CHARACTERIZATION OF WASTEWATER SLUDGE IN

OMAN

Dr. Mahad BaawainDept. of Civil & Arch. Eng.

Sultan Qaboos University, Oman

Project Overview

Wastewater & Sludge in Muscat, Salalah & Shoar

Current situation:WW collection,

treatment & disposal

Current situation:Sludge treatment,

handling & disposal

Assess effects (if any) on

environment & human health

Assess quality of resultant sludge &

possibility of producing energy

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Outline

Introduction Objectives Study area Treated effluent applications Basic information Wastewater treatment plants Sampling scheme Results Conclusions

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Introduction

In Oman, wastewater treatment plants use mainly activated sludge process which results in the generation of a large amount of waste activated sludge

The resulted sludge from treatment plants in Oman is disposed in dumping sites

Interest in methods to reuse the resulted sludge instead of dumping it has been growing rapidly

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Objectives

To characterize domestic and industrial wastewater sludge collected from different wastewater treatment plants in Oman

To suggest reuse options for the sludge

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Study Areas

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Treated Effluents Applications

Urban reuse (Irrigation public parks, landscapes, fire protection, etc): Muscat, Salalah

Agricultural reuse (Irrigation of nonfood crops), Salalah

Environmental reuse (Creating artificial wetlands), Muscat

Industrial reuse (Process water & cooling water): Muscat, Sohar, Salalah

Indirect Potable Reuse (Groundwater recharge), Salalah

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Basic Information

WWTP Capacity (m3/d)

TE (m3/d)

Sludge(Ton/d)

Application

Al-Ansab 25,000 21,000 66 Landscaping

Darsait 21,000 18,000 33 Landscaping

Rusayl Ind. 1,200 800 (~2) Landscaping

Rusayl Dom. 300 285 (~0.7) Landscaping

Salalah STP 22,000 20,000 35.5 Recharge wells

Salalah Ponds 3,000 1,500 (~3) Wadi overflow

Raysut Ind. 470 150 (~0.4) Landscaping

Sohar STP 8000 6600 (~15) Landscaping

Sohar Ind. 700 300 (~0.8) Landscaping

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Wastewater Treatment Plants

Grit

Oxygen

RAS

WAS Thickening Dewatering

Sludge to land disposal

Bar Screen & Grit Removal Aeration

Tank

Settling Tank

Filtration Unit

Disinfection

Chlorine Treated Effluent

Balance Tank

Sampling Scheme

Chemical:Anions, Cations,

Physical:(Dry solids, Organic

content)

Biological:Microorganisms

Sludge from settling basins and drying

beds per plant

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Industrial Wastewater Sludge

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The average obtained values of the cations in sludge samples were within the Omani standard for the re-use of sludge in agriculture except for Cd in RSL.IE

By comparing the results to the typical values for metals in biosolids in United Status, all the results are within the typical range except Zn in RIE.

The effect of seasonal change appeared in Cr, Cu, Cd and Zn

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Domestic Wastewater Sludge

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VC

%

Overall avg.SLL.STPSohar.DAnsabDSTRSL.D

85

80

75

70

65

60

55

50

The average obtained values of the cations in the sludge samples were found within the Omani standard for the re-use of sludge in agriculture except for Zn in Sohar.D.

By comparing the results to the typical values for metals in biosolids in United States, all the results are within the typical range except Zn in Ansab and Sohar.D.

The effect of seasonal change appeared at Cu, Pb, Ni and Zn

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Sample Cd Cr Cu Pb Mo Ni Zn

RSL.D 0.21 11.63 302.15 343.05 2.10 66.71 448.57

DST 0.20 7.40 366.43 24.58 10.12 139.76 855.31

Ansab 0.20 1.00 596.70 71.80 14.80 129.40 2161.30

Sohar.D NA NA NA NA NA NA NA

SLL.STP 0.20 1.00 173.80 30.56 6.80 80.48 704.48Overall average 0.20 5.26 359.77 117.50 8.46 104.09 1042.41

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Conclusions

Values of pH 5.8 to 8.0 for industrial sludge and 6.0 to 7.8 for domestic sludge

Most of EC results of industrial sludge were below 1000 µS/cm except that for RIE.

The range of VC in RAS samples was 44 to 86 % in industrial STPs compared with 49.5 to 84.3 % in domestic STPs

Both industrial & domestic STPs show low Fluoride and Bromide concentrations

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Conclusions

Overall average of Nitrite in domestic STPs was higher than industrial STPs

Overall average of Nitrate in industrial STPs was higher than domestic STPs.

Industrial & domestic STPs Chloride, Sulfate & Phosphate higher than other anions

Average cations concentrations were within the Omani standard for the re-use of sludge in agriculture except for Cd in RSL.IE.

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Acknowledgments

Financial support by Sultan Qaboos Univ. Ministry of Regional Municipalities and Water

Resources Minsitry of Environment and Climate Affairs Haya Water, Salalah Sanitary Drainage

Services, & Industrial Estates Technical staff at environmental eng. labs Postgrad & undergrad students for their

effort and enthusiasm during this project

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THANK YOU…

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