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Comparative Evaluation of Sludge Reduction Routes

Comparative Evaluation of Sludge Reduction Routes

Philippe Ginestet

(2006)

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Abstract

This project aims at the evaluation of eight various routes that potentially may allow wastewater treatment plants to produce less sludge (from 5% to 100%). It has been possible to define several routes that could be applied efficiently with knowledge of possible side-effects (risk management) and an estimation of associated costs (OPEX/CAPEX), which are quite comparable to those used in conventional sludge treatment and disposal.

Table of Contents

Section Title Page Action Price
Contents 6
1.0 TECHNICAL EVALUATION OF SLUDGE PRODUCTION and REDUCTION 18
RESULTS ON SLUDGE REDUCTION PRODUCTION 21
Predictability of sludge reduction from batch tests 22
Sludge reduction with raw wastewater 24
Sludge reduction with primary settled wastewater 25
Overall sludge reduction with primary settled wastewater but using the whole configuration 27
Comparison between the various configuration (raw wastewater, primary settled wastewater and whole plant with primary settling, activated sludge and digestion). 31
Conclusions on sludge reduction 31
2.0 ENVIRONMENTAL IMPACT OF SLUDGE REDUCTION ROUTES 33
TREATED WATER QUALITY 33
RESIDUAL SLUDGE QUALITY 34
Dewatering 34
Heavy metals 34
Hygienisation 35
OTHER ENVIRONMENTAL ISSUES 35
CONCLUSIONS ON THE ENVIRONMENTAL IMPACT 36
3.0 ECONOMICAL EVALUATION 37
SCOPE OF THE ANALYSIS 37
BASIC HYPOTHESIS 38
SLUDGE PRODUCTION (AMOUNT AND COST) 38
Amount 38
Costs 40
Sludge treatment cost 40
Sludge disposal cost 41
Sludge reduction 41
Additional requirements or savings (oxygen, polymers, final sludge dryness) 42
Oxygen over consumption 42
Amount 42
Cost of oxygen supply 43
Sludge conditioning and disposal 43
Conclusions on additional requirements or savings 45
INVESTMENTS 45
Price of equipments 45
Cost of equipments 45
Depreciation of investments 46
OPERATIONAL EXPENDITURES 46
ENERGETIC COST 47
Reactives costs 48
Manpower costs 48
Cost of maintenance 48
4.1 SCALING UP OF THERMAL ROUTE 50
DESCRIPTION OF THE ROUTE 50
SLUDGE REDUCTION POTENTIAL* 51
CAPITAL EXPENDITURES: CAPEX FOR THE THERMAL ROUTE 51
OPERATIONAL EXPENDITURES: OPEX FOR THE THERMAL ROUTE 51
ECONOMICAL RATIOS FOR THE THERMAL ROUTE 52
4.2 SCALING UP OF MECHANICAL ROUTE 53
DESCRIPTION OF THE ROUTE 53
SLUDGE REDUCTION POTENTIAL 53
CAPITAL EXPENDITURES: CAPEX FOR THE MECHANICAL ROUTE 54
OPERATIONAL EXPENDITURES: OPEX FOR THE MECHANICAL ROUTE 54
ECONOMICAL RATIOS FOR THE MECHANICAL ROUTE 54
4.3 SCALING UP OF ELECTRICAL ROUTE 56
DESCRIPTION OF THE ROUTE 56
SLUDGE REDUCTION POTENTIAL 57
CAPITAL EXPENDITURES: CAPEX FOR THE ELECTRICAL ROUTE 57
OPERATIONAL EXPENDITURES: OPEX FOR THE ELECTRICAL ROUTE 57
ECONOMICAL RATIOS FOR THE ELECTRICAL ROUTE 58
4.4 SCALING UP OF OXIDATIVE ROUTE 59
OXIDATIVE ROUTE USING OZONE 59
Description of the route 59
Sludge reduction potential 60
Capital Expenditures: CAPEX for the ozone route 60
Operational Expenditures: OPEX for the ozone route 60
Economical ratios for the PAM route 60
OXIDATIVE ROUTE USING HYDROGEN PEROXIDE (H2O2) 61
Description of the route 61
Sludge reduction potential 62
Capital Expenditures: CAPEX for the hydrogen peroxide route 62
Operational Expenditures: OPEX for the hydrogen peroxide route 62
Economical ratios for the hydrogen peroxide route 63
4.5 SCALING UP OF UNCOUPLING ROUTE 64
DESCRIPTION OF THE ROUTE 66
Sludge reduction potential 67
Capital Expenditures: CAPEX for the PNP route 67
Operational Expenditures: OPEX for the PNP route 67
Economical ratios for the PNP route 68
PROCESS UNCOUPLING ROUTE: CBR 64
Description of the route 64
Sludge reduction potential 64
Capital Expenditures: CAPEX for the CBR route 65
Operational Expenditures: OPEX for the CBR route 65
Economical ratios for the CBR route 65
CHEMICAL UNCOUPLING ROUTE: PNP 66
4.6 SCALING UP OF PREATION ENHANCEMENT ROUTE 69
DESCRIPTION OF THE ROUTE 69
SLUDGE REDUCTION POTENTIAL 69
CAPITAL EXPENDITURES: CAPEX FOR THE FRONT CHEMOSTAT ROUTE 70
OPERATIONAL EXPENDITURES: OPEX FOR THE FRONT CHEMOSTAT ROUTE 70
ECONOMICAL RATIOS FOR THE FRONT CHEMOSTAT ROUTE 70
ANAEROBIC TREATMENT: ENHANCED SETTLING USING PAM 72
Description of the route 72
Sludge reduction potential 73
Capital Expenditures: CAPEX for the PAM route 73
Operational Expenditures: OPEX for the PAM route 74
Economical ratios for the PAM route 74
4.7 SCALING UP OF ANAEROBIC TREATMENT ROUTE 72
ANAEROBIC TREATMENT: ANAEROBIC FILTER 75
Description of the route 75
Sludge reduction potential 76
Capital Expenditures: CAPEX for the anaerobic filter route 76
Operational Expenditures: OPEX for the anaerobic filter route 77
Economical ratios for the anaerobic filter route 77
5.0 ECONOMICAL COMPARISON OF THE ROUTES 79
INVESTMENTS 79
Capita specific investment (CAPEX/pe) 80
Capita specific CAPEX: general considerations 80
Capita specific CAPEX: results for the routes 80
Capita specific CAPEX: conclusions 81
Sludge destruction specific investment 82
Sludge destruction specific CAPEX: general considerations 82
Sludge destruction specific CAPEX: results for the routes 82
Sludge destruction specific CAPEX: conclusions 85
OPERATIONAL EXPENDITURES 85
ENERGETIC CONSUMPTION 85
Energetic consumption: general considerations 85
Energetic consumption: results of routes 85
Origin of energetic costs 87
Route 88
Thermal 88
Energetic consumption: conclusions 89
Reactives costs 89
Reactive costs: general considerations 89
Reactive costs: results of routes 89
Reactive consumption: conclusion 90
Manpower costs: general considerations 90
Manpower costs: results of routes 90
Manpower cost: conclusions 91
Maintenance costs 91
Direct operating expenditures 92
Global operating expenditures (including depreciation) 95
Description of routes 99
Thermal (p. 48) 100
Mechanical (p. 51) 100
Electrical (p. 54) 100
H2O2 (p. 60) 100
PNP (p. 65) 100
Anaerobic – PAM (p. 71) 100
SLUDGE PRODUCTION (CONTROL) 101
GENERAL CONCLUSION and PERSPECTIVES 99
SLUDGE REDUCTION 101
ENVIRONMENTAL IMPACT 102
ECONOMICAL EVALUATION 103
Bibliographic references 107