Recovery of Waste Farm After Methanation by Evaporation on Inclined Plate

 

Recovery of Waste Farm After Methanation by Evaporation on Inclined Plate

Hiba Zouaghi (1), Souad Harmand (2), and Sadok Ben Jabrallah (3)

(1) H. Zouaghi 

National Engineering School of Monastir, Avenue Ibn El Jazzar, Monastir 5019, Tunisia

e-mail: hibazouaghi@yahoo.fr

(2) S. Harmand

University of Lille Nord, UVHC, LAMIH UMR CNRS 8201, Mont Houy, Valenciennes,

Cedex 09 59300, France

(3) S.B. Jabrallah

Sciences Faculty of Bizerte, Zarzouna, Bizerte 7021, Tunisia

© Springer International Publishing AG, part of Springer Nature 2018

F. Aloui, I. Dincer (eds.), Exergy for A Better Environment and Improved

Sustainability 1, Green Energy and Technology,

https://doi.org/10.1007/978-3-319-62572-0_42 

Wastes present problem for the entire population because of the nuisance it causes. In rural communities, it is rather animal waste, which causes a big problem (soil pollution, rivers, water table, etc.). These releases have a product rich in nutrients and fertilizers (Granier and Texier 1993). On this basis, several farmers choose recovery of such wastes by anaerobic digestion. The development of biogas plants not only reduces agricultural emissions by converting biomass but also thermal energy. This thermal energy can have other uses.

After anaerobic digestion, it leads to the production of two types of energy. One is related to the production of electricity and the other is reused in methanation process. The problem is that digestate, which causes, after anaerobic digestion, a problem on many levels. It has a high water content (up to 97%), particularly pig manure. That’s why a storage or reuse is required. This product is the material remaining residue at the end of the process. It has excellent agronomic value and can be used as fertilizer (Latimier et al. 1996; Levasseur 1998).

The field of waste recovery appeared since a long time, especially in regard to farm waste, because of organic matter and fertilizers. Drying presents an important process for the management of farm waste, as it reduces mass and volume of the product and therefore cost of storage, workforce, and transportation. It’s a method based on evaporation. This process, which is a change of vapor liquid phase, can be achieved by exposure to air. But, it can be intensified by the use of solar energy.

This is one of the most practical of preserving the quality of agricultural products and recycling of waste and effluents methods. Studies on drying after anaerobic digestate are rare. However, other waste streams drying exist.

Drying is an important process for the management of sewage sludge, as it can reduce weight and volume of the product and therefore cost of storage, handling, and transportation. Solar drying plant of sewage sludge treatment was built as a tunnel-type greenhouse with a ceiling height of 2.5 m in Turkey (Salihoglu et al. 2006). It has been completely covered by two walls, with a thickness of 10 mm of transparent polycarbonate with light-transmitting sheet of 80%. Solar dryer was constructed with the principle of increasing the difference between vapor pressure of sludge compared to interior and relative vapor pressure to obtain an effective drying. Lei et al. (2009) developed a greenhouse solar dryer in China for drying sludge from wastewater treatment. The greenhouse is made of glass. Its inner lower surface is painted black in order to increase the absorption of solar radiation. A high stack of 180 cm was placed on top of the greenhouse. Samples of fresh sludge were obtained from wastewater treatment plant located in Shanghai.

Initial slurry humidity is 5.16 kg/kg dry and dried at 0.78 kg/kg dry. It was rolled to 25 mm in thickness in a plate which was made from 0.1 mm steel mesh and a surface area of 0.22 m
0.36 m. The drying process lasts 125 h in summer and about 550 h in winter with a non-regular decrease in moisture content (Bennamoun 2011).

Tannery effluent, ejected at environment, pollutes terrestrial and aquatic organisms in and around tanneries and evaporates over long periods. Drying may be accomplished by allowing effluent to flow on an inclined plane solar sensor. While liquid flows over collector, it is heated by solar energy that will help the increase of evaporation rate. In tannery, water effluent evaporation and recovery of salt is one of methods using solar energy available in abundance (Mani and Srinivasa Murthy 1993, 1994; Srithar and Mani 2003, 2004, 2006) used driers having sensor solar plates and a spray system to increase evaporation flow. In the case of plate sensor, effluent flows over the manifold. Therefore, effluent temperature at exposure area with air increases, which increases the rate of evaporation.

This work relates to drying of pig undergoing anaerobic digestate and a separation phase by centrifugation. Treated effluent has a solids content of 2.3%. In this context, an inclined stainless steel plate 2 m long, 1 m wide, and inclined by 30° has been put in place. The device is without a glass cover, and tests are carried in laboratory using a solar simulator in which power is 6000 W. This device is designed to be placed on barns roofs.

This study is divided into two parts. In the first part, evaporation tests were conducted by varying the inlet temperature of effluent. The second part will focus on comparison between experimental and calculated results by solving equations of heat and mass balances on plate and film.