Decentralized Wastewater Treatment Systems (DEWATS)

Product Description

DEWATS is a technical approach to decentralized wastewater treatment in developing communities. The passive design uses physical and biological treatment mechanisms such as sedimentation, floatation, aerobic and anaerobic treatment to treat both domestic and industrial wastewater sources. DEWATS is designed to be affordable, low maintenance, use local materials, and meet environmental laws and regulations. DEWATS has service packages available for the sanitation needs of small and medium-sized enterprises including communities, schools, municipalities, agro-industry, emergency settlements, hospitals, hotels, and prisons.

Pricing varies depending on project size. Emergency sanitation costs are approximately 18 USD per user, while the total construction cost of DEWATS for Hospitals is approximately 67,000 USD. Community sized DEWATS has been found to range from 150-300 USD per user.

Target SDGs

SDG 6: Clean Water and Sanitation

Market Suggested Retail Price

$50,000.00

Target Users (Target Impact Group)

Household, Community, Public Sector Agencies

Distributors / Implementing Organizations

This solution is implemented by Bremen Overseas Research & Development Association (BORDA)

Competitive Landscape

Direct competitors include The Biofil Digester and Biopipe.

Manufacturing/Building Method

All materials used for construction are locally available.

Intellectural Property Type

Open-source

User Provision Model

Users can contact BORDA for information on service packages offered for DEWAT solutions.

Distributions to Date Status

As of 2017, more than 750 DEWATS plants were currently operating.

Flow rate (L/min)

0.7 – 700 L/min

Power Supply Type

No power required

Technology type

Sedimentation, Flocculation, Aerobic and Anaerobic treatment

BOD Removal Efficiency

90%

COD removal efficiency

90%

NH4-N Removal Efficiency

70%

TSS removal efficiency

96%

Total Phosphorus Removal Efficiency

26%

Fecal Coliform Removal Efficiency

98%

Design Specifications

The DEWAT functions as follows: 1. Primary treatment involving sedimentation and flotation 2. Secondary anaerobic treatment in fixed-bed reactors: baffled upstream reactors or anaerobic filters 3. Tertiary aerobic treatment in sub-surface flow filters 4. Tertiary aerobic treatment in polishing ponds 5. Systems can be designed to handle organic wastewater flows from 1-1000 m³ per day 6. Systems are built to be tolerant towards fluctuations in loads

Product Schematics

Technical Support

Experienced DEWATS experts facilitate comprehensive training programs for qualified staff of partner organizations and take on a supervisory role during the initial technical implementations.

Replacement Components

Unknown

Lifecycle

Unknown

Manufacturer Specified Performance Parameters

Performance targets for DEWAT technologies are targeted at achieving the following advantages: 1. Providing treatment for domestic and industrial wastewater 2. Low primary investment costs as no imports are needed 3. Efficient treatment of daily wastewater flows up to 1000 m³ 4. Modular design of all components 5. Tolerant towards inflow fluctuations 6. Reliable and long-lasting construction design 7. Expensive and sophisticated maintenance not required 8. Low maintenance costs

Vetted Performance Status

Testing performed to assess the average removal efficiencies for a DEWATS facility in Nepal consisting of an Anaerobic Baffled Reactor and Constructed Wetland: 96% TSS, 90% BOD, 90% COD, 70% NH4-N, 26% Total P, and 98% FC.

Safety

Sludge must be handled, treated and disposed of in accordance with hygiene and environmental standards.

Complementary Technical Systems

DEWATS technical layouts can be optimized to provide a renewable energy source in the form of biogas.

Academic Research and References

Cardona, J., et al., 2010, DEWATS Capacity Building for Primary Schools in Jordan and Palestine, Water Practice and Technology 5 (4).

Kerstens, K.M., et al., 2012, Evaluation of DEWATS in Java, Indonesia, Journal of Water, Sanitation and Hygiene for Development 2 (4): 254–265.

Reynaud, N., Buckley, C., 2015, Field-data on parameters relevant for design, operation and monitoring of communal decentralized wastewater treatment systems (DEWATS), Water Practice and Technology 10 (4): 787–798.

Singh, S., et al., 2009, Performance of an anaerobic baffled reactor and hybrid constructed wetland treating high-strength wastewater in Nepal—A model for DEWATS, Ecological Engineering 35 (5): 654-660.

Jha, A. K., Bajrachraya, T. R., 2014, Wastewater Treatment Technologies in Nepal, Conference: IOE Graduate.

Compliance with regulations

Regulations vary by project location. A case study in Indonesia revealed over 90% of systems tested complied with Indonesian environmental regulations of BOD effluent less than 100 mg/L.

Evaluation methods

DEWAT technologies are evaluated for their capability to provide efficient treatment for domestic and industrial wastewater.

Other Information

Schematics illustrating processes employed by DEWAT systems
Presentation about Decentralised Waste Water Treatment System (DEWATS).
Case study - Review of Community-Managed Decentralized Wastewater Treatment Systems in Indonesia
DEWATS – Sustainable treatment of wastewater at the local level
A Practical Guide - BORDA, WEDC

Comments from the Community

2 Comments

E4C.COMMENTS says:

September 26, 2016 at 2:08 am

Emily says:

$600 is for the entire system. Unclear how many toilets can share a single biodigester. This price isn’t actually per toilet
E4C.COMMENTS says:

September 26, 2016 at 3:14 am

Emily says:

They do not yet process the waste into energy or fertilizer. The municipal waste treatment facility discharges the treated wastewater into the river.