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Masthead

UNITING THE VIBRANT WORLD OF WATER - TO PROVIDE A PROACTIVE PLATFORM FOR THE WATER INDUSTRY TO CONVERGE AND WORK TOGETHER IN ACHIEVING SOLUTIONS TO GLOBAL WATER PROBLEMS.

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C O N T E N T S

ZLD - Need Not Be a Cost Centre!..............22

The article discusses on how effluent treatment plant can be converted to profit centre from cost centre. Read On..

By Dr. Harshvardhan Modak

Developing A ZLD System by Resource Recovery...........26

The article discusses various aspects of ZLD by resource recovery/management and examines the present scenario in

context of planning ZLD. Find out…By Dinkar Saxena

The Feasibility of Implementing ZLD................32

The ZLD is not easy task, but it is highly technical and complicated. A dedicated study is required for

characterization of an effluent. Read on…By Dr. Nitin Nimkar & Dr. Nandkishor Trivikram Joshi

ZLD and Environment Protection.............46

The article discusses the ZLD process as an environment friendly practice and looks at the related issues, which needs

to be addressed to make ZLD a true and meaningful practice to protect

By Dr. Syed Naimathulla

Latest Developments in ZLD Solutions..............54The article is an attempt to get familiar with the ZLD system concept and understand the latest developments.By Ravindra Joshi & Supriya Deshpande

Zero Discharge for Profit..........62The article discusses of achieving Zero Discharge using Eco-Logical treatment. It can save input costs during treatment and generate resources with extra profit. Read on…By Dr Uday Bhawalkar

Treatment of High TDS Liquid Waste: Is Zero Liquid Discharge Feasible?...................66A zero liquid discharge treatment system for the disposal of saline industrial liquid waste was proposed and evaluated in this study. Microfiltration was selected as a pretreatment process after a qualitative assessment against‘conventional’ options. By Alexander Robertson

Masthead ....................................4

Water Wire.................................10

Launch Pad................................14

Event Zone.................................16

Product Zone.............................20

Editorial Calendar......................98

Subscription Form....................100

Classifieds...........................101

Ad.Index................................104

Editor’s Note.............................106

RE

GU

LA

RS

Membrane Bioreactor: The Future of Wastewater

Treatment........84By Rajesh Shenoy

Flow Meter Solves Tough Application Challenge for the

City of Cedar Rapids......88By Toshniwal Hyvac Pvt Ltd

Wastewater - Zero Liquid Discharge Is it practical? Who implements and How!........80

This article discusses the practicality of implementing Zero Liquid Discharge Procedures and these procedures

are implemented by whom and how.By Daniel L. Theobald

Wastewater Program......93By Nalco

Ultrasonic Technology Provides Cost-Effective Level Measurement..................95By Peter Ward

C O N T E N T S

Wastewater - Zero Liquid DischargeIs it practical? Who implements and How!

This article discusses the practicality of implementing Zero Liquid Discharge Procedures and these procedures are implemented by whom and how.

By Daniel L. Theobald

This is in continuation with our series of Back to Fundamentals on water and wastewater. This document is intended to discuss practicality of implementing Zero Liquid Discharge (ZLD) Procedures and these procedures are implemented

by whom and how. This generic presentation utilizes my extended number of years of experience recycling and reusingwastewater based on information below:

Presentation Details:

• Overview and Practicality of achieving ZLD Discharge

• Which industries are candidates for implementing ZLD

• How to implement and achieve ZLD

Overview and Practicality of Achieving ZLD Discharge:

An overview Zero liquid discharge (ZLD) technology includes pre-treatment and evaporation of the industrial effluent until the dissolved solids precipitate as crystals. These crystals are removed and dewatered. The water vapor from evaporation is condensed and returned to the process. Zero liquid discharge is a process that is beneficial to industrial and municipal organizations as well as the environment because after implementation it can save money and has no effluent, or discharge.

ZLD systems employ the most advanced wastewater treatment technologies to purify and recycle virtually all of the wastewater produced.

Also, zero liquid discharge technologies help plants meet discharge and water reuse requirements, enabling businesses to meet stringent cooling tower blowdown and flue gas desulfurization (FGD) discharge regulations, treat and recover valuable products from waste streams and better manage produced water.

A ZLD facility is an industrial plant without discharge of wastewaters. Target ZLD is normally reached by waste water strong recovery systems, separation by evaporation or boiling of water in evaporators, crystallizers and condensate recovery. ZLD plants produce

In this series of Back to Fundamentals

on water and wastewater, the article discusses the practicality of implementing Zero Liquid Discharge Procedures and

these procedures are implemented by

whom and how.

80 Water Today l November 2015

solid waste. Due to excessive initial capitalization requirements and adequate availability of water required for most industries in many locations on the globe, investing in implementation and operating ZLD technologies can be impractical. However, specific industries in certain locations canmanage regulatory pressures and meet water reuse goals with effective ZLD wastewater treatment technologies using some of the guidelines below.

Which Industries Are Candidates For Implementing ZLD:

Industries more suitable for implementing ZLD technologies may include the following:

Power Generation: The power generation industry is one of the greatest consumers of water worldwide, making water and wastewater treatment a vital topic which could lend to benefits implementing ZLD technologies.

Downstream Refining and Petrochemical: Both process water and wastewater are key factors in successful operations in the petrochemical industry including downstream refining. These industrial plants have demanding environmental management challenges and regulations.

Upstream Oil and Gas: In recent decades, the oil and gas industry has undergone significant changes. However, water and wastewater treatment for upstream oil and gas water has remained a key factor for successful operations.

Unconventional Gas: Managing unconventional oil and gas wastewater from shale gas wells is challenging and requires a variety of mobile and central facility solutions. The demands of field operations on equipment and personnel require a high level of continued dedication, experience, and engineering in which ZLD technologies are applicable.

Mining and Metals: Finding source water for some remote mining installations can be a challenge. More and more industries are prohibited from discharging any liquid waste originating from their facilities and required to meet evolving environmental regulations; implementing ZLD technologies are helpful.

Infrastructure: Leading municipalities around the world, benefit by using ZLD technologies to help them meet their unique requirements such as space limitations, purity of water, and more.

These technologies also the needs of municipal end users by extracting the maximum possible water from the wastewater and meeting the municipalities’ service requirements.

How To Implement And Achieve ZLD:

The need to meet wastewater treatment regulations and reduce water usage is driving many industrial facilities to implement zero liquid discharge, or ZLD systems, as a solution. ZLD systems can consists of a vertical tube following a film evaporator or brine concentrator, followed by a forced circulation crystallizer enabling you to be able to eliminate liquid waste streams from your plant and produce high purity water for reuse.

Feed wastewater is transferred from a wastewater pond or a wastewater tank. This pumps into a feed tank as the ZLD treatment facility. Here, in the feed tank the pH is adjusted for de-aeration or de-carbonation. The feed pump then transfers the wastewater through the heat exchanger, where the temperature is raised to near its boiling point creating heated brine. The heated brine is then pumped up to the deaerator.

In the deaerator, non-condensable gases such as carbon-dioxide and oxygen are removed from the brine. The de-aerated brine then flows into the brine evaporator sump. The brine from the de-aerator enters the sump and mixes with a large volume of brine. The brine is transferred from the sump to the flood box, located at the top of the evaporator heat transfer tubes, using the recirculating pump. The brine in the flood box is distributed to each of the heat transfer tubes. The liquid flows down the tubes, coating the inside wall as a thin film within each tube. As the liquid flows down the tube a portion of the brine evaporates and produces steam. Both the liquid brine and vapor are flowing in the same direction.

For the brine that reaches the sump as liquid, it re-combines with the brine already in the sump as well as the new feed brine coming into the sump from the deaerator. That mixed volume will then recirculate back to the top of the tube and shell.

Evaporated water vapor flows through the mesh pad mist eliminators. The mesh pad mist eliminators remove any brine droplets from the vapor. That vapor, exiting the mist eliminators, flows to the vapor compressor. The compressor increases the vapor pressure slightly. The compressed vapor flows to the shell side of the heat transfer tubes of the brine evaporator. The vapor

Water Today l November 2015 81

condenses on the outside of the vertical tubes. The condensed vapor flows down the outside of the heat transfer tubes and is recovered as distillate. The distillate flows to the distillate tank and then is pumped through the heat exchanger. The hot distillate is cooled to heat incoming feed water. The cooled distillate is available for reuse or recycle. Concentrated brine from the brine evaporator is sent to the brine crystallizer. The concentrated brine is routed to the shell and tube brine feeder. The concentrated brine is heated to above its boiling point in the brine feeder. The heated brine then enters the crystallizer vapor body. Upon entering the crystallizervapor body, the heated brine flashes. When the brine flashes, water evaporates from the brine as steam vapor. This concentrates the brine and crystals form in the circulating brine. The flash vapor and the vapor body flows through the mist eliminator to the vapor compressor. Vapor from the compressor is routed to the shell side of the shell and tube feeder, where it condenses and is recovered as condensate.

Recovered distillate is available for recycle and reuse. The crystallized solids are further processed by a filter press or a centrifuge to achieve zero liquid discharge and in some cases used as a valuable by-product.

So hopefully you are ready to Begin now to Implementing ZLD procedures. However; beforehand or in the process, feel free to reach out to me with your ZLD or any other Wastewater questions.

Daniel L. Theobald is “Wastewater Dan,” proprietor of Environmental Services. He is a professional wastewater and safety consultant/trainer with more than 24 years

of hands-on industry experience operating many variants of wastewater treatment processing units and is eager to share with others his knowledge about water conservation. Wastewater Dan can be reached at TheWastewaterWiz01@gmail.com or www.

82 Water Today l November 2015