Optimization of Biogas Production and Use

Craig, Dustin; Carr, S. N.

doi:10.2175/193864710798255816

Cited by 2 publications

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“…According to a recent report: "Despite 4 individual days being above 0.14 lbs/ ft3/day, there were no weeks that averaged more than 0.11 lbs/ft3/day." (Craig and Carr 2010) The authors conclude that the Des Moines digesters were likely capable of operating at a higher average and peak loading rate due to the ease of digestion the high strength wastes.…”

Section: Case Studies Of Supplementing Digesters For Biogas Productionmentioning

confidence: 99%

Employing Energy Management Planning to Achieve Net Zero Energy in Wastewater Operations

Turgeon¹,

Toffey²

2010

proc water environ fed

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This paper outlines how energy management planning can accomplish dual goals of energy self-sufficiency and optimum treatment processing, and how this provides robust performance and acceptable payback on investment, leading to net zero energy wastewater operations. The energy content of wastewater surpasses the energy required by treatment, reportedly be a factor of up to 10 times. Nevertheless, conventional activated sludge plants with advanced treatment consume typically 1,800 kWh/MG of electricity, but facilities vary from 1,000 to 3,000 kWh/MG. Energy efficiency studies conclude that the potential for energy use reductions through efficient pumps and aerators are on the order of 30 to 50 percent, which is a range of about 400 to 700 kWh/MG. For plants with anaerobic digestion, a rule-of-thumb for electrical production from biogasfueled generators is 500 kWh/MG. Supplementation of anaerobic digesters with high strength organic waste and fats, oils and grease is possible where utilities have excess digester capacity. The experience with supplementation is that facilities have increased biogas by a factor of two or three times pre-existing conditions, and are able to have a corresponding increases in electricity production, where generators have been adequately sized. When thermal heat can be returned for plant processes, overall plant efficiencies rise even higher. Energy planning studies have also shown that innovative technologies that build upon anaerobic processes reduce energy usage from typical values, and, further, energy plans have demonstrated some unexpected results, such as the economic and environmental justification of anaerobic digestion combined with thermal processing, such as dryers and incinerators. While local conditions, particularly energy pricing and government subsidies, likely shape the specific planning objectives and outcomes of any individual plant, the variety of energy efficiency and production technologies that are becoming proven can result in a similar endpoint, and specifically net zero energy wastewater treatment.

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Section: Case Studies Of Supplementing Digesters For Biogas Productionmentioning

confidence: 99%

Employing Energy Management Planning to Achieve Net Zero Energy in Wastewater Operations

Turgeon¹,

Toffey²

2010

proc water environ fed

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“…Revenue can be derived from tipping fees for receiving organic waste, biogas production and residual biosolids. The biogas can be used to fuel a boiler or CHP system, sold to a nearby industry, purified to biomethane and sold as renewable natural gas or compressed and used to fuel compressed natural gas vehicles (Craig 2010). The biosolids can be sold as a soil amendment or as a fuel substitute depending on the local market and solids quality (e.g., Class A or B, dewatered cake or dried pellets, compost, etc.…”

Section: Introductionmentioning

confidence: 99%

Overcoming barriers to codigestion

Parry

Fillmore

2016

Water Practice and Technology

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Codigestion of organic waste with municipal wastewater sludge is growing rapidly. It has many benefits, including diversion of organic waste from landfills, increased renewable energy from biogas production, and potential for revenue from tipping fees. However, there are still barriers to greater widespread application of codigestion. Economics, need for collaboration between utilities, impacts on wastewater application, unsupportive regulations and risks to core wastewater treatment business are obstacles that slow wider adoption of codigestion throughout the world. The research presented analyzes the economic impacts of codigestion, predicts the additional biogas production, and determines the allowable organic loading rate and fats oils and grease (FOG) addition for stable digestion operation. The economic impacts were analyzed on a life cycle cost basis and presented in terms of required tipping fees for different organic wastes, electric rates and residuals handling costs. Standard biochemical methane potential tests were conducted to estimate biogas production from various organic wastes. The specific energy loading rate (SELR) was used to express the allowable organic loading rate. Results from the economic analysis showed that codigestion using existing digesters at a municipal water reclamation facility is more economical than building new digesters. Codigestion was more economical at facilities with high electricity costs and low cost of residuals. Tipping fees for receiving organic waste would be required to offset the net cost of codigestion for wastes other than FOG. There was a net positive economic benefit of receiving FOG without a tipping fee. The upper limit of FOG for stable digestion was found to be 60 percent of the feed by chemical oxygen demand (COD). Stable digestion can be achieved with an SELR of less than 0.25 kgCOD/day/kgVS. The SELR accounts for the strength or energy content of the organic feed measured in COD. It was observed and accounted for by the SELR that anaerobic digesters loaded at higher solids concentrations (resulting in greater inventory of microorganisms in the digesters) can be fed at higher loading rates. Insights into the economics of codigestion and allowable organic loading rates for high strength organic wastes help to overcome some of the barriers to widespread application of codigestion.

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Optimization of Biogas Production and Use

Cited by 2 publications

References 0 publications

Employing Energy Management Planning to Achieve Net Zero Energy in Wastewater Operations

Employing Energy Management Planning to Achieve Net Zero Energy in Wastewater Operations

Overcoming barriers to codigestion

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