Ihsan Hamawand

Waste management in the meat processing industry: conversion of paunch and DAF sludge into solid fuel

This article addresses the novel dewatering process of immersion-frying of paunch and dissolved air flotation (DAF) sludge to produce high energy pellets. Literature have been analysed to address the feasibility of replacing conventional boiler fuel at meat processing facilities with high energy paunch-DAF sludge pellets (capsules). The value proposition of pelleting and frying this mixture into energy pellets is based on a Cost-Benefit Analysis (CBA). The CBA is based on information derived from the literature and consultation with the Australian Meat Processing Industry. The calorific properties of a mixture of paunch cake solids and DAF sludge were predicted from literature and industry consultation to validate the product. This study shows that the concept of pelletizing and frying paunch is economically feasible. The complete frying and dewatering of the paunch and DAF sludge mixture produces pellets with energy content per kilogram equivalent to coal. The estimated cost of this new product is half the price of coal and the payback period is estimated to be between 1.8 and 3.2years. Further research is required for proof of concept, and to identify the technical challenges associated with integrating this technology into existing meat processing plants.

Issues related to waste sewage sludge drying under superheated steam

Abstract Sewage sludge was dried in a rotary drum dryer under superheated steam. Particle size and moisture content were shown to have significant influences on sticking and agglomeration of the materials. Pouring partially dried sludge (70–80% moisture content, wet basis) directly into the screw feeder of the drum dryer resulted in a significant sticking to the surface of the drum and the final particle size of the product was greater than 100 mm in diameter. The moisture content of this product was slightly less than its initial value. To overcome this issue, the sludge was mixed with lignite at variety ratios and then chopped before being introduced to the feeding screw. It was found that mixing the sludge with lignite and then sieving the chopped materials through a four millimetre mesh sieve was the key to solve this issue. This technique significantly reduced both stickiness and agglomeration of the material. Also, this enabled for a significant reduction in moisture content of the final product.

Solar, wind and geothermal energy applications in agriculture: back to the future?

The agri-food chain consumes about one third of the world’s energy production with about 12% for crop production and nearly 80% for processing, distribution, retail, preparation and cooking (Fig. 1.1) (FAO, 2011b). The agri-food chain also accounts for 80–90% of total global freshwater use (Hoff, 2011) where 70% is for irrigation alone. Additionally, on a global scale, freshwater production consumes nearly 15% of the entire energy production (IEA, 2012). It can therefore be argued that making agriculture and the agri-food supply chain independent from fossil fuel use has huge potential to contribute to global food security and climate protection not only for the next decades, but also for the coming century. Provision of secure, accessible and environmentally sustainable supplies of water, energy and food must thus be a priority. One of the major objectives of theworld’s scientists, farmers, decision-makers and industrialists is to overcome the present dependence on fossil fuels in the agri-food sector. This dependency increases the volatility of food prices and affects economic access to sustenance. For example, Figure 1.2 shows the close interrelationship between the crude oil price index and the cereals price index. An increasing energy demand for cultivation is particularly important in regions with expanding irrigated agriculture using pumped water. This translates to a food-related risk to energy security. The development and commercialization of renewable energy sources such as solar, wind and geothermal provides great potential to reduce costs in the agri-food sector. For instance, in addition to power generation, the main uses of geothermal waters are for space heating, district heating, spas balneology, aquaculture and greenhouse heating (Lund and Boyd, 2015). However, much work remains to be done to make better use of renewable energy in the agri-food sector. The aim of this introductory chapter is to critically review recent developments in solar, wind and geothermal energy applications in agriculture and the agri-food sector such as processing, distribution, retail, preparation and cooking.