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.