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Solutions for Industrial Water Treatment

Waste water Treatment

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Overview

Waste water Treatment image

Conventional waste water treatment systems mainly carry out treatment by using aerobic microorganisms.
However, aerobic treatment incurs high costs to treat high-concentration organic waste water discharged from food processing and other plants.

Toshiba has adopted a methane fermentation reactor using anaerobic microorganisms, which takes advantage of the excellent properties of the methane fermentation process to efficiently treat high-concentration organic waste water and realizes environmentally friendly and economical treatment.

Waste water Treatment System for a Starch Factory

Overview

Waste water from starch factories is characterized by a high organic matter load and seasonal factory operations. After a low-pressure floatation process, Toshiba's waste water treatment system uses a UASB methane fermentation reactor tank to decompose organic matter in waste water and treats further the water through nitrification, denitrification, and membrane separation processes. The biogas that is produced as a by-product of the methane fermentation process is converted into steam by a boiler for use in starch production. Toshiba's waste water treatment system using UASB largely reduces the costs of chemicals necessary for the UASB treatment processes compared with conventional and commonly-used UASB systems (based on our investigation in 2013), because it does not use pH regulators in the methane fermentation reactor tank and requires less desulfurization agent for biogas due to the use of a biological desulfurization system.

Highlights

  • Because biogas is recovered in the gaseous phase section, the top of the gas-solid separator (GSS) is open to the gaseous phase section and the biogas outlet is free from blockages caused by scum (film-like floating residues on the water surface) and granules.
  • A submerged weir is installed before the overflow weir to make the granules lifted by biogas collide with the submerged weir, reduce the flow speed and let them quickly precipitate and not to cause their overflow.

Configuration Example

Configuration Example image

Configuration Example image

High-concentration Organic Waste water Treatment System

Overview

High-concentration Organic Waste water Treatment System image

Toshiba adopts UASB for high-concentration organic waste water treatment systems.
High-concentration organic waste water treatment systems treat waste water to an environmental sound level and then discharge the treated water.
The UASB methane fermentation bioreactor system provides excellent features such as high economic efficiency, enhanced energy efficiency, and ease of operation and maintenance (based on our investigation in 2013).
This system is suitable for treating waste water with a high amount of organic matter (BOD* concentration of 2,000 mg/L or more) such as waste water from food factories.

* Biochemical oxygen demand (BOD) is the amount of dissolved oxygen needed by aquatic microorganisms in water to decompose and stabilize organic matter. It is widely used as an indicator of the degree of organic pollution of water.

Features

UASB Methane Fermentation Bioreactor

  • Low electricity consumption
    No power supply is necessary for aeration.
  • Small amount of excess sludge
    Approximately 1/5th to 1/10th of that of the aerobic treatment method
  • Energy recovery
    The generated biogas can be used for electricity generation and as a heat source.
  • Small installation space
    Physically small because this system can provide a higher workload than aerobic treatment systems.
  • Easy operation and shutdown
    Seasonal and batch operations are possible.
  • No aeration system for aerobic treatment is necessary when methane fermentation treatment alone can satisfy the water discharge standard for a sewer.
  • Produces a smaller amount of excess sludge from the methane fermentation treatment process and can largely reduce the sludge disposal cost compared with conventional aerobic treatment systems.
  • Reduces the installation space requirement due to a high-load design.

Optional system; Toshiba's Two-stage UASB System

The following is the futures of our Two-stage UASB System, in addition to the above noted common features of UASB systems.

  • Toshiba's two-stage configuration delivers an even higher BOD removal rate compared with a single-stage system (based on our investigation in 2013).
  • Reduces sewerage cost, compared with a method in which discharge water is diluted in single-stage methane fermentation treatment according to our own simulation in 2013).

Application Examples

Basic system

Toshiba considers a system suited for particular raw water qualities to meet waste water discharge standards and selects either a basic or two-stage system.

Application Examples images

Two-stage methane fermentation treatment system

A two-stage system is used to further reduce the concentration of organic matter in treated water to a level lower than that achievable with the basic system.

Application Examples images

BOD removal rate = 96%

In areas where the BOD* standard for water discharge into a sewer is 600 mg/L or less, this system can treat waste water with an organic matter concentration as high as 15,000 mg/L*2 of BOD*.

*2 The actual value may differ depending on waste water quality or other external factors.

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Toshiba globally conducts business by leveraging its expertise and rich experience in the construction of water supply and sewerage infrastructure in Japan. We operate worldwide, offering end to end and customized solutions to meet our customers' needs. We are committed to assisting in the establishment of sustainable water circulation systems and the realization of advanced environmentally sound communities using our expertise and affiliates.

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