Subject: STATUS OF WATER TREATMENT PLANTS IN INDIA

Subject: STATUS OF WATER TREATMENT PLANTS IN INDIA

Dear Sir ,

 Very good evening sharing imp points published by CPCB REGARDING STATUS OF WATER TREATMENT PLANTS IN INDIA. I HAVE GONE THROUGH IT IMP POINTS SHARING BELOW MAIN THING WHICH WILL BE HELPFUL TO AM GREEN TO DO BEST MONITORING IN INDIA.

CONTENTS

1. INTRODUCTION

2. Water QUALITY AND ITS CONSUMPTION

3. WATER TREATMENT TECHNOLOGIES

4. EFFECTS OF FLOURIDE & ARSENIC AND REMOVAL TECHNIQUES

5. OPERATION & MAINTENANCE OF WATER TREAT PLANTS

6. WATER QUALITY CONTROL AND ASSESSMENT

OPERATION & MAINTENANCE OF WATER TREATMENT PLANTS

Operation Problems

In most of the cases, although Water Treatment Plants are designed and got constructed by State Public Health Engineering Departments or concerned Water Supply and Sewerage Boards, their operation and maintenance is carried out by local Municipal Corporations. There is an emerging new trend to engage a private organization on contract for operation & maintenance of water treatment plants. In certain cases, it is carried out by Water Supply and Sewerage Boards or PHEDs. It is clear that no set pattern is followed in this regard.

Desirable operation and maintenance practices for important units are

discussed below:

Rapid Mix and Flocculation Facilities

Operational Problems

Operational problems associated with coagulation and flocculation processes typically relate to either equipment failure or process inefficiencies. Problems associated with equipment operations are specific to the installed equipment and are not discussed here. Problems associated with the coagulation process are typically indicated by high turbidity water in the sedimentation basin effluent and / or the filtered water. Some of the common causes for poor performance of coagulation and flocculation facilities are as follows:

• High effluent turbidity, with no floc carryover, can be the result of too little coagulant or of incomplete dispersion of the coagulant. Jar tests with varying coagulant dilutions and rapid-mix intensities should be performed and dose to be adjusted accordingly.

• Unsatisfactory effluent turbidity can also result from raw water that has low initial turbidity. An insufficient number of particle collisions during flocculation will inhibit floc growth. Increase flocculation intensity, recycling of sludge, or addition of bentonite provide a nucleus for floc

formation.

• High effluent turbidity with floc carryover is an indication of a poor settling of floc. High flocculation intensity will often shear floc and result in poor settling. Lowering the flocculation intensity, or add a coagulant aid will toughen the floc and make it more readily settleable.

• Too much coagulant will often result in restabilization of the colloids. If unsatisfactory performance is obtained, a series of jar tests with various coagulant dosages will help in determining appropriate dosage requirement. The feed rates should be adjusted accordingly.

• Calcium carbonate precipitate will often accumulate on lime feed pipes. Lime pipes should be flushed with an acid solution periodically, to dissolve the scale.

• Improper feed rate of coagulant through positive displacement metering pumps can be the result of siphoning through the pump. Pumps may be located in such a way that a positive head is present at all times on the pump discharge. An alternative correction method is to install a back-

pressure valve on the pump discharge.

Preventive Maintenances

The following preventive maintenance procedures are necessary for the satisfactory operation of rapid mix and flocculation facilities.

1. Performing jar tests on raw water samples daily when significant raw water quality changes are experienced. The coagulant dosages and mixer speeds should be adjusted accordingly.

2. Cleaning of accumulated precipitate and sludge from rapid mix and flocculation basins.

3. Every month calibration of chemical feeders.

4. Checking the chemical analysis of each delivery of coagulant.

5. Adjusting feed rates as indicated by the analysis and jar tests.

6. Lubricating the flocculator and mixer gear boxes and bearings as specified by the manufacturer.

7. Inspect rapid mix impellers and flocculator paddles annually. Removal of any accumulations of floc or calcium carbonate scale. More frequent inspections are required if build up is severe.

Sedimentation Facilities

Operational Problems

Operational problems associated with sedimentation basins typically relate toineffective sludge removal or short circuiting. Ineffective sludge removal commonly is associated with equipment problems or inadequate sludge removal practices. Short circuiting is typically the result of improper inlet or outlet design; it can also be the result of wave action, density currents or temperature currents. Common operational and maintenance problems and troubleshooting guides are as follows:

• Operational problems with sludge collection equipment may include the shear pins or motor overloads or both, generally due to improper sludge removal. Rapid checks include removal of sludge, ensuring proper shear pin installation, motor overload setting and also to remove debris in thebasin.

• Sludge withdrawal with low solids concentrations may result from an excessively rapid removal rate or improperly operated sludge collection mechanism. Checks include decreasing the removal rate and to ensure proper operation of sludge collection equipment.

• Clogged sludge withdrawal piping can be the result of insufficient sludge withdrawal, therefore, increases the removal rate.

• High effluent turbidity or floc carryover may result from an improper coagulation process. High turbidity or floc carryover may also result from short circuiting in the sedimentation basin. Possible corrective measures include inlet and outlet baffles. Tracer studies help in identifying short circuits.

• Algae build up on basin walls or weirs may create taste and odor problems. Regular cleaning of basin walls, maintaining a residualdisinfectant in the basin, restricting algae growth is required.

• Sludge with a high organic content may impart taste and odor problems to the finished water, therefore sludge removal rate may be increased.

Preventive Maintenances

The following preventive maintenance procedures are necessary for

satisfactory operation of the sedimentation facility:

o Cleaning of basins annually to remove any accumulated sludge and

algal growth

o Lubrication of the sludge collection equipment as recommended by the

manufacturer

o Testing the sludge collection overload devices annually.

o Testing the solids content in the sludge withdrawal line daily.

o Turbidity of effluent may be checked on a regular basis and whenever the water quality or flow rate changes.

Filtration Systems

Operational Problems

• Improper operation of filtration units can result in poor quality of finished water and damage to the filter bed. In order to ensure proper operation, operators must continually monitor the operation of the filter units. The filtered water turbidity and the head loss through each filter unit are of particular interest.

• The filters must be backwashed as soon as either the filtered water turbidity or the head loss through a filter unit reaches a preset maximum value. Also, if a filter unit has been idle for a period of time; it should be thoroughly backwashed prior to its being put back into service.

• Improper filter backwashing may cause inadequate filter cleaning and possible damage to the unit. If the back wash water is introduced too rapidly, the filter bed can be disturbed, or, in extreme cases, the filter bottom can be damaged. In order to reduce the chances of damage to

the filter beds from improper backwashing techniques, most filter systems utilize automatic backwash controls.

• The two most common problems encountered in filter operation are mudball formation and air binding. Mud ball formation is usually the effect of improper backwashing techniques, but improper media selection can also be the cause. Single medium filters historically show a greater tendency to form mud balls than do properly designed dual media and mixed media filters. Surface wash, sub-surface washing, or air scouring of filters before and during backwash also reduces the tendency to formmud balls in the filter bed.

• Once mud balls have formed in a filter bed, the most effective means of removing them is to remove the filter media and either replace it or thoroughly clean the media before placing them back into the bed. Once mud ball have begun to form in a filter bed, they will usually grow larger.

• Air binding of filter beds is usually caused by improper hydraulic design of the filter system. Possible solutions to air binding are (i) replacing the filter media with one with a different gradation, (ii) reducing the maximum flow rate through the filter and (iii) Inducing additional hydraulic head in

the filter effluent, to raise the hydraulic gradient in the filter bed Brief trouble shooting guide

Condition I: High head loss through a filter unit or filter run

Possible cases are:

1. Filter bed in need of backwashing

2. Air binding

3. Mud balls in the filter bed

4. Improper rate of flow controller operation

5. Clogged under drains

6. Improper media design: too small (or) too deep

7. Floc strength too strong – will not Penetrate media

Condition 2: High effluent turbidity

Possible cases are:

1. Filter bed in need of backwashing

2. Rate of flow too high

3. Improper rate of flow controller operation

4. Disturbed filter bed Mud balls in the filter bed

5. Air binding

6. Inappropriate media size or depth Low media depth (caused by loss during back wash)

7. Floc too small or too weak caused by improper chemical pretreatment.

Disinfection Facility

Routine maintenance should be scheduled to assure that problems are corrected before unnecessary damage occurs to the equipment. In this way, unplanned chemical and labour costs can be reduced, treatment efficiency maintained and many safety hazards prevented. Routine operation and maintenance of the chlorine feed systems includes the following.

• Inspection of the chlorinators, evaporators, and storage tanks each day to ensure proper operation. Low gas pressure or no feed may indicate flow restrictions, empty vessels, clogged injectors, or damaged equipment.

• Inspection of the diffusers. Diffusers may become plugged.

• Monitoring of the combined and total chlorine residual daily. Excess variations may indicate equipment malfunction.

• Monitoring of the treated water quality daily. Perform a periodic review of treated water quality. This should include analysis of daily reports.

• Draining of the contact chambers annually and repair of structures and equipment as needed.

• Testing of leak detectors and emergency equipment every six months and verifying of operator training in emergency procedures.

Management Information System and Indicators

The efficient and effective performance of an agency depends on a clear relationship between management activities such as planning, organization, selection and training of staff, coordination, direction and control of the functions of the agency. The interaction between the individuals at different management levels, together with use of information in the decision making process, is important to the agency’s performance. Each of the management levels has different centres of decision and each of these is supported by an information system.

Management Information System is defined as a formal system of making available to the management accurate, timely, sufficient, and relevant information to facilitate the decision making process to enable the organization to carry out the specific functions effectively and efficiently in tune with organization’s objectives. Originations have many information systems serving at different levels and functions within the organizations. The data fed into the management information system initially is internal data and later data from other institutions such as from community and others can also be fed. Each agency has to decide as to which information is relevant and then evolve itsown procedures for accurate collection, measurement, recording, storage and

retrieval of data. The management information system can be developed eitherby manual data collection or by use of software.

The result of actions by managers at the strategic, tactical and operational level is measured by Management / Performance Indicators. These Indicators represent a situation, an event or a change brought about by an action aimed at achieving a target set by an agency. These indicators allows the management to set targets, monitor the O&M, evaluate the performance of the agency and take necessary decisions and corrective actions.

WITH BEST REGARDS

Dr. Amar Nath Giri