3. Materials and method
Prototypes of HEVSTOW and APSU were fabricated (Figures 4 and 5) as per
the designs given in Figures 1 and 3, respectively. Close ups of the
typical modules of HEVSTOW, its conveyer belt, and sprinkler system are
shown in Figures 6-8.
To test the functioning of these machines simultaneous but separate
vermicomposting of paper waste and the aquatic weed water hyacinth was
explored with two earthworm species Esienia andrei andLumbricus rubillus . Eight of the 10 modules
(M1-MB) of HEVSTOW were charged with 4
substrate-earthworm combinations, each in duplicate: a) water hyacinth-E.andrei (M1, M2) b) water
hyacinth- L.rubillus (M3, M4), c)
paper waste- E.andrei , (M5, M6)
and d) paper waste L.rubillus (M7,
M8). The remaining two modules were used to maintain
cultures of E.andrei and L.rubillus respectively. All the
modules had 3 mm thick water-soaked bedding of jute cloth at their
bottom and the feed was laid uniformly over it.
Whole plants of water hyacinth, collected from ponds situated near the
author’s work-place, and chopped to pieces of 8±2 cm length were fed
directly to M1-M4. Paper waste was
pre-soaked in water containing 10% (w/v) fresh cow-dung with APSU, and
fed to M5-M8. In all cases fresh weights
of the substrates equivalent to the corresponding 200 g of dry weight
were taken. For this purpose dry weights were determined by oven-drying
pooled samples of fresh substrates to their constant weights at 105ºC.
In the like manner dry weights were determined of the vermicast
generated and the extents of vermicompost granted per earthworm have
been computed on the basis of dry weights.
In each module 50 adult and healthy individuals of the corresponding
species of earthworms, randomly picked from their culture, were
released. The sprinkler system was set to maintain a moisture level of
60±10% in each module.
After 20 days of start of the experiment the modules were emptied one by
one and the vermicast, the earthworm, and the unconsumed substrate were
separated using the substrate-earthworm-vermicompost-separation (SEVS)
machine designed earlier by us (Tauseef et al., 2014; Abbasiet al., 2019). Simultaneously all the modules were charged with
fresh substrate of the same quantity as was used at the start and the 50
adult earthworm, separated from the contents of that module in the
previous batch by the SEVS machine, were reintroduced into that module.
The juveniles and cocoons found in the unused substrate, nor the unused
substrate, were reintroduced. All subsequent 20-day runs were carried
out in the same fashion. This manner of vermireactor operation has been
named pseudo-discretized continuous operation protocol (PDCOP) by us, as
detailed elsewhere (Nayeem-Shah et al., 2015). It has the
advantage of enabling us to measure the rate of vermicast generated per
adult earthworm as a function of duration of the experiment while not
allowing factors such as a) natural biodegradation of the unused
substrate in the vermireactor with time, and b) feeding by offspring
born in the reactors, to exert any significant influence on that
assessment. Thus, eventhough each reactor was operated in discreet
20-day pulses, its measure of vemricast production was as if the reactor
was operated continuously, with the worms predominantly feeding on the
fresh (or nearly fresh) substrate all through.