Table of Contents
Journal of Waste Management
Volume 2014, Article ID 325341, 9 pages
http://dx.doi.org/10.1155/2014/325341
Research Article

Two-Stage Dry Anaerobic Digestion of Beach Cast Seaweed and Its Codigestion with Cow Manure

Department of Biotechnology, Lund University, P.O. Box 124, 221 00 Lund, Sweden

Received 29 May 2014; Revised 27 June 2014; Accepted 2 July 2014; Published 17 July 2014

Academic Editor: Motoi Machida

Copyright © 2014 Valentine Nkongndem Nkemka et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Two-stage, dry anaerobic codigestion of seaweed and solid cow manure was studied on a laboratory scale. A methane yield of 0.14 L/g VSadded was obtained when digesting solid cow manure in a leach bed process and a methane yield of 0.16 L/g VSadded and 0.11 L/g VSadded was obtained from seaweed and seaweed/solid manure in a two-stage anaerobic process, respectively. The results showed that it was beneficial to operate the second stage methane reactor for the digestion of seaweed, which produced 83% of the methane, while the remainder was produced in the first leach bed reactor. Also, the two-stage system was more stable for the codigestion for seaweed and manure when compared to their separate digestion. In addition, the initial ammonia inhibition observed for manure digestion and the acidification of the leach bed reactor in seaweed digestion were both avoided when the materials were codigested. The seaweed had a higher Cd content of 0.2 mg Cd/kg TS than the manure, 0.04 mg Cd/kg TS, and presents a risk of surpassing limit values set for fertiliser quality of seaweed digestate. Evaluation of the heavy metal content of seaweed or a mixture of seaweed and manure digestate is recommended before farmland application.