Modeling and cost estimation of energy production from sludge

Abstract

Energy recovery from sewage sludge offers an opportunity for sustainable management of sewage sludge and energy. Anaerobic digestion and pyrolysis are among the most promising processes applicable for sewage sludge-to-energy conversion. Anaerobic digestion of sewage sludge forms methane-rich biogas, which can be utilized as fuel to offset heat and electricity consumption of the wastewater treatment sector. However, the digestion process has the efficiency limitation since it cannot sufficiently extract the energy from sewage sludge. The digested sludge is still energy profitable and it contains considerable organic matter, but poor in biodegradability. This paper presents a brief overview of anaerobic digestion, pyrolysis, and the combination of other processes with anaerobic digestion in the application to bio energy production from sewage sludge. An assessment of energy conversion of five sludge to energy pathways is also presented. The pathways via pyrolysis and the combination of anaerobic digestion, thermal hydrolysis, and thermal drying could achieve higher energy efficiency compared to other pathways.

Utilizing a CHP Power Plant’s Energy and CO2 Emissions for the Manufacture of Affordable and Carbon Neutral Algae Bioplastic for Re-Useable Packaging

“…In EH the algae cell wall carbohydrates are biochemically broken down into sugar monomers . In effect, this makes the algae’s lipids and amino acids accessible in the hydrolysate. , Since most microalgae biomass production is constrained to high quality-nutrients and chemical products harsh techniques such as acid and alkaline thermal pre-treatment ,, must be avoided to acquire algae lipid oils, carbohydrates, and amino acids safely to get the most effective value out of the biomass’s cell content. ,, Although EH can be technically cumbersome and can require higher material cost expenditure compared to other processes at large scales, , it was chosen as it is an efficient and sustainable means of using enzymes to convert the cell’s wall into intermediates to derive valuable products while avoiding the toxicity, inhibitors, and waste streams of chemical hydrolysis and the high costs and energy intensity of thermal hydrolysis − or mechanical pre-treatment such as high-pressure homogenization (HPH) or bead or ball milling. ,− After EH, the algae biomass slurry is dried at low temperature in a mechanical vapor re-compressor to roughly 40.0% solids to ease accessibility to algae hydrolysate’s contents . The processing conditions and resources for EH are derived from the experimental procedures of the Technical University of Munich’s (TUM) Werner Siemens Chair of Synthetic Biotechnology (WSSB) for various algae species…”