Small, rural sewage works are often scaled-down versions of larger works. Automation, combined with remote visibility, has helped to improve effluent quality compliance and reduce site visit frequencies but the unit cost of treatment is high and reliability remains a concern. A fundamental review is required to explore an alternative approach for such works. This document provides a basis for discussion to enable a project scope, priorities and boundaries to be established.
Unit costs of treatment at small rural sewage treatment works are high, performance and reliability variable and current practice unsustainable. A new design concept for small rural sewage works is therefore required which:
- Is not reliant on mains electricity (or has the resilience to maintain compliance during power outages);
- Provides effective, reliable and sustainable sewage treatment, able to comply with current and anticipated future consent conditions;
- Requires reduced operations and maintenance input;
- Incorporates sustainable sludge handing / treatment processes, reducing or eliminating the requirement for frequent sludge tankering from site;
- Has a lower unit cost of treatment than existing small sewage treatments works.
- An alternative, 'low-tech' approach to small rural sewage works design provides an opportunity to reduce operations, maintenance and sludge removal activities and associated costs;
- Novel, commercially available technologies offer an opportunity to make small, rural sewage treatment works more resilient, reducing site visit frequency and the risk of non-compliance;
- Utilising the latest sensor technology provides an opportunity to improve remote monitoring of rural sewage treatment works, further reducing frequency of site visits;
- Commercially available off-grid power systems, (e.g. micro-wind turbines and solar PV) offer an opportunity to power instrumentation, telemetry systems and small pumps.
PROPOSED PROJECT ACTIVITIES
The suggested scope for this project is outlined below:
- Undertake a review of emerging technologies and related case studies to identify potentially suitable low-tech solutions for small rural sewage treatment works;
- Review novel, commercially available processes that offer the potential to replace, or be retrofitted to traditional wastewater / sludge treatment processes at small, rural sites to provide improved resilience, performance or reduced visit frequency / costs;
- Use modelling techniques to test the performance potential of low tech processes;
- Use outputs from the above tasks to inform the development of a new design concept for small rural sewage treatment works;
- Undertake pilot scale trials to demonstrate the effectiveness, resilience and constraints / issues for the most promising technologies.
A new design concept e-manual and process selection guide for small, rural sewage treatment works that provides improved resilience, performance or reduced visit frequency / costs.
- Focus on novel, emerging and/or commercially available technologies that can replace or be retrofitted to traditional wastewater / sludge treatment processes at small, rural sites;
- Examples of emerging technologies to include:
- Modular reed bed / tertiary filter systems;
- Low sludge production / sludge volume reduction systems;
- Off-grid, power systems for instrumentation, telemetry outstations etc.;
- Cost effective sensors, CCTV and telemetry technology.