Introduction

Whole Systems Approach to Ecological Design

Appropriate Technology: Water

Organic Agriculture and Local Food

Appropriate Technology: Energy

Green Building & Retrofitting

Anaerobic Digestion

Anaerobic digestion of wastewater produces less biomass than aerobic processes (Peavy et al. 1985).  There are two types of organisms that are essential for the breakdown of wastewater solids.  Acid formers are facultative anaerobic bacteria that breakdown organic solids through hydrolysis.  Fermentation into acids and alcohols follows.  Methane formers are strict anaerobic bacteria that convert the acids and alcohols to methane (Peavy et al. 1985).   Methane formers are delicate and require a narrow pH of 6.5 to 7.5 and may be sensitive to sudden changes in other environmental factors such as temperature, food supply, etc.  For this reason, methane formers are not always present in septic tanks.

• Anaerobic Digestion
• Aerobic digestion
• Nitrification
• Denitrification
• Plant Rhizospheres