Emerging Management Solutions
Improving Treatment Systems
The development of innovative technologies and improvements to conventional systems offer enhanced methods for treating wastewater. Some of these new management strategies are aimed at increasing treatment efficiency, improving the quality of discharge water, or generating profit from a valuable resource recovered from wastewater.
Improving Septic Systems
Widespread usage of septic systems has resulted in the development of a variety of modifications which address unique treatment needs. These additional treatment steps ensure that the wastewater that enters the environment is cleaner. Since these systems are usually paired with wells as a source of drinking water, this improves the quality of drinking water as well.
Chamber Septic Systems
A chamber system is an alternative to the traditional gravel/stone septic design, which is easier to construct. The drainfield is made up of a series of closed chambers surrounded by soil. Wastewater moves through the septic tank and then into the chambers, where microbes in the soil help to remove pathogens.
Cluster Septic Systems
A cluster or community septic system increases the efficiency of wastewater treatment by combining the wastewater from a group of houses. Each house has its own septic tank providing initial treatment. The effluent comes together and flows through a shared drainfield. These systems work best in rural, growing communities with houses near each other.
Nutrient Reducing Septic Systems
Reducing nutrient loads in local water bodies is a high priority when developing improved wastewater treatment systems. New septic system technologies are increasing the capacity for nutrient removal from effluent prior to discharge. These system improvements are more and more common, and even required in some places that are especially vulnerable to eutrophication. Sand filters, as shown in the diagram below, provide a high level of nutrient removal. They are more expensive than conventional systems but can help mitigate nutrient levels in nearby water bodies.
Aerobic Treatment Units
In places with aquatic ecosystems that are particularly sensitive to nutrient pollution, aerobic treatment units offer a small-scale version of the treatments used at centralized treatment plants. Adding oxygen increases bacterial activity to reduce nutrient levels. Some systems have additional treatment tanks with a disinfection step to remove pathogens.
Resource recovery refers to the capture and reuse of water and solids from human waste. Some strategies for resource recovery include:
- Freshwater reclamation for irrigation and other non-potable uses, which can also reduce water needed for future sanitation and treatment
- Biosolids used to add to soil as fertilizer when treated to appropriate standards (for example, opens in a new windowLoop Biosolids Seattle, USA which uses microbes and heat for digestion to create a product to use in gardens and forests)
- Microfiltration, reverse osmosis, and UV (used by Orange County Water District’s groundwater replenishment system, for drinking water in Los Angeles, USA)
- Biogas generation through anaerobic digestion and methane capture – often employed by large scale wastewater treatment plants (WWTPs) to recover resources, treat biosolids, and mitigate greenhouse gas emissions
Resource recovery is gaining traction as a solution for both small, decentralized systems and large, centralized treatment plants. Benefits of resource recovery strategies include:
- Removing nutrients and contaminants that are hazardous to human and ocean health.
- Recovering valuable resources from waste.
- Can be implemented as a sanitation system where one didn’t exist or improve/replace an outdated treatment system.
Two operations are presented in more detail below, offering examples of container-based and municipal-scale innovations.
In Haiti, the non-governmental organization SOIL (Sustainable Organic Integrated Livelihoods) is applying resource recovery technology to provide container-based sanitation. This system safely provides toilets to those without access and offers a solution to pollution and erosion. Toilets divert urine and isolate solid waste for weekly collection.
SOIL collects and transports waste to a composting facility where it is treated to standards defined by the World Health Organization. The finished fertilizer is sold to farmers to increase their crop yields and reduce erosion.
Ideally, resource recovery creates value from waste through an entirely closed loop system, as exemplified by the Janicki Omni Processor. The Omni Processor takes in human waste and garbage and turns it into electric power and clean drinking water. It works like a steam power plant, an incinerator, and a water filtration system combined into one. Though still a prototype in Dakar, Senegal, the system demonstrates the potential to offset costs associated with operations (since it produces its own energy to run) and natural resource inputs (since sewage and trash are free). Recognizing the high initial costs to build this system, the Omni Processor is a prospective replacement for large scale wastewater treatment plants serving cities around the world.
Natural treatment processes use plants and microbes to break down, absorb, trap, and/or oxygenate pollutants in contaminated water as it moves through the environment. These natural processes effectively capture and filter contaminated surface and groundwater, including polluted runoff from rainfall, before it is discharged into the ocean.
Nature-based solutions include constructed wetlands, bioswales, activated charcoal deposits, settlement ponds, riparian buffer zones, and more. Critics of nature-based solutions claim they may not provide adequate treatment and removal of pathogens. However, an effective strategy to enhance pathogen removal is to ensure that the system provides extended interaction with oxygen and microbes by slowing down flow rates and coupling the nature-based solutions with additional treatment steps from a centralized or decentralized system. These strategies have the added benefit of providing habitat to support biodiversity, supporting recreation (including fishing and tourism), and aesthetic benefits over other treatment technologies.
Explore these two examples for a closer look at natural treatment processes:
- Green infrastructure was used to provide additional treatment to septic tank discharge, enhancing contaminant removal and significantly reducing the volume of wastewater entering Guánica Bay, Puerto Rico.
- Biochar (charcoal produced from organic matter) and vetiver grass were used for erosion control and to remove nutrients in American Samoa.