Samples were taken from raw slurry collecting basin before the inlet in to bioreactor input samples, from outlet of digested slurry after methanogenesis in bioreactor output samples, fro
Trang 2Picture 1 Polyurethane carrier with adhered A suum eggs
Picture 2 Perforated plastic nets with the carriers
The samples were examined for the pH (1:10 water extract) using a pH electrode (HACH Company, Loveland, Colorado, USA) Dry matter (drying at 105°C to a constant weight), residum-on-ignition (550°C for 4 h), and water soluble ammonium nitrogen (NH4+) by titration (Mulvaney, 1996) Soluble and insoluble substances were determined by evaporation of the known amount of homogeneous sample filtrate on a water bath after
Trang 3absorption of insoluble substances on a filter, drying the evaporation residue at 105°C and determining its weight COD was determined on the basis of organic substances oxidation
in sample by potassium dichromate in sulfuric acid medium during 2-hour boiling in a COD reactor (HACH Company, Loveland, Colorado, USA) Portion of samples for Nt
determinations were digested using a HACH-Digesdahl apparatus (HACH Company, Loveland, Colorado, USA) Nt was distilled with NaOH (40 %) (Bremner, 1996) The C content was calculated according to the content of OM by the method of Navarro et al (1993) to obtain the C:N ratio
2.3 Statistical analysis
The physical and chemical properties (pH, DM, IM, OM, NH4+, Nt,) of solid animal wastes,
as well as the number of demaged eggs were expressed as mean values ± standard deviation (x±SD)
Significance of differences between experimental and control groups of parasites were determined using Student t-test, ANOVA and Dunnet Multiple Comparison test at the levels of significance 0.05; 0.01 and 0.001 (Statistica 6.0)
Results
a) Anaerobic stabilisation of liquid animal wastes
Investigations were carried out under operating conditions of the large-capacity pig farm in Slovak Republic (Picture 3) Technological equipment for anaerobic treatment of pig slurry
on the principle of methanogenesis with the production of biogas was built up on the farm (Picture 4) Pig slurry was treated in the bioreactor (2 500 m3) manufactured by Mostáreň Brezno under the agreement with the firm BAUER Voitsberg The stirring of the substrate in this reactor was done at the expense of energy of the generated biogas Mean daily input of raw pig slurry in bioreactor of biogas plant varied between 78 and 144 m3 The volume of digested slurry after methanogenesis was equal to that of the input Two lagoons were the part of the biogas plant The volume of larger lagoon is 20 000 m3 (Picture 5) and that of smaller lagoon is 5 000 m3 Both lagoons serve as reservoirs of digested slurry Liquid fraction from the smaller lagoon was carried away and spread on fields The presence and survival of parasite eggs were studied in the larger lagoon Samples were taken from raw slurry collecting basin before the inlet in to bioreactor (input samples), from outlet of digested slurry after methanogenesis in bioreactor (output samples), from supernatant (liquid fraction) and from lagoon sludge (solid fraction - sediment) The slurry samples for parasitological and physical and chemical examination were collected monthly during 29 month
Slurry from the pig farm stored in the collecting basin showed a considerable variability during the period of study (Table 1) Compared with mean pH value of 7.12 ± 0.26, pH raw slurry in the month 11, 17 and 21 was lower, ranging between 6.61 and 6.95 The most conspicuous differences were recorded in DM content, which is most likely associated with the amount of process water use The DM content in raw slurry determined during the period studied ranged from 0.81 % to 5.30 % The amount of NH4+ in raw slurry was between 821 mg.l-1 and 1 774 mg.l-1 Chemical oxygen demand (COD) for that period varied from 2 000 mg.l-1 to 22 530 mg.l-1 The mean contents of Nt, in slurry was 1 445 ± 420 mg.l-1
Trang 4Picture 3 Large-capacity pig farm
Picture 4 Bioreactors of biogas plant
Trang 5Picture 5 Large lagoon for storing digested pig slurry
Picture 6 Embryonated A suum eggs
Like raw pig slurry also slurry stabilised by anaerobic process showed variability of its physical-chemical parameters on its out flow from bioreactor (Table 2) Conspicuous differences were observed mainly in the dry mater content of anaerobically stabilized slurry
Trang 6This is caused by the projected input, reckoning on the 5 % of dry matter in raw pig slurry, but the mean dry matter content in raw slurry supplied to bioreactor was 1.96 % and therefor poultry excrements had to be regularly added (average DM content 22.27 %) to pig slurry prior to its supply into bioreactor Stabilized slurry outlet of bioreactor contained as much as 3.23 ± 2.54 % DM on the average Anaerobic digestion increased slurry pH which was ranging from 7.37 to 8.50 Compared with untreated slurry, anaerobic stabilization increased the content NH4+ to 7.80 ± 0.29 mg.l-1 on average Concentration of Nt was increased twice
Storage
(month) pH (mg.l COD -1 ) DM (%) (%) IM OM (%)
Soluble substances (mg.l -1 )
Insoluble substances (mg.l -1 )
(mg.l -1 ) (mg.l N t -1 )
0 7.44 14 833 2.75 31.87 68.13 11 263 16 264 1 774 2 419
1 7.34 2 000 0.84 51.42 48.58 5 836 2 612 1 186 1 401
2 7.17 9 297 0.95 43.04 56.96 4 561 4 897 821 1 195
3 7.03 13 500 1.14 57.71 42.29 7 757 3 641 1 202 1 485
4 7.00 20 900 1.57 38.74 61.26 11 095 4 572 1 078 1 363
5 7.35 14 824 0.81 45.71 54.29 4 895 3 178 1 037 1 191
6 7.36 13 333 2.52 17.36 52.64 5 366 19 844 1 247 1 429
11 6.61 21 795 5.30 33.02 66.98 - - 1 695 1 089
17 6.95 12 750 0.95 30.53 69.47 1 000 8 500 1 478 1 010
21 6.95 22 530 2.80 19.97 80.03 5 870 22 130 1 358 1 872
Table 1 Physico-chemical properties of raw pig slurry (input sample of bioreactor) (COD – chemical oxygen demand, DM - dry matter, IM - inorganic mater, OM - organic matter;
NH4+ - ammonium ions, Nt - total nitrogen, - - not examined)
Storage
(month) pH (mg.l COD -1 ) DM (%) (%) IM OM (%)
Soluble substances (mg.l -1 )
Insoluble substances (mg.l -1 )
(mg.l -1 ) (mg.l N t -1 )
1 7.74 10 500 0.81 56.54 43.46 4 739 3 401 2 204 2 605
2 7.63 17 820 1.24 48.50 51.50 6 134 6 226 2 157 2 699
3 7.80 8 500 1.96 59.69 40.31 6 192 13 456 2 045 2 549
4 7.69 17 100 3.16 41.81 58.19 5 965 5 658 1 933 3 138
5 7.77 6 092 4.48 42.06 57.94 3 225 41 603 1 898 1 982
6 7.92 2 186 2.91 42.87 57.13 3 555 25 518 2 437 3 516
11 7.88 4 872 0.50 70.00 30.00 - - 2 171 1 530
17 7.37 7 750 6.45 39.84 60.16 1389 63 111 2 248 1 936
21 7.66 42 169 7.85 33.81 66.19 1 333 77 167 2 655 3 399
Table 2 Physico-chemical properties of digested pig slurry (output sample of bioreactor) (COD – chemical oxygen demand, DM - dry matter, IM - inorganic mater, OM - organic matter; NH4+ - ammonium ions, Nt - total nitrogen, - - not examined)
Trang 7Anaerobically stabilized slurry was pumped from bioreactors into slurry ground lagoon for further storage A long-term storage of digested slurry in lagoon is the most effective way of treatment resulting in a elimination of helminth eggs (Schwartzbrod et al., 1989) At the same time there is an increase in biogenic elements, especially of nitrogen and phophorus which are transformed into the forms acceptable by plants Results of the chemical analysis
of liquid fraction (supernatant) are presented in Table 3 and those of solid fraction (sludge)
of lagoon in Table 4 pH of supernatant has not changed much over the period studied Mean pH was 8.20 ± 0.11 % Sediment pH decreased during the first period of the study (month 0-6) and than again increased Ammonia content was about equal in both the fraction The highest content of NH4+ was detected in spring month with its decrease observed in the course of study Nt contained by supernatant samples varied between 882 mg.l-1 to 2 283 mg.l-1 (Table 3) and in sediment between 3 571 mg.l-1 to 57 831 mg.l-1 (Table 4) Sediment contained more DM and Nt than supernatant (Tables 3, 4)
Storage
(month) pH (mg.l COD -1 ) DM (%) (%) IM OM (%)
Soluble substances (mg.l -1 )
Insoluble substances (mg.l -1 )
(mg.l -1 ) (mg.l N t -1 )
0 8.30 4 500 0.50 61.06 38.94 4 416 581 1 737 1 910
1 8.20 4 000 0.50 70.39 29.61 4 808 174 1 307 1 428
2 8.17 2 002 0.68 57.58 42.42 6 579 239 1 345 1 569
3 8.34 3 500 0.66 57.75 42.25 5 340 1 272 1 111 1 214
4 8.10 7 600 0.93 56.04 43.96 6 085 3 177 1 408 1 662
5 8.08 6 552 0.87 52.76 47.24 3 600 5 255 1 135 1 172
6 8.29 1 530 0.71 57.59 42.41 2 748 4 337 1 107 1 223
13 8.21 7 059 0.70 55.53 44.47 5 954 1 083 1 863 2 283
14 8.07 818 1.68 46.60 53.40 5 588 11 217 1 569 1 569
15 8.28 1 904 0.66 54.83 45.17 5 325 1 284 1 331 1 317
16 8.21 5 385 0.63 56.38 43.62 4 483 1 806 896 882
17 8.29 8 605 0.60 54.27 45.73 3 501 2 524 616 1 415
23 8.32 3 333 0.35 71.43 28.57 2 128 1 372 672 1 016
29 7.95 5 000 0.75 45.33 54.67 3 000 4 500 862 1 031 Table 3 Physico-chemical properties of supernatant from stabilized pig slurry stored in lagoon (COD – chemical oxygen demand, DM - dry matter, IM - inorganic mater, OM - organic matter; NH4+ - ammonium ions, Nt - total nitrogen, - - not examined)
A sum eggs and Oesophagostomum sp eggs were rarely detected in slurry on the input and
also on the output of bioreactor (Table 5) Similar results of helminths eggs occurrence in anaerobic slurry treatment were also presented by Juriš et al (1996), No helminth eggs were
found in the supernatant of digested slurry from the lagoon A suum eggs were found in
sediment (Table 5)
High percentage of devitalised unembryonated A suum eggs (47.46 ± 0.78 %) stored 11
months (from May – month 13 to March - month 23) in a ground slurry lagoon points to the impact of high concentration of NH4+ (max 5 358 mg.l-1 in sediment compared to 1 863 mg.l
-1 in supernatant), which are releasing during a period of time from an open area of the
Trang 8ground lagoon, and nitrogen (max 9 854 mg.l-1 in sediment compared to 2 283 mg.l-1 in supernatant) on devitalization of developmental stages of endoparasites The number of
devitalised A suum eggs increased towards to the bottom of lagoon In the control groups, only 19.60 ± 1.80 % of A suum eggs were devitalized (Table 6)
Storage
(month) pH (mg.l COD -1 ) DM (%) (%) IM OM (%)
Soluble substances (mg.l -1 )
Insoluble substances (mg.l -1 )
(mg.l -1 ) (mg.l N t -1 )
0 8.37 9333 1.17 49.21 50.79 1 885 2 138 5 778 5 963
1 8.13 11000 1.17 48.26 51.74 1 681 1 830 5 635 6 041
2 8.07 6170 1,70 43.21 56.79 1 643 2 241 7 344 9 652
3 8.09 4500 1.28 31.52 52.88 1 363 1 625 4 042 6 782
4 7.90 55100 1.12 34.90 65.10 1 359 2 437 3 913 7 298
Table 4 Physico-chemical properties of sediment from stabilized pig sllury stored in lagoon (COD – chemical oxygen demand, DM - dry matter, IM - inorganic mater, OM - organic
matter; NH4+ - ammonium ions, Nt - total nitrogen, - - not examined)
Table 5 Occurence of helminth eggs in slurry and in lagoon (A – A suum eggs, Oe –
Oesophagostomum sp eggs, ND – not detected, - - not examined)
0 1 2 3 4 5 6 11 13 14 15 16 17 21 23 29
Input
Output
Supernatant
Sediment
Trang 9Storage (month) Damaged A suum eggs (x%±SD)
Lagoon Control
Table 6 Damage of A suum eggs during long term storage of anaerobic stabilized pig slurry
in lagoon
b) Anaerobic stabilisation of solid animal wastes
The effect of anaerobic stabilisation of solid animal wastes (manure, dog excrements) with
or without addition of lime on the survival of parasitic germs were studied under laboratory
conditions Two types of lime was used in the experiment: 1 quality dust lime and 2 dust
rejects from lime production caught on the electrostatic precipitator General characteristics
of tested lime are given in Table 7
Table 7 Physico-chemical properties of the tested types of lime
Pig manure (M) and dog excrements mixed with hay in the ratio of 1:5 (D) were used in the
experiment Organic wastes were mixed with tested lime in a different concentration and
periodically stirred The following variations were investigated in comparison to untreated
(control) manure (CM) and untreated dog droppings (CD):
a manure mixed with quality dust lime in a concentration of 20 g.kg-1 (ML20)
b manure mixed with dust rejects in a concentration of 20 g.kg-1 (M20)
c dog droppings mixed with dust rejects in a concentration of 20 g.kg-1 (D20),
d dog droppings mixed with dust rejects in a concentration of 70 g.kg-1 (D70)
Samples for parasitological and physical and chemical examinations were collected after 0,
1, 3, 8, 14, 36 (UM, ML20 and M20) and after 0, 1, 2, 3, 7, 8, 9, 10, 14, 73 (UD, D20, D70) days
of exposure Three samples were taken and analysed at each of the given sampling intervals
The physical and chemical properties of treated manure and dog excrements are given in
Tables 8 - 13 Comparison of the changes in The physical and chemical propertiesof organic
material during anaerobic stabilisation with or withou dust rejects is given in Fig 1 – 5
Trang 10Storage
0 8.47±0.58 33.22±6.88 8.09±2.57 91.91±2.57 120.89±7.05 13789.52±2356.62 34.27:1
1 8.57±0.02 20.66±4,29 10.41±0.72 89.58±0.72 257.65±10.10 51930.16±421.47 8.84:1
3 9.52±0.06 28.06±5.41 6.03±0.11 93.37±0.11 176.37±8.09 46522.24±2310.56 10.27:1
8 9.28±0.02 23.50±4.12 8.34±2.66 91.66±2.66 214.60±7.92 49872.94±1715.15 9.41:1
14 8.26±0.02 14.99±0.39 9.12±1.14 90.88±1.14 510.81±11.32 58608.01±2701.82 7.97:1
36 8.27±0.06 14.36±0.12 9.48±0.13 90.52±0.13 48.75±2.80 32698.26±2378.98 14.13:1
Table 8 Physico-chemical properties of the pig manure during anaerobic stabilization (CM) (DM - dry matter, IM - inorganic mater, OM - organic matter; NH4+ - ammonium ions, Nt - total nitrogen)
Storage
0 8.47±0.58 33.22±6.88 8.09±2.57 91.91±2.57 120.89±7.05 13789.52±2356,62 34.27:1
1 12.97±0.02 41.57±2.46 58.88±17.14 41.12±17.14 69.64±4.28 125901.56±873.31 8.11:1
3 12.76±0.01 45.96±3.72 39.91±7.76 60.09±7.76 111.75±9.84 18866,51±3349.86 16.32:1
8 10.39±0.01 26.91±2.16 16.95±2.67 83.05±2.67 236.01±7.05 52051.28±1482.36 8.17:1
14 8.29±0.01 21.47±5.22 14.36±3.41 85.64±3.41 326.22±17.94 56824.87±2746.13 7.72:1
36 8.29±0.01 20.11±2.32 13.41±1.12 86.19±1.12 225.21±22.47 71771.76±1722.51 6.14:1
Table 9 Physico-chemical properties of the pig manure mixed with dust rejects in a
concentration of 20 g.kg-1 during anaerobic stabilization (M20) (DM - dry matter, IM -
inorganic mater, OM - organic matter; NH4+ - ammonium ions, Nt - total nitrogen)
Storage
0 8.47±0.58 33.22±6.88 8.09±2.57 91.91±2.57 120.89±7.05 13789.52±2356,62 34.27:1
1 12.86±0.03 30.33±3.87 48.90±15.23 51.10±15.23 126.24±9.84 37815.69±1860.53 6.97:1
3 12.96±0.01 37.31±3.89 57.40±5.92 42.60±5.92 130.15±9.01 35790.24±2332.63 6.08:1
8 11.56±0.02 25.37±0.95 48.67±3.35 51.33±3.35 176.67±10.10 81616.08±3704.40 3.21:1
14 9.36±0.01 20.30±2.17 34.12±1.12 65.88±1.12 206.99±17.83 44057.78±2515.94 7.66:1
36 8.76±0.01 20.08±1.56 32.48±3.46 67.52±3.46 181.37±25.75 65746.86±2677.51 5.25:1
Table 10 Physico-chemical properties of the pig manure mixed with quick lime in a
concentration of 20 g.kg-1 during anaerobic stabilization (ML20) (DM - dry matter, IM -
inorganic mater, OM - organic matter; NH4+ - ammonium ions, Nt - total nitrogen, - - not examined)