Table 1
Parameters tested in the samples, and regulations defining the method of making the assays
| Parameter/Indicator | Regulation specifying the method and procedure for chemical analysis |
|---|---|
| pH | PN-EN ISO 10390:2022-09 |
| total alkalinity | PN-90/C-04540.02 |
| BOD5 | PN-EN ISO 5815-1:2019-12 |
| COD (total and dissolved) | PN-ISO 15705:2005 PN-ISO 6060:2006 |
| forms of nitrogen (total nitrogen, total Kjeldahl nitrogen, ammoniacal nitrogen, nitrite nitrogen, and nitrate nitrogen), | PN-EN 25663:2001 PN-ISO 7150-1:2002 PN-EN ISO 13395:2001 PN-82/C-04576/08 |
| total phosphorus | PN-EN ISO 6878:2006 |
| total suspended solids | PN-EN 872 |
Figure 1.
Diagram of the treatment plant at roadside rest area “A” 1- inlet, 2- outlet, 3- settling tank and retention and averaging buffer, 4- SBR reactor, 5- compressed air inlet, 6- aeration disc, 7- drainage bed (own elaboration)
Figure 2.
Diagram of biological reactor at roadside rest area “B” and “C”: 1- concrete tank, 2- biological bed, 3- effluent filter, 4- effluent outlet, 5- secondary sludge outlet, 6- settling tank wastewater inlet, 7- recirculating device, 8- air duct protection pipe, 9- aluminium lid (own elaboration)
Table 2
Technical parameters of discussed plants
| Installation technical parameters | Rest Area „A” | Rest Area „B” | Rest Area „C” | |||
|---|---|---|---|---|---|---|
| L | R | L | R | L | R | |
| Projected inflow | 5.00 m3/d | 8.00 m3/d | 8.00 m3/d | |||
| Average real inflow | 6.25 m3/d | 3.35 m3/d | 3.80 m3/d | |||
| Volume of primary settling tank | 3.30 m3 | 6.70 m3 | 7.20 m3 | |||
| Reactor volume | 3.30 m3 | 5.65 m3 | 5.95 m3 | |||
| Projected retention time | >15 h | >17 h | >17 h | |||
Table 3
The results of analytical tests of raw wastewater at the roadside rest areas studied (own elaboration)*
| No. | Indicative measure | Unit | Raw wastewater – average values (range of results) | |||||
|---|---|---|---|---|---|---|---|---|
| Rest Area „A” | Rest Area „B” | Rest Area „C” | ||||||
| L | R | L | R | L | R | |||
| 1 | Reaction (PH) | - | 7.9–8.0 | 7.8–7.9 | 8.6–8.8 | 8.2–8.4 | 8.5–8.6 | 8.5–8.8 |
| 2 | Total alkalinity | mval/L | 12.5 | 19.9 | 20.7 | 20.2 | 23.4 | 19.0 |
| 3 | BOD5 | mgO2/L | 180 (176–184) | 162 (155–169) | 400 (393–407) | 497 (480–514) | 191 (189–193) | 160 (153–167) |
| 4 | COD | mgO2/L | 771 (765–777) | 629 (600–658) | 1031 (950–11 12) | 1020 (978- 1062) | 349 (324–394) | 384 (381–407) |
| 5 | COD/ BOD5 | - | 4.3 | 3.9 | 2.6 | 2.1 | 1.8 | 2.4 |
| 6 | BOD5/n | mgO2/mgN | 1.5 | 0.8 | 1.5 | 1.7 | 0.8 | 0.7 |
| 7 | Total Kjeldahl nitrogen | mgN/L | 123 | 201 | 265 | 298 | 232 | 228 |
| 8 | Ammoniacal nitrogen | mgN/L | 103 | 167 | 253 | 252 | 194 | 206 |
| 9 | Total phosphorus | mgP/L | 17.4 (16.5–18.3) | 15.6 (14.9–16.3) | 15.3 (14.9–15.7) | 32.2j (30.1–34.3) | 18.1 (18.0–18.2) | 17.1 (16.2–18.0) |
| 10 | Total suspended solids | mg/L | 280 | 188 | 284 | 252 | 172 | 152 |
Table 4
Analytical results for treated wastewater at the roadside rest areas studied (own elaboration)*
| No. | Indicative measure | Unit | Treated wastewater – average values | Treated wastewater - the standard ** | |||||
|---|---|---|---|---|---|---|---|---|---|
| Rest Area „A” | Rest Area „B” | Rest Area „C” | |||||||
| L | R | L | R | L | R | ||||
| Average value; range of results; percentage of removal [%] | |||||||||
| 1 | Reaction (pH) | - | 7.4–7.5 | 7.3–7.5 | 7.7–7.8 | 7.6–7.8 | 8.3–8.4 | 8.4–8.5 | - |
| 2 | Total alkalinity | mval/L | 4.4 | 3.4 | 8.3 | 5.2 | 22.0 | 18.4 | - |
| 3 | BOD5 | mgO2/L | 13.8; 15.5–14.1; 92.3 | 16.0; 15.3–16.7; 90.1 | 72.0; 71.4–72.6; 82.0 | 81.0; 77–85; 83.7 | 40.0; 38.9–41.1; 79.0 | 86.0; 82.7–89.3; 46.0 | 40 |
| 4 | COD total | mgO2/L | 145; 143–147; 81.2 | 194; 193–195; 69.2 | 306; 293–319; 70.3 | 463; 460–466; 54.6 | 173; 171–175; 50.4 | 208; 205–211; 45.7 | 150 |
| 5 | COD dissolved | mgO2/L | 126 | 166 | 263 | 395 | 144 | 179 | - |
| 6 | Total nitrogen | mgN/L | 59.7 | 120 | 196 | 236 | 232 | 202 | - |
| 7 | Kjeldahl nitrogen | mgN/L | 38.0; 69.1 | 41.4; 79.4 | 138; 47.9 | 141; 52.7 | 249; - | 195; 14.7 | - |
| 8 | Nitrate nitrogen | mgN-NO3/L | 1.7 | 4.4 | 3.6 | 41.9 | 0.37 | 0.49 | - |
| 9 | Nitrite nitrogen | mgN-NO2/L | 20.1 | 74.1 | 55.4 | 52.7 | 6.8 | 6.9 | - |
| 10 | Ammoniacal nitrogen | mgN/L | 24.9; 75.8 | 31.6; 81.1 | 132; 47.8 | 111; 56.0 | 162; 16.5 | 148; 28.2 | - |
| 11 | Total phosphorus | mgP/L | 11.0; 10.7–11.3; 36.6 | 12.5; 12.4–12.6; 19.8 | 16.6; 15.3–17.9; 44.5 | 18.8; 17.3–20.3; 41.6 | 20.1; 15.3– 24.9; - | 18.2; 18.1–18.3; | - |
| 12 | Total suspended solids | mg/L | 29.0; 89.7 | 25.0, 86.7 | 23.0; 91.9 | 191.0; 24.2 | 63.0; 63.5 | 31.0; 79.3 | 50 |
Figure 3.
Average hydraulic load of the wastewater treatment plant at rest area “A” in consecutive months of operation (own elaboration)
Figure 4.
Distribution of dissolved oxygen concentration in the wastewater treatment plant at rest area “C” during successive hours of operation (own elaboration)