13 Salinity, Sanitation and Sustainability: A Study in Environmental Biotechnology and Integrated Wastewater Beneficiation in South Africa Salinity, Salinity, Sanitation and Sustainability: Report 13 Recovery and Re-use of Domestic Wastewaters Using Integrated Algal Ponding Systems: A Key Strategy in Sustainable Sanitation SJ Horan, MP Horan, NG Mohale, KJ Whittington-Jones and PD Rose WRC Report No TT 390/09 W a t e r R e s e a r c h C o m m i s s i o n Private Bag X03, Gezina 0031, South Africa 13 Tel: +27 12 330 0340, Fax: +27 12 331 2565 Web: http://www.wrc.org.za Water Research Commission REPORTS in the WATER RESEARCH COMMISSION PROJECT SERIES SALINITY, SANITATION and SUSTAINABILITY A Study in Environmental Biotechnology and Integrated Wastewater Beneficiation in South Africa Report 1: Volume 1 - Overview Report 7: Volume 3 - Integrated Algal 7 Ponding Systems and the Treatment 1 of Domestic and Industrial Wastewaters Part 4: System Performance and Tertiary Treatment Operations Report 2: Volume 2 - Integrated Algal Report 8: Volume 3 - Integrated Algal 8 Ponding Systems and the Treatment 2 Ponding Systems and the Treatment of Saline Wastewaters of Domestic and Industrial Wastewaters Part 1: Meso-Saline Wastewaters Part 5: Winery and Distillery Wastewaters The Spirulina Model Report 3: Volume 2 - Integrated Algal Report 9: Volume 4 - The Rhodes BioSURE Process ® 3 Ponding Systems and the Treatment 9 of Saline Wastewaters Part 1: Biodesalination of Mine Drainage Wastewaters Part 2: Hyper-Saline Wastewaters The Dunaliella Model Report 10: Volume 4 - The Rhodes Report 4: Volume 3 - Integrated Algal ® 4 Ponding Systems and the Treatment 10 BioSURE Process of Domestic and Industrial Wastewaters Part 2: Enhanced Hydrolysis of Organic Carbon Substrates - Part 1: The AIWPS Model Development of the Recycling Sludge Bed Reactor Report 11: Volume 4 - The Rhodes Report 5: Volume 3 - Integrated Algal ® 5 Ponding Systems and the Treatment 11 BioSURE Process of Domestic and Industrial Wastewaters Part 3: Sulphur Production and Metal Removal Unit Operations Part 2: Abattoir Wastewaters Report 6: Volume 3 - Integrated Algal Report 12: Volume 4 - The Rhodes 6 Ponding Systems and the Treatment 12 BioSURE Process ® of Domestic and Industrial Wastewaters Part 4: Treatment and Disposal Part 3A: Mine Drainage Wastewaters of Sewage Sludges The ASPAM Model Report 6B: Volume 3 - Integrated Algal Report 13: Recovery and Re-use of 6B Ponding Systems and the Treatment 13 Domestic Wastewaters Using Integrated of Domestic and Industrial Wastewaters Algal Ponding Systems: A Key Strategy in Sustainable Sanitation Part 3B: Sulphate Saline Systems: Development of the ASPAM Process Report 6C: Volume 3 - Integrated Algal 6C Ponding Systems and the Treatment of Domestic and Industrial Wastewaters Part 3C: Chloride Saline Systems: The Use of Saline Waters for the Reticulation and Treatment of Domestic and Industrial Effluents SALINITY, SANITATION and SUSTAINABILITY Biotechnology of Saline and Sewage Wastewater Report 14: Volume 1 - Integrated Report 15: Volume 2 - Integrated Beneficiation 14 Physical, Chemical and Biological 15 of Mine Wastewaters Process Kinetic Models for Anaerobic Digestion of Primary Sewage Sludge Cover Photograph: Flamingoes on tannery wastewater ponds at Mossop Western Leathers Co., Wellington, South Africa. The presence of Phoenicopteridae, including both the Greater and Lesser Flamingo, is an important indicator of healthy and naturally functioning saline aquatic ecosystems. This flock occupied the ponding system shortly after commissioning the novel Spirulina-based Integrated Algal Ponding System which had been developed for the treatment of tannery wastewaters. This apparent seal of environmental approval became an icon for the studies which followed in this series. Photograph by Roger Rowswell, whose observation of this system, over a number of years, was instrumental in the initiation of these studies. RECOVERY AND RE-USE OF DOMESTIC WASTEWATERS USING INTEGRATED ALGAL PONDING SYSTEMS: A KEY STRATEGY IN SUSTAINABLE SANITATION Report to the Water Research Commission by S J Horan, M P Horan, NG Mohale, KJ Whittington-Jones and PD Rose on behalf of Environmental Biotechnology Research Unit Rhodes University Grahamstown WRC Report No. TT 390/09 APRIL 2009 Obtainable from: Water Research Commission Private Bag X03 Gezina, Pretoria 0031, South Africa [email protected] The publication of this report emanates from a project entitled: “IAPS Algal Biomass and Treated Effluent Utilisation as a Key Strategy in Sustainable and Low-Cost Sanitation” (WRC Project No. K5/1619). DISCLAIMER This report has been reviewed by the Water Research Commission and approved for publication. Approval does not signify that the contents necessarily reflect the views and policies of the Water Research Commission, nor does mention of trade names or commercial products constitute endorsement or recommendation for use. ISBN 978-1-77005-827-9 Set No. 978-1-86845-853-9 Printed in the Republic of South Africa EXECUTIVE SUMMARY 1. BACKGROUND The degradation of water resources through ineffective and insufficient wastewater treatment has substantial social and environmental impacts. However, this also has direct economic effects which jeopardise the sustainability of future development in water-scarce countries such as South Africa. Poorly treated water is a major contributor to water pollution with elevated oxygen demand, and nutrient and bacterial loadings, leading to eutrophication and destabilisation of important aquatic ecosystems (Horan, 1990). An investigation of the status of small sewage treatment works (STW) in the Eastern Cape (designed to treat less than 1Ml.day-1) showed that these were largely poorly operated and inadequately monitored leading to the release of undertreated effluent into the environment. Lack of maintenance of infrastructure, inadequate operator skills, insufficient monitoring capacity and insufficient forward planning were cited as reasons for poor performance (Antrobus, 2002). A subsequent study by Snyman et al (2006) confirmed that a similar situation applied throughout South Africa and indicated that immediate intervention was necessary for 30% of STWs in South Africa to avoid crisis situations, such as the outbreak of waterborne diseases, and a further 66% required intervention in the short to medium term. The consequences of the situation have been borne out in the tragic loss of life in Delmas in 2006 and elsewhere (Graham, 2006; DWAF, 2003) due to gastrointestinal infections. 2. THE INDEPENDENT HIGH RATE ALGAL POND The Integrated Algal Ponding System (IAPS) has been intensively studied as a low-cost appropriate sewage treatment technology (Rose et al, 2002). In a 9-year study of the system at the Environmental Biotechnology Research Unit (EBRU) at Rhodes University, the High Rate Algal Pond (HRAP), as a component unit operation of the IAPS, was found to be effective as a stand-alone unit for the tertiary treatment of wastewater, particularly where primary and secondary treatment was not achieving required standards for effluent disposal (Wells, 2005). The Independent HRAP (IHRAP), as it became known, was shown to be particularly effective in the disinfection functions of tertiary treatment and could consistently produce water with E. coli counts of <1CFU.100ml-1. In this way the use of chlorine, ozone or other chemical disinfectant treatments are obviated. In addition to effective disinfection, ammonia and phosphate levels were also reduced below discharge standards at 1.4 mg.l-1 and 2.3 mg.l-1 respectively (Wells & Rose, 2006; Wells, 2005). It has been proposed that the IHRAP would provide a low-cost intervention that could be applied immediately as a ‘firewall’ barrier between existing, poorly performing sewage works and the receiving environment. This could enable treatment plants to meet discharge standards and deal effectively with the substantial public health threats both rapidly and at extremely low cost. 3. ALGAL BIOMASS UTILISATION IN HORTICULTURAL APPLICATIONS Algal biomass is produced as a by-product of the IHRAP treatment process and substantial literature exists on the use of various algal types (including macrophytic algae such as kelp i sea weed) as a source of fertiliser and plant growth stimulant applications in horticulture (Arthur et al, 2003; Donelan, 1988; Metting, 1988; Senn, 1987; Featonby-Smith and Van Staden, 1983). In addition to NPK and minerals, algal extracts are thought to provide plant hormones such as auxins and cytokinins, as well as chelating functions (Kelpak, 2005; Davis, 2004; SeaGro Superkel pamphlet, 2004; Arthur et al, 2003; Zhang and Schmit, 2000; Zhang, 1997; Crouch and Van Staden, 1993a; Borowitska, 1988; Donelan, 1988; Senn, 1987). The potential use of algal biomass produced in the IHRAP treating sewage wastewaters for use in plant growth stimulation applications was investigated in the studies reported here. Where this would be shown to be a useful plant fertiliser, the combination of a well-treated and disinfected water, with the biomass recovery as a fertiliser, could provide the basic inputs for the development of a horticultural enterprise and sustainability in wastewater treatment operations. Laboratory and field trials in algal biomass recovery and its use in nutrient enrichment in horticultural applications thus formed the focus of WRC Project K5/1619. Algal biomass was harvested from the pilot-scale IHRAP at EBRU in Grahamstown, treating domestic wastewater. Laboratory-based