Performance improvements and water re-use at industrial wastewater treatment facilities

Performance improvements and water re-use at industrial wastewater treatment facilities
ENTRY DATE: 12 November 2013| LAST UPDATE: 12 November 2013
Categories: Water Resources | Wastewater treatment
Technological Maturity: At the demonstration testing stage
Technology Owners:

Toyo Engineering Corporation

Needs Addressed

The need to reduce the impacts of deteriorating quality of public waters (particularly enclosed water bodies, etc.) as a result of climate change, in areas that may face declining sanitation conditions. Particularly applicable in response to the need to mitigate impacts in regions where water pollution is occurring due to urban population growth associated with economic growth, or due to rapid industrial development. 

Adaptation Effects
  • Limiting the deterioration of water quality in enclosed water bodies due to the effects of climate change, etc.
  • Prevention of deterioration of sanitary conditions and reduction of disease due to climate change
  • Improved wastewater treatment capacity to deal with extreme events
  • Securing water resources to deal with drought resulting from climate change
Overview and Features

At oil refineries and petrochemical plants, the following technologies are introduced with the aims of improving the performance of on-site wastewater treatment facilities, controlling the volume of and recycling wastewater on-site, and preventing water/environmental pollution caused by high-salinity reverse-osmosis concentrate.

  1. Use wastewater recycling to control the quantity of water consumption
    • Change the existing flow of water treatment and water reuse
    • Increase the concentration of recirculating cooling water (water quality management through the use of scale inhibitors, etc.)
  2. Controlling the volume of wastewater and recycling wastewater by installing treatment facilities
    • Lime softener hardness removal equipment
    • Reverse osmosis (RO) equipment
    • Zero liquid discharge (ZLD) equipment

An integrated improvement plan for water treatment facilities is presented below.

Integrated improvement plan for industrial-use water and wastewater treatment

Topic

Current status

Improvements

Benefits

(1) Flow meters

Flow meters are not installed where required, making it difficult to correctly ascertain water balance

Install flow meters in required locations

Able to accurately ascertain overall water balance

(2) Bearing cooling water, etc.

After use, discharged into storm ditch

Reclaim and use as water supplied to cooling tower (promoting reuse)

Reduced water intake, reduced wastewater

(3) Cooling water blowdown)

Discharged untreated into storm ditch

Supply to existing reverse osmosis and ion exchange towers (promoting reuse)

Reduced water intake, reduced wastewater

(4) Treated wastewater

Water supplied to reverse-osmosis pure water equipment

Use to augment supply of water to cooling tower

Promotion of effective use of wastewater

(5) Concentration ratio of circulating cooling water

About 4.0 to 4.3 times

Increase concentration ratio by injecting scale inhibitors => Reduce recharge water and blowdown

Reduced water intake, reduced wastewater

(6) Discharge to greenbelt (forest)

Cooling water blowdown, use of treated wastewater

Significant reduction due to cooling water blowdown and reuse of treated wastewater

Reduced water intake, reduced wastewater

(7) High salinity wastewater (reverse osmosis concentrate, ion exchange tower recycled wastewater, etc.)

Discharged into storm ditch =>to greenbelt (forest)

Reclaim low-salinity wastewater, and eliminate liquid discharge (ZLD) by evaporation to solidify high-salinity wastewater

< Equipment components for zero liquid discharge>

-Water softening apparatus and installations

-Reverse osmosis -membrane equipment

-Evaporator

-Crystallizer

Reduced wastewater. Reduced discharge of high-salinity water => Environmental protection of forests

Source: Model project for improvement of the Asian water environment, 2012  (The synthetic improvement of the India industrial effluenttreatment institution, and a reuse promotion enterprise), Administrative Report.

Cost

Initial cost: 45.6 million US dollars
Operating costs: 3.8 million US dollars per year

Energy Source

Electricity

Ease of Maintenance
  • Routine maintenance is required for any newly added treatment facilities
  • Routine cleaning with cleaning agents is required in order to prevent fouling of the reverse osmosis membrane.
  • Regular disposal of solid waste is required.
Technology Performance

The proposed improvements have resulted in the outcomes indicated in the table below in terms of the reduction of intake of canal water, and the reduction of volumes discharged into the greenbelt (forest). For oil refineries and petrochemical plants, the potential combined total reduction in water intake was 17% and reduction in discharge into the greenbelt (forest) was 44%.

Reductions in Water Intake and Wastewater Discharge

   

Water intake from canal

Discharge to forest

Oil refineries

Current status

3,509m3/h

874m3/h

After improvements

2,859m3/h

494m3/h

Difference

650m3/h

380m3/h

Reduction ratio

19%

43%

Petrochemical plants

Current status

3,800m3/h

232m3/h

After improvements

3,239m3/h

120m3/h

Difference

561m3/h

112m3/h

Reduction ratio

15%

48%

Total

Current status

7,309m3/h

1,106m3/h

After improvements

6,098m3/h

614m3/h

Difference

1,211m3/h

492m3/h

Reduction ratio

17%

44%

 Source: Model project for improvement of the Asian water environment, 2012
(The synthetic improvement of the India industrial effluenttreatment institution, and a reuse promotion enterprise), Administrative Report.

Considerations (technology transfer criteria, challenges, etc.)

The main technical challenges relating to the comprehensive improvement and are indicated below:

  • Bio-fouling of the reverse-osmosis membrane The concentration at the wastewater reverse-osmosis membrane, and concentration of organic and other substances in gray water make the system prone to bio-fouling of the membrane surface and pipe interiors.
  • Disposal destination of waste solid matter Solid waste matter discharged from the crystallizer, one component of the zero liquid discharge equipment, is likely to amount to several tons per day, so it is necessary to make a sound decision on where to dispose of it.
  • Alternative to the crystallizer Evaporation and solidification equipment is expensive because it uses high-grade materials such as titanium. While considering operational factors and solidification performance, it is necessary to move toward practical commercial applications for wastewater recycling by considering possible alternative types of equipment.
Co-benefits, Suitability for Developing Countries

Creation of employment for installation, operation and maintenance of the equipment.