February 2, 2018 Demonstration Facilities for “Treatment Performance Improvement Technology of Final Settling Tank” (B-DASH 2017) Completed

Japan Sewage Works Agency (JS) has been joining a collaborative research, “Treatment Performance Improvement of Final Settling Tank.” The consortium of Metawater Co., Ltd.; JS; and Matsumoto City implements the demonstration adopted for B-DASH Project*¹ 2017 as contract research of National Institute for Land and Infrastructure Management (NILIM.)
The technology adopts a “filtration unit inside a final settling tank” set in just before its tank drain to trap solid matter of treated water in the tank. The filtration unit enhances the quantitative and qualitative performances of a final settling tank while requiring no additional facilities. The promising technology is expected to contribute the efficient retrofit adapting to the social needs of population decline, and the stable performance for wastewater treatment.
The verified performances in the demonstration are as follows:
(1) Quantity improvement: verify if the technology can increase the treatment quantity of a final settling tank up to twice with no quality degradation of treated water.
(2) Quality improvement: verify if the technology can improve the quality of effluent of a final settling tank equivalent to the effluent of rapid sand filtration when operated at designed treatment quantity.
Compared to the additional final settling tank or filtering facilities, the demonstration technology is expected to reduce construction costs dramatically.
The construction of the demonstration facilities starting in July 2017 has recently completed.

• Final settling tank with a filtration unit
  → Prevent degradation of water quality by increasing treatment capacity, improve the quality of treated water
• Carrier washing with air
  → Require no drain, enable continuous operation
• No submerged motor
  → Easy O&M

Goal

(1) Quantitative improvement
Increase treatment capacity with no degradation of treated water quality
⇒Without additional train:

• Solve the temporary performance degradation of final settling tank when retrofitting
• Adapt to the temporary increase of treatment quantity by the unification of WWTPs/trains

(2) Qualitative improvement
Improve the quality of effluent of a final settling tank equivalent to the effluent of rapid sand filtration when operated at designed treatment quantity.⇒Prevent the temporary degradation of treated water, improve and stabilize the normal quality of discharged water

Expected effects

Derive a calculation formula of the surface settling velocity by the settleability test at the final settling tank
⇒
Create criteria to estimate the effect of quantitative improvement using the surface settling velocity of each municipal WWTP

Demonstration Facilities Overview

• Treatment Capacity: 10,950m3/day: Demonstration facilities are set inside one of three final settling tank trains
• Treatment method: Conventional Activated Sludge Process

*1: B-DASH Project (Breakthrough by Dynamic Approach in Sewage High Technology Project) has been conducted by Ministry of Land, Infrastructure, Transport, and Tourism (MLIT) of Japan. The Project aims to accelerate R&D of new technologies and their practical applications, enhance costs reduction in sewage works and the production of renewable energy, and facilitate the global presence of Japanese companies in their water business.