Agricultural potential of anaerobically digested industrial orange waste with and without aerobic post-treatment

Environ Technol. 2012 Jan-Feb;33(1-3):85-94. doi: 10.1080/09593330.2011.551839.

Abstract

The potential of anaerobically digested orange waste with (AAD) and without (AD) aerobic post-treatment for use in agriculture was evaluated through chemical analyses, short-term phytotoxicity and long-term plant assays. Chemical analyses showed that AD contained ammonia and organic acids, and aerobic post-treatment did not significantly remove these phytotoxins. The N:P2O5:K2O ratio in AD was 1:0.26:0.96 and aerobic post-treatment did not change the composition in AAD except for K2O (1:0.26:1.24). Heavy metal contents in AD and AAD were more or less the same and were below the upper limit recommended for non-sewage sludge application on agricultural soils. Short-term phytotoxicity tests showed that seed germination and root elongation of Chinese cabbage and ryegrass were severely inhibited at digestate concentrations of 60-100%. Germination index values were well below the score of 50% required to indicate the phytotoxic-free nature of compost. Long-term plant assays showed that AD and AAD, when supplemented with a base fertilizer, resulted in higher plant growth, and fresh weight and dry matter production than AD without base fertilizer. The results thus indicate that aerobic post-treatment did not have any significant beneficial effect on reducing phytotoxicity, and AD could be used as such on agricultural soils, especially with high P.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aerobiosis
  • Anaerobiosis
  • Brassica / growth & development
  • Citrus sinensis / chemistry*
  • Citrus sinensis / toxicity
  • Fertilizers / analysis*
  • Fertilizers / toxicity
  • Industrial Waste / analysis*
  • Lolium / growth & development
  • Toxicity Tests

Substances

  • Fertilizers
  • Industrial Waste