This is a practical handbook providing a step-by-step approach to the techniques used for characterizing wastewater sources and investigating sites where collection, treatment and reuse/disposal technologies will be installed. It is intended to help enable local implementation of on-site and decentralized wastewater treatment systems (DEWATS) for wide scale use in development settings.
Designing Wastewater Systems According to Local Conditions helps local service providers and regulatory officials make informed decisions through the use of tools, checklists and case studies. It will include a link to a web based community of on-site and decentralized wastewater professionals, which contains related tools and case studies. This handbook will serve as a reference for training classes, certification programs, and higher education programs in civil and sanitary engineering.
There is an increasing interest on the part of local government officials and private sector service providers to implement wastewater treatment systems to solve sanitation problems. The model presented in this handbook promotes activities that first generate data related to source and site conditions that represent critical inputs, and then applies this information to the technology selection process. Matching the most appropriate technologies to the specific needs of the wastewater project is the key that leads to long term sustainability.
Designing Wastewater Systems According to Local Conditions is an invaluable resource for public sector decision makers and private sector service providers in developing countries. It is also a useful text for students at engineering colleges in developing countries interested in taking a class that teaches the methods of DEWATS development.
- Introduction to on-site and decentralized wastewater treatment and typical components of DEWATS systems. Discusses pre-treatment, primary treatment, secondary treatment, disinfection, reuse and recycling.
- The DEWATS decision model – critical inputs (source and site) and the DEWATS decision-making process.
- Characterizing the Source by determining hydraulic and organic loading; Identifying fluctuations in flow, and identifying other source factors that might impact upon the technology decisions.
- Evaluating the site:
o Drawing the site plan. Includes checklists, setbacks and examples.
o Determining available area for wastewater components.
o Testing the soils for depth, bearing capacity and permeability.
o Discusses percolation testing and soils evaluation as methods for determining permeability.
o Checking the slope and drawing topography.
o Evaluating water resources – groundwater and surface water , and methods for collecting anecdotal information to determine flood plain elevations.
o Understanding the local land-use issues.
o Evaluating social issues related to the site.
- Using Collected Data for DEWATS Decision-making; Case studies, practical exercises, Interfacing with other resources.