Difference between revisions of "Stockpile"

Latest revision as of 23:53, 16 July 2011

Change happens[edit]

Jeanette A. Brown, testimony to Congress (2/4/2009), “Energy Efficiency and Energy Independence for Sustainable Wastewater Treatment” “The landscape is changing as technologies and concepts are being developed to allow plants to be energy independent or even net energy producers. This evolution in thinking moves wastewater treatment plants from being major energy consumers to net energy producers and represents a paradigm shift in the sector.”

background[edit]

Nel corso del 2007 è stato raggiunto tra l’AATO1, la Viareggio Patrimonio Srl e Gaia Spa (delibera AATO1 n. 53 del 25.09.2007) un accordo finalizzato allo scorporo della linea fanghi dell’impianto di depurazione dalle infrastrutture del Servizio Idrico Integrato, in modo tale da consentire alla Viareggio Patrimonio Srl di riprendere possesso della linea fanghi, ai fini della sperimentazione sulla FORSU già da tempo operata con le modalità tecniche e gestionali in essere ai fini della realizzazione del progetto inerente all’attività di codigestione anaerobica di fanghi e frazione organica da RSU proveniente da raccolta differenziata per la produzione di biogas. Ciò come previsto dal contratto di J. Venture in essere <ref name="poa2009"> VIAREGGIO PATRIMONIO S.R.L. P.O.A. 2009, poa2009_struttura </ref>

Intended Audience[edit]

Decision makers with significant technical and/or finance background; for example:

• Municipal Managers
• Engineers
• Finance Managers
• Wastewater Treatment Plant Managers and Operators

activated sludge codigestion ratio[edit]

Co-digestion of the organic fraction of municipal solid waste with primary sludge at a municipal wastewater treatment plant in Turkey

Co-digestion of the organic fraction of municipal solid waste (OFMSW) and sewage sludge may be an attractive alternative for sustainable management of two separate waste streams produced in large amounts in all countries. This study evaluates calculation-based results of an anaerobic co-digestion process for primary sludge (PS) together with the OFMSW. The calculations were carried out for the anaerobic digester of Kayseri municipal wastewater treatment plant (in Turkey) presently digesting only PS. Two alternatives were proposed using different solid waste contents in co-digesters. For achieving the optimal solids content, some treated wastewater should be recycled to the inlet of the digesters. The municipal solid waste collection method characterized as mechanically sorted (MS-OFMSW; Option 1) is evaluated as well as a source sorted (SS-OFMSW) alternative (Option 2). Utilizing the energy produced by the existing sludge digester, only 30% of the internal energy demand at the wastewater treatment plant can be covered. The aim of this study is to evaluate how energy production would be increased by co-digestion of OFMSW and PS. The best operational condition considering organic loading rate, hydraulic retention time and energy generation could be attained at 10% digester solids content for both options. According to Option 1, almost 77% of the energy demand could be covered by co-digestion of MS-OFMSW and PS. Results indicated that almost 100% energy coverage can be obtained when co-digestion (Option 2) was performed according to SS-OFMSW and PS.

• BIOCEL (batch-wise dry anaerobic digestion);
• DRANCO (dry anaerobic composting process employing a one-stage anaerobic digestion system, which is followed by a short aerobic maturation phase);
• Valorga (one-stage dry anaerobic digestion process which uses a vertical cylindrical reactor which can be operated at both mesophilic and thermophilic temperature);
• KOMPOGAS (one-stage dry anaerobic digestion process; the fermentation process takes place in a horizontal plug-flow reactor at thermophilic temperature);
• Waasa (wet, one-stage anaerobic digestion system and is operated at both, mesophilic and termophilic temperatures);
• BTA (consists of two major phases: hydro-mechanical pre-treatment and anaerobic digestion processes);
• Schwarting-Uhde (two-stage wet anaerobic digestion process which is performed in a series of two vertical plug-flow reactors);
• Linde-BRV (two-stage dry anaerobic digestion).

Waste characteristics The organic fraction of municipal solid waste is rather a heterogeneous substrate and the biogas yield in the AD treatment of OFMSW is dependent not only on the process configuration, but also on the waste characteristics. The content of lignocellulose, for instance, determines the biogas potential. The C:N ratio is an important parameter in estimating nutrient deficiency and ammonia inhibition and the particle size may influence the degradation rate of the waste. The waste characteristics are highly dependent on the collection system. Source sorting of MSW generally provides OFMSW of higher quality, in terms of smaller quantities of non- biodegradable contaminants like plastics. Mechanically separated OFMSW is more contaminated, which leads to persistent handling problems and lower acceptability of the effluent product of the treatment process used as fertilizer on agricultural land (Braber, 1995).

Particle size Generally, the particle size of solids has a significant influence on the biodegradation rate, since the surface area to which enzymatic attack is possible, increases with a smaller particle size. Accordingly, Kayhanian and Hardy (1994) identified particle size as an important parameter in the performance of the high-solids anaerobic digestion process for OFMSW. Their results indicated that the rate of methane gas production was inversely proportional to the average feedstock particle size. Furthermore, it was concluded that reducing the particle size might also reduce material handling difficulties. However, there are several inconsistencies in the literature, as to whether particle size reduction is beneficial. Depending on the moisture content, shredding of the waste can lead to compaction of the waste and a lower optimal moisture content (Hamzawi et al., 1999).

Anaerobic digestion of the organic fraction of municipal solid waste with recirculation of process water Hinrich Hartmann

“ The key is to purchase a trusted technology at the right price and to also allocate risks and responsibilities correctly.”

Councils should understand that their overall waste strategy is so much more important than the ‘box’ (technology) that processes the waste. Taking the time to examine your goals, and options for bins, transport, collection, alliances with other councils, end markets and how to finance it all, are some key considerations. As a basic rule of thumb, when considering an AWT, councils should inspect a reference plant operated by the same company; with the same in-feed material; at the same scale; and one that has been operating profitably for a minimum of two to three years. Another thing to keep in mind: councils should not think they can insulate themselves from technological and financial risk with a tight contract. Master-servant contracts won’t protect them, when and if, the plant fails. We have seen councils paying a lot more to rescue underperforming technologies in the past 10 years, in spite of ‘tight’ contracts. Having said all that, AWT has a very strong future. The market is maturing, buyers are becoming savvier and market participants are asking the right kinds of questions. The questions councils should be asking themselves are as follows: What do we really want to achieve – diversion, cost, emissions etc? How much are we prepared to pay? What is our risk appetite? What is our technology and contractual risk? What is our unavoidable risk? A number of factors are all driving the market for AWT forward, including government policy, carbon pricing, environmental concerns and technology improvements. This could result in AWT representing up to 15% of the market by 2020. The likely winners are composting (particularly source-separated organics or SSO), SSO anaerobic digestion, SSO pyrolysis and specific stream incineration.

TechnologyRisk_Issue41.April2011.InsideWaste.pdf

Food waste is more readily biodegradable and requires less residence time and digester volume than municipal biosolids.

SUMMARY: During 2009, a research and experimentation activity started with the aim of developing a technology for the co-digestion of OFMSW and topinambur stalks and subsequently demonstrate the technical - economic feasibility of this innovative mixture of raw materials for the production of energy and biofuels (bio-methane) at the Bracciano Cupinoro landfill.

AN INNOVATIVE PROJECT FOR THE PRODUCTION OF BIOGAS BY CO- DIGESTION OF THE OFMSW AND TOPINAMBUR AT THE LANDFILL OF CUPINORO (BRACCIANO, RM) V. PIGNATELLI*, V. ALFANO*, A. CORRENTI* AND A. FARNETI*

• ENEA - Italian National Agency for New Technologies, Energy and Sustainable

Economic Development. Via Anguillarese, 301 - 00123 - Rome, Italy

above and below screen fraction[edit]

Mesophilic Anaerobic Digestion of Mechanically Sorted Organic Fraction of Municipal Solid Waste

The mechanically sorted organic fraction of municipal solid waste (MS-OFMSW) from Wuzhou was divided into above screen fraction (AS-MS-OFMSW) and below screen fraction (BS-MS-OFMSW). The experimental results showed that, the volatile solid (VS) of AS-MS-OFMSW was 28.6% with biodegradable VS of 82.5%. A VS removal of 19.7% and a methane yield of 93.1 L/kgVS were obtained in mesophilic digestion with TSr 20%. In case of BS-MS-OFMSW, the VS content was 17.1%. The methane yield and VS removal were 37.3 L/kgVS and 9.5% respectively. The nutrition content in solid fraction of digested residue satisfied the requirement of Chinese standards. However, four heavy metal contents (Cr, Cd, Pb and Ni) were beyond the allowed levels.

Li Dong Yuan Zhenhong Sun Yongming Guangzhou Inst. of Energy Conversion (GIEC), Chinese Acad. of Sci. (CAS), Guangzhou, China

This paper appears in: Bioinformatics and Biomedical Engineering (iCBBE), 2010 4th International Conference on Issue Date: 18-20 June 2010 On page(s): 1 - 4 Location: Chengdu ISSN: 2151-7614 Print ISBN: 978-1-4244-4712-1 INSPEC Accession Number: 11495776 Digital Object Identifier: 10.1109/ICBBE.2010.5517914 Date of Current Version: 23 July 2010

Target EU Legislation (old, TBU)[edit]

Climate Change COM (2000) 88 final - "Towards a European Climate Change Programme (ECCP)" (08.03.00) Kyoto Protocol to the United Nations Framework Convention on Climate Change - Declaration Officia ... Waste  Directive 86/278/EEC -"Protection of the environment and in particular of the soil where sewage s ... Directive 1999/31/EC -"Landfill of waste" (26.04.99) Water Directive 91/271/EC - "Urban waste water treatment" (21.05.91)

ISWA 2012 Florence[edit]

ATIA-ISWA ITALIA, the National Member of ISWA for Italy, is proud to organise the World Solid Waste Congress 2012 in the City of Florence, from Monday September 17th to Wednesday September 19th 2012.

During the three days of this Congress you can meet academics presenting cutting edge research; scientists; government administrators and decision makers; representatives of the world’s largest companies in the waste sector, and many other practitioners too from small and medium enterprises. Florence 2012: where else in the world can you network with these people in such a short time?

The Congress location is at the Palazzo dei Congressi adjacent to the Santa Maria Novella mainline railway station in the City center.

ATIA-ISWA ITALIA is also organising a series of events from 2010 to 2012 in Italy leading to the main Congress of 2012.

This beautiful city will also host a series of memorable social events in historic palaces and buildings in the city centre making your stay an unforgettable moment.

Congress fees and registration forms will be published here later in 2011 and the organisers will endeavor to ensure the lowest possible fees to enable access to the widest possible audience worldwide.

The Florence World Solid Waste Congress 2012 is an event you cannot miss.

problem definition[edit]

http://www.jgpress.com/archives/_free/001883.html

Codigestion maximizes energy production in an AD plant by adding substrates that produce much more biogas per unit mass than the base substrate.

Dennis Totzke

CODIGESTION refers to processing multiple biodegradable substrates (feedstocks) in an anaerobic digestion (AD) system. A more contemporary definition refers to the digestion of a combination of select biodegradable feedstocks with a base substrate that an AD system was designed to handle. The intent is to maximize the production of biogas (i.e., renewable energy) by adding substrates that produce much more biogas per unit mass than the base substrate. Two readily available substrates — municipal biosolids and agricultural manure — are the base substrates most often utilized. Unfortunately, both biosolids and manure are near the bottom of the “biogas per unit mass” scale.

An existing AD plant with some associated infrastructure often can be used as is or with minor modifications to handle the codigestion substrate, thus minimizing capital expenditures. Codigestion systems can also function as regional digestion plants, helping to resolve waste issues for multiple generators. However, the benefits that can be realized from codigestion, as well as the potential pitfalls that can be encountered, need to be carefully evaluated. In the case of low-cost or free high-energy potential substrates, it pays to look the gift horse in the mouth.

One reason for the increased interest in codigestion is the creation of numerous opportunities for the use of biodegradable wastes due to the tremendous number of AD plants online and currently being constructed in the United States. Research by Applied Technologies has estimated that there are over 600 operating systems in the industrial and agricultural fields in the U.S. handling various industrial and agricultural wastes. Figure 1 illustrates the number of constructed installations and growth in the anaerobic digestion field. Information published in February 2009 by AgStar, a program jointly sponsored by the U.S. Environmental Protection Agency, Department of Agriculture and Department of Energy estimated that there were 125 farm-scale digesters operating at commercial livestock farms handling manure in the United States.

In the public sector, many publicly owned treatment works (POTW) have for years incorporated AD processes into their overall wastewater treatment schemes to handle primarily biosolids (waste sludge from municipal wastewater treatment plants). A 2004 USEPA national survey of POTWs with a hydraulic capacity greater than 5 mgd estimated that there were nearly 1,100, of which nearly 550 utilized AD systems to handle biosolids. In terms of a single state, a Wisconsin Focus on Energy study completed in January 2006 identified 85 digesters in Wisconsin at POTWs that handle primarily biosolids, 16 of which are of 5 mgd capacity or greater. The latter two groups of AD systems, those handling manure and biosolids, probably number over 1,000 nationwide and are responsible for providing most of today’s codigestion opportunities.

POTENTIAL SUBSTRATES Designers and operators of AD systems have a wide variety of potential substrates from which to choose when considering how to boost biogas production. In addition to the base substrate used, numerous wastes are available, many of which have been tested to benchmark fundamental characteristics. Table 1 provides a partial listing of substrates for which some biodegradability and/or biogas production data is available. Table 2 provides laboratory-scale methane yield data on a selection of substrates and the common base substrates of municipal biosolids and cattle manure. The information is provided in units of methane produced per unit dry mass (volatile solids, or VS) applied. It should be noted that data provided in the literature and from various system suppliers will be presented in many forms — biogas instead of methane, wet total solids (TS) instead of dry VS, applied versus removed substrate — requiring a great deal of evaluation before use in any comparative assessment. In addition, all substrates, e.g. food wastes, are not created equal; they possess different levels of protein, fat/oil/grease (FOG), and carbohydrates. Testing the specific waste stream is necessary to obtain a realistic idea of its biogas potential.

The variety of possible substrates and the variability in biogas potential can create some “selection” issues. However, quite often the overriding factor in the potential usefulness of many substrates is economic — the cost of obtaining, transporting and preprocessing the material to the point that it can be fed to an AD plant to obtain increased biogas production. Optimally, an AD facility should receive a tipping fee for handling the waste. Conversely, an AD facility may need to pay for and transport a codigestion substrate a long distance to the AD plant. These two scenarios bracket the range of possible economic outcomes for a codigestion application.

Unfortunately, when examining potential substrates for codigestion, most attention is paid to such characteristics as biodegradability (as measured by VS or COD destruction) and biogas production (as measured by cubic meters or cubic feet of biogas or methane per unit mass or volume applied). Other characteristics of critical importance are: Organic nitrogen; Presence of chemicals; Sulfur; Levels of K, N and other cations; pH and alkalinity; Phosphorus; Fat, oil and grease (FOG); and Gross solids.

These characteristics impact the operation and performance of an AD system. For example, knowing the level of organic nitrogen in a waste makes it possible to predict the amount of ammonia it will generate during anaerobic digestion, since nearly all organic nitrogen is converted to ammonia. One can then evaluate the impact of the ammonia on issues such as ultimate effluent discharge (e.g. discharge limits or surcharges), potential ammonia inhibition or toxicity to the anaerobic process, the economic viability of N recovery, etc.

Other characteristics can affect the choice of pretreatment process or AD technology. For example, the presence of straw, wood knots and plasticware might dictate the addition of a grinding or screening step upstream of the AD process. Similarly, high levels of FOG would favor use of an AD technology with good mixing versus those without (e.g., plug flow and anaerobic lagoon).

BLENDING AND FEEDING Once the base substrate and supplemental codigestion substrates have been identified and are ready to be fed to the AD system, care must be exercised in blending and feeding them to minimize process upsets. For optimum AD process performance when running a codigestion system, it is advised to follow these guidelines: 1) Test individual codigestate loads for characteristics of concern. At a minimum, test for COD, TS, VS, TKN and pH. If the quality of any load is suspect, segregate it and run a biomethane potential test on it. This is a laboratory test run in a sealed serum bottle with “standardized” anaerobic biomass and the substrate under investigation. The results provide an idea of the quantity and quality of biogas that can be produced. 2) Store various codigestates in separate mixed and heated tanks or areas. This minimizes downstream preparation time and allows more precise blending and more careful control of organic loading. 3) Develop a preferred feed ratio for the various substrates, making small changes to it as the availability of the various base substrates and/or codigestates changes. This reduces the chances of upsetting the anaerobic process through organic overloading. 4) Collect full-scale system data and use it to adjust feed ratios and digester operating parameters.

East Bay Municipal Utility District in Oakland, California has been operating a program for industrial and commercial organic wastes, preprocessing and feeding them to existing biosolids anaerobic digesters to boost biogas production. The Inland Empire Utilities District in Chino, California handles dairy cattle manure and food processing wastes in a thermophilic digestion system designed and constructed specifically for codigestion. A number of POTWs in California manage programs that accept FOG-type wastes and feed them to existing biosolids digesters.

In Wisconsin, the availability of dairy production wastes from a number of small dairy operations has helped develop codigestion. For years, the Madison Metropolitan Sewerage District accepted cheese whey from a local dairy and fed it directly to existing biosolids digesters. Similarly, POTWs in Beaver Dam, Sheboygan, South Milwaukee and Waupun have accepted dairy and/or other wastes and used them in existing biosolids digesters to boost biogas production. In a unique codigestion application, the Milwaukee Metropolitan Sewerage District has been handling spent deicing fluid from Mitchell International Airport at its South Shore treatment plant since 2000, codigesting it with biosolids.

Companies employ codigestion in the private sector as well. Unilever in Maryland has codigested ice cream novelty production wastewater and waste product anaerobically since 1991. Microgy has three thermophilic digesters in Wisconsin, handling dairy manure along with alcohol production wastes, glycerin, FOG and other wastes. More recently, the Crave Brothers Farm in Waupun, Wisconsin doubled the size of its AD system to handle additional dairy manure, milking parlor wastewater, cheese production wastewater and cheese whey.

REGULATORY IMPLICATIONS Rising interest in codigestion and an increasing number of operating plants are pushing the regulatory community with regards to permitting. POTWs that operate codigestion systems are perhaps best suited to deal with regulations, as they already have NPDES permits and most likely have dealt with air and solid waste permitting. Many POTWs are familiar with handling trucked-in wastes, such as septage, landfill leachate, grease-trap pumpout, etc., and have systems in place for record keeping, storage and handling. However, the potential impact of nutrients from codigestion of imported substrates may affect NPDES permit compliance efforts and needs to be carefully evaluated.

In the agricultural arena, CAFOs are strictly permitted and already have some authority to handle and store manure. However, the inclusion of nonmanure substrates can introduce solid waste and/or wastewater regulations. Codigestion of substrates with high nitrogen and/or phosphorus levels could impact comprehensive nutrient management plans. A presentation given by Joe Goicochea of the Ohio Environmental Protection Agency at the Biocycle 2008 Conference on Renewable Energy From Organics Recycling concluded that the classification and regulation of CAFO and on-farm codigestion systems varies significantly from state to state and can be influenced by numerous system operating variables. Multiple regulatory agencies could be involved in the permitting process, so it is advisable to begin permitting discussions early in the planning process to identify applicable permits and specific design and/or operational requirements.

Zoning issues also may enter the picture for a codigestion system, whether at a new or existing facility. For example, an on-farm digester that begins to receive shipments of glycerol or grease-trap pumpout may face the likelihood of a change in zoning classification from agricultural to industrial. As with permitting, it is recommended that zoning discussions be identified early in the planning process to identify potential issues that will need to be addressed.

In summary, the benefits of codigestion are numerous and the current availability and variety of possible substrates will generally improve the economic factors for an AD plant. Competition for the more common codigestates will increase, driving up prices and forcing facilities to consider nonstandard substrates. The search for and use of more unique substrates should be based on a careful assessment protocol to define biodegradability.

As noted, permitting and design issues are evolving as more codigestion systems are proposed and become operable. Employ an AD technology that is flexible in its ability to handle high TS/FOG substrates. If the amount of FOG codigested in an AD system exceeds 10 to 20 percent of the overall feedstock, plan on increased monitoring of system performance and higher maintenance costs. Once the AD plant is operating, collect as much data as possible, as it will be useful in making day-to-day adjustments, fine-tuning the system to achieve maximum efficiency (and return on investment) and troubleshooting problems.

Dennis Totzke, P.E., is a Vice-President at Applied Technologies, Inc. in Brookfield, Wisconsin, an engineering firm specializing in water and wastewater management.

References[edit]

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