3. Results and discussion
3.1. Obtaining filtrate with controlled quality parameters
To obtain a high-quality filtrate, the pig manure treatment
process should be properly controlled. We examined whether the
total solid (TS) content in raw pig manure and the quantity of superphosphate and lime milk added during treatment might influence the concentrations of COD, N, and P in the produced filtrate.
3.1.1. Influence of total solids of raw pig manure in the filtrate
composition
Our “raw pig manure A” sample contained 11.5% TS and
8.65 g L1 TKN, 117.25 g L1 COD, and 2.42 g L1 P. Samples were
diluted with water to different TS contents (Table 1) and treated
according to the method described in Section 2.2. Superphosphate
was added in amounts that equaled 4% of the raw manure weight.
The results (Table 1) showed that dilution of the TS could increase the filtration rate of treated manure. The highest filtration
rate (3700 kg m 2 h 1) was observed when the TS content was
2e3%. The filtrate obtained from manure with 2% TS had the lowest
pH (4.7). Filtrate samples from manure with 7e10% TS had pH
values > 8