with other complimentary ones

in order to maximise efficiencies and quality outputs 5. Critically evaluate the environmental and economic benefits and impacts of utilising each

anaerobic treatment process in terms of treatment efficiency, energy savings or net bioenergy yield as well as production of other products from process intermediates or from digestate

Grading Criteria:Marks Available

Marks Awarded

Report:

1. Quality of summary and conclusions 15

2. Structure and presentation of the report 15

2. Quality of referencing 10

4. Critically review individual process technologies (applications, status, benefits and challenges)

30

5. Evaluation of the system integration 30

Poster presentation:

1.  Quality of the structure and presentation of the poster 25

2.  Relevance of contents of the poster 25

3. Clarity in the presentation and ability of convey the message within the time allocated

25

4. Ability to answer questions 25

Feedback/feed-forward (linked to assessment criteria): Areas where you have done well:

Feedback from this assessment to help you to improve future assessments:

Other comments

Mark: Marker’s Signature: Date:

Work on this module has been marked, double marked/moderated in line with USW procedures.

Provisional mark only: subject to change and/or confirmation by the Assessment Board

Part C: Reflections on Assessment(to be completed by student – optional)

Use of previous feedback:

In this assessment, I have taken/took note of the following points in feedback on previous work:

Please indicate which of the following you feel/felt applies/applied to your submitted work

A reasonable attempt. I could have developed some of thesections further.

A good attempt, displaying my understanding and learning, with analysis in some parts.

A very good attempt. The work demonstrates my clear understanding of the learning supported by relevant literature and scholarly work with good analysis and evaluation.

An excellent attempt, with clear application of literature andscholarly work, demonstrating significant analysis and evaluation.

What I found most difficult about this assessment:

The areas where I would value/would have valued feedback:

Challenges in the implementation of integrated anaerobic processes for waste

treatment

Radu Ivanescu (14089637)Anaerobic treatment processRenewable energy and Resource management

Table of content

1. Summary2. Introduction to the anaerobic treatment processes

a. Critically review present status of technical development b. Field applications: characteristics and status c. Environmental and economic benefits of each process

3. Integration of the previous processes for waste and wastewater treatment and bioenergy recovery

a. Integration and the respective system flow diagramb. Evaluation of the potential integrated process related to technical, economic and

environmental performancesc. Evaluation of the challenges that may occur in delivering such integrated anaerobic

treatment systemd. Discussion on possible improvements for the integrated anaerobic treatment systeme. Discussion of the needs to integrate with other complimentary processes in order to

maximise efficiencies and quality outputs 4. Conclusions5. References4. Conclusions5. References

1. Summary

The following report focuses on the waste treatment of a dairy farm taking in consideration current technical development and future anaerobic trend technology. Mainstream anaerobic treatment processes are based on the conversion of organic matter in the absence of oxygen, by microorganisms, into biogas. This kind of process is energy-efficient and is mainly used to treat warm industrial wastewaters with a high concentration of biodegradable organic matter (measured as BOD, COD and/or TSS). Anaerobic biological decomposition of waste use substantially less energy, require a low amount of chemicals and have low sludge handling costs compared to other aerobic treatment processes. Also, the biogas resulted from the process is a renewable source of energy that can be a good replacement for natural gas or can be used to generate electricity.

2. Introduction to the anaerobic treatment processes

a. Critically review present status of technical development

For the following report a dairy farm was taken in consideration. The actual development of the waste treatment consists of an Anaerobic Digester where the feedstock is treated. The reactor type is ADI-BVF Anaerobic Reactor [1]. Due to its low-rate anaerobic process and the high hydraulic retention time the system provides stability and efficiency of the process. The waste of the sludge is thus minimized and can be used as landfill once or twice per year.

The design of the reactor enables the biological solids to settle into the sludge bed. The reactor also contains a gas-liquid-solid separator that produce a low effluent TSS. The current configuration of the reactor is Type L, a partially in-ground concrete earthen basin. Waste pre-treatment is not required as the reactor has a coarse screening and a wide operating temperature rate (20-400C).

The feedstock is inserted beneath the sludge bed via an influent distribution system. An adjustable pumping schedule dictates the way that the feed mixes with the recycled sludge, thus, by the uprising of the wastewater through the sludge bed results an enhanced contact between the two of them. Thereby under the microbial decomposition of the biomass, BOD, COD, TSS and FOG are converted into biogas.

The biogas is collected by a membrane system after it rises through the liquid. The collected gas is extracted with the help of the negative pressure created by external blowers, stopping the escape of the gas or odours in the environment. The membrane system collects and stores the biogas, minimizes heat loss and has the potential for rainwater collection. The membrane has a higher resistance to corrosion than concrete or steel, is UV resistant and provides easy maintenance without the need of pausing the process.

The biogas, currently is used to power a CHP system in order to generate electricity for the blowers used at the digester and also to provide heat for the digester. The waste sludge that results from the reactor goes into a separator. Here, after presses are used, the solid content is used for animal bedding or for soil amendment or peat moss replacing. The remaining liquid is decanted in a lagoon. The actual configuration of the waste treatment facility is shown in Figure 1.

Figure 1. Current configuration of dairy waste treatment

b. Field applications: characteristics and status

Additional technologies can be employed in order to make the feedstock treatment more effective. Besides the currently used processes that offer animal bedding and soil amendment as final products, other benefits can arise from using a gas scrubber, basins for nutrient recovery and a pyrolysis system.

GAS SCRUBBER

A cost-effective method of upgrading the biogas could provide dairy farmers the means to complement or replace the electrical power used from the grid. Also, because of the similar proprieties between biogas and natural gas, biogas driven cars and buses can refuel from it.

The methods that can be used for gas scrubbing and are commercial available are as follows:

Water and Polyethylene Glycol Scrubbing – process used to remove CO2 and H2S from biogas. The process is purely physical as CO2 and H2S are more soluble than methane. The flow chart for this technology is presented in Figure 2.

Figure 2. Flow chart of Water and Polyethylene Glycol scrubbing process

Chemical Absorption – this process needs a relatively high energy input in order to break the bonds created between the solute and the solvent in order to regenerate the solvent. The H2S is completely removed from the biogas using this technique. A flow chart of the process is represented in Figure 3.

Figure 3. Flow chart of chemical absorption process.

Pressure swing adsorption – with the use of different adsorbent materials, a specific gas can be separated from a mixture of gases. The process takes place by changing the pressure of the gas mix, first high pressure in order to have an adsorption of the desired gas, then low pressure to desorb the adsorbent material.(Cavenati et al., 2005) [2]. The flow chart diagram is represented in Figure 4.

Figure 4. Flow chart of Pressure-swing adsorption

Membrane separation – a thin membrane allows some components of the raw gas to pass while others are retained. Typical operating pressures are between 25-40 bars. The purity of the methane yield can be enhanced by adding more membrane modules, but a drawback will be felt in the quantity of methane produced. The flow chart in Figure 5 represents the membrane purification process.

Figure 5. Flow chart of membrane biogas purification process.

Cryogenic separation – this process is based on the fact that CO2, H2S and all of the other components can be separated from the CH4 because of different liquefaction point. The process takes place at low temperature (-100oC) and high pressures (40 bars). The schematics of the cryogenic separation is represented in Figure 6.

Figure 6. Schematic of cryogenic separation

PYROLYSIS

Pyrolysis is a thermo-chemical process by which organic material is decomposed at high temperatures (200-20000C) in the absence of oxygen. Because of the very high range of temperatures used, a large variety of by-products can be obtained. The common pyrolysis of sugar in bakery processes needs more than 1700C, most of agricultural waste pyrolysis processes operating temperature is between 450-5500C, and the carbon fibre is produced by pyrolysis of carbon fibres filaments at temperatures between 1500-27500C.

As an endothermic process it requires a source of heat. The following methods are viable heat providers:

By partial combustion using air injection. The biomass products result in low quality by-products.

Using a hot gas to provide direct heat transfer. It is preferable to recycle the same gas that is produced.

Using exchange surfaces for indirect heat transfer. It is a challenge to obtain a proper transfer on both sides of the surface.

Using an effective but complex technology based on direct heat transfer made by circulating solids between a burner and a pyrolysis reactor.

Table 1 shows a list of Pyrolysis Reactors used today

Table 1. Types of Pyrolysis Reactors

c. Environmental and economic benefits of each process

The biogas resulted after digestion can be used as a fuel. A refuelling stations for cars with on-site production can be implemented with the help of a gas scrubber. The role of a gas scrubber is to obtain high quality methane by removing acidic impurities from the biogas. According to Zhao et al. (2010) [3] the following options are available with an estimate cost made by De Hullu et al. (2008) [4] when talking about gas scrubbing:

Water and Polyethylene Glycol Scrubbing (0.13€/Nm3 biogas) – the advantages related with this process are the cheap means and easy to procure solvent, water or glycol; the mean disadvantage is represented by the high quantities of water needed and that the H2S removal is limited by the corrosive pH given by the CO2 in the solution.

Chemical Absorption (0.17€/Nm3 biogas) – it has a CO2 residue waste stream released into the atmosphere. A liquid water phase with a catalyst is needed in the absorption process.

Pressure Swing Adsorption (0.40€/Nm3 biogas) – the biogas yielded is of a high purity CH4 more than 97%. The CH4 stream can lead to a gas engine connected to a generator or can be recycled to increase the CH4 production.

Membrane (0.12€/Nm3 biogas) – it is a complex process that implies two separation techniques; the first process is a gas separation made at high pressure, in three stages, with a yield of 96% purity CH4. The second process is made through gas-

liquid adsorption. Although it has a low price, high concentration CH4 production and low maintenance cost of the system itself, the low yield and the potential often replacement of the membrane can influence the price estimation.

Cryogenic Separation (0.44€/Nm3 biogas) – environmentally friendly method due to its lack of chemical demand. Very energy demanding process that has a waste stream of high quantities of CO2 with traces of CH4 and H2S.

3. Integration of previous processes for waste and wastewater treatment and bioenergy recovery

a. Integration of the system and system flow diagram

For the current system the following upgrades have been taken in consideration:

A Biogas Scrubber based on Pressure Swing Adsorption technology; although the implementing cost of this technology is high, the investment is worth making due to the simplicity of the design, the high purity CH4 yielded and the capacity to fuel vehicles, engines connected to generators and gas storage and gas recirculation capacity.

A nutrient recovery stage, where two settling basins recover Phosphate and Nitrate from the liquid waste resulted from the separator.

Future development of a Pyrolysis system can be implemented. Although the technology is not new, its usage on dairy feedstock is not yet been developed at commercial stage. The advantage of a Pyrolysis system would be reflected in more biogas fuel yielding and can be correlated with alternate renewables and can result even in clean, drinkable water if needed.

The system flow diagram is represented in Figure 6.

Figure 6. System flow diagram

b. Evaluation of the potential integrated process related to technical, economic and environmental performances

All of the upgrade processes

c. Evaluation of the challenges that may occur in delivering such integrated anaerobic treatment system

d. Discussion on possible improvements for the integrated anaerobic treatment system

e. Discussion of the needs to integrate with other complimentary processes in order to maximise efficiencies and quality outputs

4. Conclusions5. References

1. Ringer M, V Putsche, and J Scahill. 2006. Large-Scale Pyrolysis Oil Production: A Technology Assessment and Economic Analysis. NREL/TP-510-37779. National Renewable Energy Laboratory, Golden, Colorado.

2. Pytlar T.S., 2010, Status of Existing Biomass Gasification and Pyrolysis Facilities in North America. Proceedings of the 18th Annual North American Waste-to-Energy Conference, Orlando, FL:ASME Technical Publishing

3. Son, Y.I., S.J. Yoon, Y.K. Kim, and J.G. Lee, 2005, gasification and power generation characteristics of woody biomass utilising a downdraft gasifier. Biomass and Bioenergy 35(10):4215-4220.

4. http://www.adisystemsinc.com/pdfs/ADI-BVF_Brochure.pdf 5. Cavenati, S., Grande, C.A., Rodrigues, A.E., 2005. Upgrade of methane from

landfill gas by pressure swing adsorption. Energy & Fuels, 19, 2545-2555.6. Q. Zhao, E. Leonhardt, C. MacConnell, C. Frear and S. Chen, (2010), Purification

Technologies for Biogas Generated by Anaerobic Digestion, CSANR Research Report 2010

7. De Hullu, J., Maassen, J.I.W., van Meel, P.A., Shazad, S., Vaessen, J.M.P. (2008). Comparing different biogas upgrading techniques. Eindhoven University of Technology, Netherlands.