Journal of Ecology and Rural Environment ›› 2016, Vol. 32 ›› Issue (1): 126-132.doi: 10.11934/j.issn.1673-4831.2016.01.021

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Properties of Earthworm Digested Sewage Sludge and Effects of the Sludge on Growth of Coleus blumei

HUO Qing-lin, XU Xiao-xun, ZHANG Shi-rong, DENG Qian-xi, ZHANG Chi-qiang, DENG Yu-lan, DONG Yuan-yuan   

  1. College of Environmental Sciences, Sichuan Agricultural University, Chendu 611130, China
  • Received:2015-08-14 Online:2016-01-25 Published:2016-01-27

Abstract:

A pot experiment was carried out using earthworm(Pheretima) digested sewage sludge as ingredient mixed with soil at different ratios to form culture medium for growth of Coleus blumei to explore changes in properties of the sewage sludge after digestion by earthworms and effect of the use of the earthworm digested sewage sludge at different rates on growth of C. blumei. Results show that pH, water content, total nitrogen, total phosphorus, alkalyzable N, readily available phosphorus, readily available potassium and organic matter were lower in the digested sludge than in untreated sludge, and wet bulk density of the digested sludge was 38.89% lower, while porosity was 93.91% higher, which indicates that earthworm digestion improves properties of the sludge as culture medium. Eearthworms may bio-accumulate heavy metals from sewage sludge. Digestion lowered the content of Pb, As, Hg and Zn, but raised that of Cu and Cd in the sludge, making it up to the criteria for neutral and alkaline soils of GB 4284-84"Standards for Control of Pollutants in Sludge for Agricultural Use". In the culture medium soil enzyme activity increased with rising rate of digested sludge used, and moreover, the plants growing in the medium mixed with digested sludge are much better than those growing in untreated sludge and in CK(100% soil) in growth morphology and physiological property, which indicates that 100% earthworm digested sludge can be used as very good medium for cultivation of C. blumei.

Key words: earthworm, domestic sewage sludge, Coleus blumei, growth

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