Guide for management of waste stabilisation pond systems in South Africa Philip de Souza & Unathi Jack TT 471/10 GUIDE FOR MANAGEMENT OF WASTE STABILISATION POND SYSTEMS IN SOUTH AFRICA Report to the Water Research Commission by Philip de Souza and Unathi Jack on behalf of Emanti Management (Pty) Ltd WRC REPORT NO. TT 471/10 NOVEMBER 2010 Obtainable from Water Research Commission Private Bag X03 Gezina, 0031 The publication of this report emanates from a project entitled Status Quo Assessment of Wastewater Ponding Systems (WRC Project No. K5/1657). DISCLAIMER This report has been reviewed by Water Research Commission (WRC) and approved for publication. Approval does not signify that the contents necessarily reflect the views and policies of the WRC, nor does mention of trade names or commercial products constitute endorsement or recommendation for use. ISBN: 978-1-4312-0034-4 Set No. 978-1-4312-0037-5 Printed in the Republic of South Africa ii EXECUTIVE SUMMARY It is understood that the health of a community is significantly influenced by its water quality. The appropriate management of water systems, both the natural resource and municipal water services, is a critical requirement in municipal services provision. PURPOSE OF THE GUIDE This guide has been developed with the purpose of providing assistance in terms of: Planning for construction of an appropriate wastewater treatment system and determining what is appropriate Management to understand what to expect from the contractors and/or consultants in designing a waste stabilisation ponds system Good operations and maintenance of waste stabilisation ponds system Possible re-use of treated wastewater from waste stabilisation ponds system Upgrading waste stabilisation ponds system. This guide can be used in conjunction with the following Water Research Commission (WRC)/Department of Water Affairs and Forestry (DWAF) guides: DWAF (2004) General Authorisation Permissible Utilisation and Disposal of Treated Sewage Effluent, Department of Health under reference 11/2/5/3: 30 May 1976 “South African water quality guidelines – agricultural use” DWAF 1993 “South African water quality guidelines – industrial use” DWAF 1993 Handbook for the operation of wastewater treatment works (2006) by Frik Schutte All other references at the end of the document A guide for operations and maintenance of waste stabilisation ponds system also developed. WHO SHOULD USE THIS GUIDE? The guide has been developed in such a way that it will assist the wastewater management team to answer the following questions: Is a waste stabilisation pond system appropriate for us? What do we need to consider when designing a waste stabilisation pond system? Once we have constructed a waste stabilisation pond system, how do we operate and maintain the system? Is the treated wastewater in the waste stabilisation pond system suitable for re-use purposes? How do we prevent and respond to typical system failures? What options are available if we need to upgrade or refurbish the waste stabilisation pond system? iii ACKNOWLEDGEMENTS The following persons and organisations are thanked for their contribution to this project. Financial Support Water Research Commission Members of the Reference Team Dr Heidi Snyman Water Research Commission Prof At Pretorius University of Pretoria Dr Paul Gaydon Umgeni Water Mr Andrew Lucas Eastern Cape DWAF Dr Johan van der Merwe Free State DWAF Ms Corrine de Kock Free State DWAF WSAs involved Eastern Cape : Maletswai, Senqu, Buffalo City, Inkwanca, Great Kei Mpumalanga : Emalahleni Free State : Dihlabeng, Kopanong, Letsemeng, Mantsopa, Mohokare, Naledi, Tokologo, Nketoane iv TABLE OF CONTENTS EXECUTIVE SUMMARY ................................................................................................................ iii PURPOSE OF THE GUIDE ........................................................................................................... iii WHO SHOULD USE THIS GUIDE? .............................................................................................. iii ACKNOWLEDGEMENTS .............................................................................................................. iv TABLE OF CONTENTS .................................................................................................................. v LIST OF FIGURES ......................................................................................................................... vi LIST OF TABLES .......................................................................................................................... vii ABBREVIATIONS ........................................................................................................................ viii 1. BASIC CONSIDERATIONS FOR DESIGN OF A WASTEWATER TREATMENT WORKS ................................................................................................................................... 1 2. SELECTING AN APPROPRIATE WASTEWATER TREATMENT SYSTEM ........................ 3 2.1 Wastewater treatment facility efficiency ............................................................................. 3 2.2 Wastewater treatment facilities economic considerations .................................................. 5 2.3 Indicative operations and maintenance cost .................................................................... 14 3. TYPES OF WASTE STABILISATION PONDS..................................................................... 16 3.1 Anaerobic ponds ............................................................................................................... 18 3.2 Facultative ponds ............................................................................................................. 18 3.3 Aerobic ponds ................................................................................................................... 18 4. WASTE STABILISATION PONDS DESIGN CONSIDERATIONS ....................................... 20 4.1 Pond lining ........................................................................................................................ 20 4.2 Pond shape and depth ..................................................................................................... 21 4.3 Pond topography .............................................................................................................. 23 4.4 Pond inlet and outlet ......................................................................................................... 23 4.5 Pond hydraulic considerations.......................................................................................... 24 4.6 Pond location .................................................................................................................... 26 4.7 General ............................................................................................................................. 26 5. MANAGEMENT OF TREATED EFFLUENT ......................................................................... 27 5.1 Environmental consideration ............................................................................................ 27 5.2 Agriculture ......................................................................................................................... 29 5.3 Industrial use of treated wastewater ................................................................................. 30 6. TYPICAL FAILURES AND TROUBLESHOOTING .............................................................. 31 Causes of failing waste water ponds and possible remedial actions ........................................ 31 6.1 Lining ................................................................................................................................ 31 6.2 Inlets and outlets .............................................................................................................. 32 6.3 Receiving ponds ............................................................................................................... 33 6.4 Fencing ............................................................................................................................. 34 6.5 Supervision and Maintenance .......................................................................................... 34 6.6 Algal removal .................................................................................................................... 34 6.7 Odour control .................................................................................................................... 36 6.8 Handling excess flows ...................................................................................................... 36 6.9 Process controllers health ................................................................................................ 37 6.10 Environmental Safety: Monitoring and evaluation of pond system performance ............ 38 7. UPGRADING PONDS ........................................................................................................... 39 7.1 Additional technologies used to improve ponds ............................................................... 39 REFERENCES .............................................................................................................................. 42 APPENDIX A ................................................................................................................................. 44 APPENDIX B ................................................................................................................................