**3.4. Efficiency of the combined system (AH+PTF) treating tomato industry wastewater at different OLRs and HRTs**

The results presented in Table 2 revealed that decreasing the total HRT from 14 to 10 h was not significantly affected on the removal efficiency of COD fractions (COD total, COD soluble

and COD particulate). However, decreasing the total HRT from 10 to 7.2 exerted a negative impact on the removal efficiency of the total process as shown in Table 2.

Polyurethane Trickling Filter in Combination with

Anaerobic Hybrid Reactor for Treatment of Tomato Industry Wastewater 371

(c)

(d)

**Figure 9.** (a) DO concentration along the height of PTF reactor treating AH reactor effluent; (b) COD total removal efficiency along the height of PTF reactor treating AH reactor effluent; (c) COD soluble removal efficiency along the height of PTF reactor treating AH reactor effluent; (d) COD particulate removal efficiency along the height of PTF reactor treating AH reactor effluent

#### (a)

and COD particulate). However, decreasing the total HRT from 10 to 7.2 exerted a negative

(a)

(b)

impact on the removal efficiency of the total process as shown in Table 2.

(c)

<sup>(</sup>d)

**Figure 9.** (a) DO concentration along the height of PTF reactor treating AH reactor effluent; (b) COD total removal efficiency along the height of PTF reactor treating AH reactor effluent; (c) COD soluble removal efficiency along the height of PTF reactor treating AH reactor effluent; (d) COD particulate removal efficiency along the height of PTF reactor treating AH reactor effluent

Polyurethane Trickling Filter in Combination with

Anaerobic Hybrid Reactor for Treatment of Tomato Industry Wastewater 373

(a)

(b)

(a)

#### (b)

**Figure 10.** (a) TSS removal efficiency along the height of PTF reactor treating AH reactor effluent; (b) VSS removal efficiency along the height of PTF reactor treating AH reactor effluent

(a)

(b)

**Figure 10.** (a) TSS removal efficiency along the height of PTF reactor treating AH reactor effluent;

(b) VSS removal efficiency along the height of PTF reactor treating AH reactor effluent

(a)

Polyurethane Trickling Filter in Combination with

Anaerobic Hybrid Reactor for Treatment of Tomato Industry Wastewater 375

96±2 92±3.5 98±2.4 85±6 88.6±6.5 - 97±1.2 98±0.5

95±2.2 91±3 97.4±2.6 83±5.3 88.9±5.2 - 96±1.4 96.5±2

88.7±3.3 76±9.1 92±6 36.3±9 21.2±9.4 - 92.1±2.3 91.3±2.5

Parameters COD fractions ( mg/l) Nitrogen species (mg/l) Solids (mg/l) **Run 1** Total Soluble Particulate TKj-N NH4-N NOx-N TSS VSS Wastewater 999.7±337 388±157 612±309 33±6 24.3±5 - 416±95 344±37 AH- effluent 267±48 121.4±40 145±59 28±6 26±5 - 98±23 77±14 PTF- effluent 34.7±8.5 27.4±4.7 7.3±7 4.8±2 2.7±1.4 18±3.6 12.2±3.2 8±1.4

Wastewater 883±285 344±65 539±267 33±5.7 26.1±5.4 - 437.2±160 266±79 AH- effluent 248±61 118±11 131±65 28.4±6 28±6 - 100.3±18 77±18 PTF- effluent 40±8.5 31±6 10±7 6±1.8 2.8±1.3 17.1±4.5 13±2.8 8.3±2

Wastewater 795±168.4 223±59 572±193 32.3±5 23±4.6 - 387.4±48 300±65 AH- effluent 377±89 134.5±23 242.8±89 26±5 24±4.6 - 143.2±17.7 124±12 PTF- effluent 86±16 49.7±10.7 36±23 21±4 17.8±3.7 1.7±0.9 30±5 25±5

**Table 2.** Overall removal efficiencies of the total process ( AH + PTF) treating tomato industry wastewater

Typical SEM images of porous polyurethane of PTF reactor are shown in Fig. 12. Microorganisms were attached to the porous polyurethane packing material (Fig. 12). The presence of microorganisms in the PTF not only oxidizes ammonia, but also improves the

 **Figure 12.** SEM photographs of the microorganisms forming the biofilm in the bioreactor. (a) The clean polyurethane media before attachment of microorganisms; (b) the same surface of the polyurethane

**3.5. Scanning electronic microscope (SEM) observation** 

adsorbent and oxidization capability of e organic matter in the wastewater.

Overall removal

Overall removal

Overall removal

after the attachment of microorganisms.

efficiency

efficiency

efficiency

**Run 3**

**Run 2**

**Figure 11.** (a) NH4-N removal efficiency along the height of PTF reactor treating AH reactor effluent; (b) NOx –N production along the height of PTF reactor treating AH reactor effluent; (c) TKj-N removal efficiency along the height of PTF reactor treating AH reactor effluent

At a total HRT of 14 and 10 h, the combined system (AH+PTF) provided an overall removal efficiencies of 96±2% and 95±2.2% for COD total, 92±3.5% and 91±3% for COD soluble and 98±2.4% and 97.4±2.6 for COD particulate respectively. The overall removal efficiency of COD fractions was dropped at a total HRT of 7.2 h., i.e. 88.7±3.3% for COD total; 76±9.1% for COD soluble and 92±6% for COD particulate. The major part of TSS and VSS was removed in the AH reactor, and little additional removal occurred in the PTF system (Table 2).

The total process achieved an overall removal efficiency of 97±1.2%; 96±1.4% and 92.1±2.3% for TSS at total HRTs of 14, 10 and 7.2 h, respectively. The available data indicates that unique contributions of each technology component to the efficiency of the total treatment system i.e. AH reactor was effective for removal of COD fractions (COD total, COD soluble and COD particulate), TSS and VSS . By capturing the COD and suspended particles early in the AH process, most of the volatile and oxygen-demanding organic matters were removed in PTF (Table 2).

The removal of COD total and TSS in the AH reactor, improved the nitrification efficiency in PTF as shown in Table 2. This is particularly important in food industry wastewater treatment systems because as shown in Table 2, the effluent after AH system contained significant amounts of TKj-N (28 mg/l), mostly soluble forms of NH4-N (26 mg/l). The NH4 –N was efficiently oxidized in the PTF module resulting a removal efficiency of 86±6.5% .


**Table 2.** Overall removal efficiencies of the total process ( AH + PTF) treating tomato industry wastewater

#### **3.5. Scanning electronic microscope (SEM) observation**

374 Polyurethane

(Table 2).

86±6.5% .

(c) **Figure 11.** (a) NH4-N removal efficiency along the height of PTF reactor treating AH reactor effluent; (b) NOx –N production along the height of PTF reactor treating AH reactor effluent; (c) TKj-N removal

At a total HRT of 14 and 10 h, the combined system (AH+PTF) provided an overall removal efficiencies of 96±2% and 95±2.2% for COD total, 92±3.5% and 91±3% for COD soluble and 98±2.4% and 97.4±2.6 for COD particulate respectively. The overall removal efficiency of COD fractions was dropped at a total HRT of 7.2 h., i.e. 88.7±3.3% for COD total; 76±9.1% for COD soluble and 92±6% for COD particulate. The major part of TSS and VSS was removed in the AH

The total process achieved an overall removal efficiency of 97±1.2%; 96±1.4% and 92.1±2.3% for TSS at total HRTs of 14, 10 and 7.2 h, respectively. The available data indicates that unique contributions of each technology component to the efficiency of the total treatment system i.e. AH reactor was effective for removal of COD fractions (COD total, COD soluble and COD particulate), TSS and VSS . By capturing the COD and suspended particles early in the AH process, most of the volatile and oxygen-demanding organic matters were removed in PTF

The removal of COD total and TSS in the AH reactor, improved the nitrification efficiency in PTF as shown in Table 2. This is particularly important in food industry wastewater treatment systems because as shown in Table 2, the effluent after AH system contained significant amounts of TKj-N (28 mg/l), mostly soluble forms of NH4-N (26 mg/l). The NH4 –N was efficiently oxidized in the PTF module resulting a removal efficiency of

efficiency along the height of PTF reactor treating AH reactor effluent

reactor, and little additional removal occurred in the PTF system (Table 2).

Typical SEM images of porous polyurethane of PTF reactor are shown in Fig. 12. Microorganisms were attached to the porous polyurethane packing material (Fig. 12). The presence of microorganisms in the PTF not only oxidizes ammonia, but also improves the adsorbent and oxidization capability of e organic matter in the wastewater.

**Figure 12.** SEM photographs of the microorganisms forming the biofilm in the bioreactor. (a) The clean polyurethane media before attachment of microorganisms; (b) the same surface of the polyurethane after the attachment of microorganisms.
