1. ADF (2015) Ghana—Accra sewerage improvement project (ASIP). Appraisal Report. African Development Fund. http://www.afdb.org/fileadmin/uploads/afdb/Documents/Project-and-Operations/Ghana_-_Accra_Sewerage_Improvement_Project_ASIP_-_Appraisal_Report.pdf . Accessed 8 July 2016
2. Akuffo SB (2001) Wastewater problems in Accra: the tale of two parallel projects. Accra Mail, 31 May. Accra, Ghana. Accessed 18 July 2016
3. Alhija HA (2008) Sewage sludge management in Maryland. Maryland Department of the Environmen’s (MDE). http://mde.maryland.gov/programs/ResearchCenter/ReportsandPublications/Pages/ResearchCenter/publications/general/emde/vol3no7/sewage.aspx . Accessed 30 Nov 2016
4. Ashley K, Cordell D, Mavinic D (2011) A brief history of phosphorus: from the philosopher’s stone to nutrient recovery and reuse. Chemosphere 84(6):737–746. https://doi.org/10.1016/j.chemosphere.2011.03.001
5. AySA (2010) Informe al usuario. Datos a diciembre de 2009. Expansión y desarrollo: trabajamos para el desarrollo y bienestar de la comunidad. Aguas y Sanaemientos, Buenos Aires, Argentina. http://www.aysa.com.ar/Media/archivos/391/Informe_al_Usuario_2009.pdf . Accessed 8 July 2016