**Abbreviations**

Trickling filter: TF Total suspended solids: TSS Chemical oxygen demand: COD Up-flow anaerobic sludge blanket: UASB Anaerobic filter: AF Anaerobic hybrid: AH Biodegradable organic matter: BOM Hydraulic retention time: HRT Organic loading rate: OLR Polyurethane trickling filter: PTF Anaerobic baffled reactor: ABR Volatile suspended solids: VSS

Dissolved oxygen: DO Total Kjeldahl nitrogen: (TKj-N), Thermal conductivity detector: TCD gCOD removed: gCOD R Sludge residence time: SRT Total nitrogen: TN Mixed liquor suspended solids: MLSS Mixed liquor volatile suspended solids: MLVSS Polyvinyl chloride: PVC Influent wastewater: Influent WW anaerobic hybrid effluent: AH-eff. Percentage removal: %R Volatile fatty acids: VFAs Influent expression: Inflow wastewater Effluent expression: Treated wastewater Anaerobic hybrid effluent: AH-eff Polyurethane trickling filter effluent: PTF-eff Scanning electron microscope:SEM Flame ionization detector: FID NOx-N: NO3-N + NO2-N

#### **5. References**

376 Polyurethane

**4. Conclusions** 

discharge.

**Author details** 

*Dokki, Cairo, Egypt* 

**Abbreviations** 

Trickling filter: TF

Anaerobic filter: AF Anaerobic hybrid: AH

Total suspended solids: TSS Chemical oxygen demand: COD

Up-flow anaerobic sludge blanket: UASB

Biodegradable organic matter: BOM Hydraulic retention time: HRT Organic loading rate: OLR Polyurethane trickling filter: PTF Anaerobic baffled reactor: ABR Volatile suspended solids: VSS

**Acknowledgement** 

Ahmed Tawfik

 The results obtained revealed that the combined system (AH+ PTF) is very effective for the treatment of tomato industry wastewater at a total HRT not exceeding 10 h. The total process removed 96% of COD total, 92% of COD soluble, 98% of COD particulate, 85% of TKj-N, 89% of NH4 –N, 97% of TSS, and 98% of VSS. The effluent quality is complying for reuse and /or discharge according to Egyptian standards for

 The experimental results obtained here demonstrated that AHreactor and PTF was capable of operating efficiently at short HRT and high values of OLR in the treatment of tomato industry wastewater. Therefore, the volume of the reactor could be reduced five times in comparison with that used in conventional treatment systems without affecting

The author is very grateful for Prof. M. Salem, Prof. R. Abdel Wahab, Dr. A. Al-Asmer, A.

the organic matter removal and nitrification efficiency.

*Egypt-Japan University of Science and Technology (E-Just); School of Energy Resources and Environmental Engineering,* 

Elmitwalli and Prof. Maei for their support and help.

*National Research Center (NRC), Water Pollution Research Dept.,* 

*New Borg El Arab City, Alexandria, Egypt* 


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**Chapter 17** 

© 2012 Voršič, licensee InTech. This is an open access chapter distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use,

distribution, and reproduction in any medium, provided the original work is properly cited.

© 2012 Voršič, licensee InTech. This is a paper distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

The designers of electro energetic system are thinking, to conserve the routes of 220kV transmission lines, and the transition to 400kV lines. The easiest way seems to be the placement of new overhead power lines. The other option is the use of covered conductors. Covered conductors are conductors with insulation made from two dielectrics: the first is the insulation mantel and the other is air. The covered conductors consist of a conductor which is a metal electrode (a cable), and the covering mantel which is made from a dielectric with a greater dielectric constant and higher breakdown voltage. The other dielectric with a lower dielectric constant is the surrounding air. The conductor should not be touched

According to the usual labelling of conductors, we named the suggested conductor PUAC 2150/490/65 mm2. Here 2150 mm2 stands for the cross section of the polyurethane mantel, 490 mm2 for the aluminium and 65 mm2 for the core made from carbon fibbers. The saved weight (instead of steel we use carbon fibbers) can be used for the insulation. The insulation has to be thick enough so that the electric field intensity on the edge of the insulator does not exceed the critical electric field intensity of air. Such a conductor, hanged on a typical 220 kV transmission tower meets the electric load exerted. Simplified analytical calculations of the electric field intensity on the edge of the insulation match exact calculation, using the finite

element method*.* This fact encourages new research, both theoretical and practical.

**2. The current usage of covered conductors in the middle to high voltage** 

Covered conductors for overhead power lines are meant to replace the existing bare cable power lines, especially in wooden areas where the risk of falling trees is high. Another concern is the weighing down of cables from sticking snow and ice. Reasons for using

**Polyurethane as an Isolation** 

Additional information is available at the end of the chapter

**for Covered Conductors** 

Žiga Voršič

http://dx.doi.org/10.5772/35083

**1. Introduction** 

despite the insulation.

**networks** 

Wu, M.; Wilson, F.; & Tay, J.H.; (2000). Influence of media-packing ratio on performance of anaerobic hybrid reactors. Bioresource Technol., 71, 151–157

**Chapter 17** 
