2.4. Pot experiments
Pot experiments were carried out to investigate the possible use
of the mature sludge obtained from the three above-mentioned
reactors as an organic fertilizer in agriculture and floriculture. For
the control trials, ordinary clayey soil and fresh dewatered sewage
sludge, which were respectively collected from Ma’an MountainForest Park (China) and Jiangxia (China) urban sewage treatment
plant and air-dried, were used. Five Impatiens balsamina seeds were
sown in each pot under constant temperature, light, humidity, and
water frequency. The pots (height = 14 cm, i.d. = 21 cm) were
respectively filled with 3.2 kg of the following materials: (a) ordinary soil, (b) fresh sludge, (c) mature sludge from the ordinary reactor, (d) mature sludge from the solar reactor, and (e) mature sludge
from the greenhouse reactor. Three pots were prepared for each
material. After a 30-day growth period, the leaf number and height
of the plants in each pot, which reflect the growth states, were
measured to evaluate the fertilizer effect of each material.