Effects of municipal sludge and treated waste water on biomass yield and fiber properties of kenaf (Hibiscus cannabinus L.)

Published Date
Industrial Crops and Products
June 2016, Vol.84:7–12, doi:10.1016/j.indcrop.2016.01.040

• Author 

• C. Ververis ^a,,,
 
• N.S. Christodoulakis ^a
 
• R. Santas ^b
 
• Ph. Santas ^b
 
• K. Georghiou ^a

• aNational and Kapodistrian University of Athens, Faculty of Biology, Department of Botany, Panepistimiopolis, Athens GR 157 84, Greece
• bOikotechnics Institute, Kefallenias 50, Ano Helioupolis GR 163 42, Greece

Received 2 June 2015. Revised 21 January 2016. Accepted 24 January 2016. Available online 8 February 2016. 

Highlights

• •
  We experimentally cultivated kenaf using municipal sludge and treated waste.
• •
  We also cultivated kenaf using conventional fertilizers and water.
• •
  No differences in biomass between conventional and experimental plots.
• •
  No differences in fiber properties between the two cultivation methods.
• •
  Premature harvest leads to significant biomass loss.

Abstract

Kenaf (Hibiscus cannabinus L.) was experimentally cultivated with the use of digested, dried sewage sludge (130 t/ha) and water from a municipal Sewage Treatment Plant (STP) in order to assess their potential to replace conventional fertilization (100 kg N/ha, 75 kg P₂O₅/ha and 75 kg Κ₂O/ha) and irrigation. Tap water and treated wastewater were used for irrigation in quantities corresponding to 6500 m³/ha. Four different treatment combinations were applied as follows: (a) wastewater irrigation and conventional fertilization, (b) wastewater irrigation and sewage sludge fertilization, (c) tap water irrigation and sewage sludge fertilization, and (d) tap water irrigation and conventional fertilization. The dry plant biomass collected in the final harvest (140 days after plant emergence) from the four treatment plots was 12.3 t/ha, 12.6 t/ha, 12.4 t/ha and 12.8 t/ha respectively. These differences were not statistically significant (ANOVA, P = 0.05) and, therefore, it was concluded that the use of municipal wastes had similar effects on dry biomass production with that of conventional fertilization. An earlier harvest (125 days after plant emergence) gave 11.3% lower dry biomass on average in relation to the second harvest, and this difference was statistically significant (ANOVA, P = 0.05). Premature harvest may lead to significant biomass losses, so the plant must be collected during its technological maturity stage. There was not any statistically significant difference among the four treatments and between the two harvests in fiber dimensions and derived values (suitability indices for paper manufacture). On the other hand, cellulose and lignin content in the second harvest were significantly higher compared to the first one, whereas no significant differences were detected among the four treatments.

Keywords

Kenaf

Sewage sludge

Municipal waste

Biomass 

Fiber properties

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Table 4.

• ⁎ 
  Corresponding author. Present address: Ministry of Environment and Energy, Directorate of Environmental Planning, Biodiversity and Protected Areas Section. 147, Patision St., Athens GR 112 51, Greece. Fax: +30 210 8662024.

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