Performance, Energy Consumption and Energetic Efficiency Analysis of 25 Solar Sludge Dryers

Bux, M.; Baumann, Reto

doi:10.2175/193864703784755418

Cited by 7 publications

(12 citation statements)

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“…These conditions are adequate for solar drying. Typically solar drying processes are capable of providing evaporation rates between 1 and 3.3 kg water /m 2 .day (Bux and Baumann, 2003). The design for Malabar is based on 2.2 kg water/m 2 .day.…”

Section: Process Sizingmentioning

confidence: 99%

Introduction of Solar Drying Technology to Trinidad and Tobago

Mangat¹,

McTaggart²,

Marx³

et al. 2009

proc water environ fed

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A review of the existing solids management practices in Trinidad and Tobago and experience elsewhere defined the future needs and identified solar drying as a preferred technology for the subject project. Upon analysis of the local conditions, it was calculated that approximately 19 MJ/m 2 (1886 kWh/m²) of solar radiation, at 30ºC annual average temperature and 80% relative humidity level is appropriate at the project site and that these parameters are adequate for the solar dryer application. The estimated 7,450 m 2 cell area for drying associated with average electrical power consumption of 18 to 20 kWh/tonne of water extracted will provide an evaporation rate of 2.2 kg water/m 2 .day. The solids are expected to be dried from approximately 16-18% dry solids to 70-90% dry solids.

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Section: Process Sizingmentioning

confidence: 99%

Introduction of Solar Drying Technology to Trinidad and Tobago

Mangat¹,

McTaggart²,

Marx³

et al. 2009

proc water environ fed

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show abstract

“…In addition to enhancing the available heat generated by solar energy, the greenhouse helps to contain odors that might be generated by the drying biosolids. To enhance drying, the newer generation of solar dryers employs automated mixing and control of the climate within the greenhouse [1]. There are three commercial examples, distinguished by mixing systems and number of commercial scale installations.…”

Section: Introductionmentioning

confidence: 99%

“…The system using the electric mole is able to process solids with solids concentrations as low as 3%, while the other two methods require a total solids concentration (TS) of 20% or greater [2]. Overall, these systems have been used in smaller plants, ranging from those serving 1000 population equivalents (PE) to those serving 300,000 PE [1].…”

Section: Introductionmentioning

confidence: 99%

Enhanced Biosolids Drying with a Solar Thermal Application

Jolis¹

2017

J Fundam Renewable Energy Appl

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Covered, green-house type biosolids solar drying facilities provide a low-energy option with operational simplicity and reduced cost. However, their large footprint consequence of low water evaporation rates make them unattractive for large wastewater treatment plants in urban areas with limited available space. This project investigated whether recent advances made in solar thermal technology conferred sufficient benefit in water evaporation rates that solar drying of wastewater biosolids may be feasible. A demonstration solar drying chamber was constructed with warm air from a solar thermal panel being routed to the chamber to aid in evaporation. Experiments were conducted with water alone to measure water evaporation rates in a range of weather conditions and to develop a regression model for evaporation. Experiments were also conducted with digested, dewatered biosolids to measure evaporation rates when drying biosolids. Total solids concentration in biosolids samples reached 42.3% after 102 hours in the dryer. Data showed that evaporation rates strongly depend on the temperature inside the dryer chamber but also on biosolids mixing. Measured evaporation rates were more than twice those previously reported in the literature for solar dryers and imply that with an experimental setup optimized for mixing, humidity control and energy recovery, still higher rates could be achieved. If confirmed in larger scale demonstration projects, the results from this study would allow for compact solar dryers to be located in urban settings.

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“…Sewage sludge should contain high DS in order to enhance combustion efficiency, provide safe operation and reduce emissions during combustion (Chai, 2007). Meanwhile, high DS is essential to meet the criteria in regulations relevant to sewage sludge landfilling and reduces transportation costs of sludge to agricultural lands (Chai, 2007;Bux and Baumann, 2003). In Turkey, the Landfill Directive of EU is adopted and this regulation (MoEF, 2010a) restricts sludge disposal into landfills unless DS is greater than 50%.…”

Section: Introductionmentioning

confidence: 99%

“…A GSD is cheaper, its operation is easy, and it does not need skilled labor compared to thermal dryers (Ritterbusch and Bux, 2012). It is environmentally friendly and has very low CO 2 emissions compared to thermal dryers as no fossil fuel is used or little energy is used for ventilation and mixing only (Bux and Baumann, 2003). Nevertheless, this system cannot reach 90% DS at reasonable time periods compared to thermal dryers although good results have been reported in warm climates (Seginer et al, 2007;Bennamoun, 2012;Meyer-Scharenberg and P€ oppke, 2010).…”

Section: Introductionmentioning

confidence: 99%

Evaluation of solar sludge drying alternatives by costs and area requirements

2015

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Thermal drying is a common method to reach above 90% dry solids content (DS) in sludge. However, thermal drying requires high amount of energy and can be expensive. A greenhouse solar dryer (GSD) can be a cost-effective substitute if the drying performance, which is typically 70% DS, can be increased by additional heat. In this study feasibility of GSD supported with solar panels is evaluated as an alternative to thermal dryers to reach 90% DS. Evaluations are based on capital and O&M costs as well as area requirements for 37 wastewater treatment plants (WWTPs) with various sludge production rates. Costs for the supported GSD system are compared to that of conventional and co-generation thermal dryers. To calculate the optimal costs associated with the drying system, an optimization model was developed in which area limitation was a constraint. Results showed that total cost was minimum when the DS in the GSD (DS(m,i)) was equal to the maximum attainable value (70% DS). On average, 58% of the total cost and 38% of total required area were associated with the GSD. Variations in costs for 37 WWTPs were due to differences in initial DS (DS(i,i)) and sludge production rates, indicating the importance of dewatering to lower drying costs. For large plants, GSD supported with solar panels provided savings in total costs especially in long term when compared to conventional and co-generation thermal dryers.

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Performance, Energy Consumption and Energetic Efficiency Analysis of 25 Solar Sludge Dryers

Cited by 7 publications

References 0 publications

Introduction of Solar Drying Technology to Trinidad and Tobago

Introduction of Solar Drying Technology to Trinidad and Tobago

Enhanced Biosolids Drying with a Solar Thermal Application

Evaluation of solar sludge drying alternatives by costs and area requirements

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