Technical Guide 08: The production and use of digestate as biofertiliser

Production and use of Biofertilisers from the Anaerobic Digestion of source separated Organic Wastes

Technical Guidance 8 (TG 8) has been produced to share knowledge and explain the framework that has been developed to eliminate the barriers to using digestate as a fertiliser product. TG8 provides guidance to producers of digestate from an anaerobic digestion facility and to regulators on the criteria on the composition of digestate that can be considered safe to apply to land as a fertiliser. TG8 sets out the differences of  digestate from waste water treatment facilities, and anaerobic digestion  from compost. The framework details how producers of digestate from the anaerobic digestion of source separated organic wastes can become accredited.  Farmers using digestate from accredited producers removes the need for costly and time-consuming resource consents for digestate application to land and creates opportunities for the sale of digestate as biofertiliser products.

TG 8 aims to remove a major barrier to wider investment in AD facilities for recycling of source segregated organic waste by providing a clear specification to plant operators to produce consistently high-quality market-acceptable biofertiliser.  TG8 provides guidance on the application of organic waste material to land:

• biosolids from waste water treatment facilities are regulated by the Biosolids Guidelines (Guidelines for Beneficial Use of Organic Materials on Land ) 
• digestate from anaerobic digestion of organic material is regulated by the Digestate Guidelines (Guidelines for the Production of Digestate Biofertiliser Producer Accreditation Scheme) 
• compost is covered by the composting standard (NZS4454:2005 Composts, soil conditioners and mulches)
• Non complying digestate requires a resource consent.