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WHY, NOT GETTING OUTLET RESULTS IN BIOLOGICAL AERATION SYSTEM IN EFFLUENT / SEWERAGE TREATMENT PLANTS?

By Environ

September 1, 2014

Aeration System is the HEART of any Biological ETP / STP & MAXIMUM ENERGY is consumed in Aeration System to reduce the BOD / COD & as this is a NON PRODUCTIVE PLANT the ENERGY used in such SYSTEMS is also a MONETARY WASTE for any INDUSTRY / CETP / STP. So to SAVE such Expenses the INDUSTRY – ETP / CETP / MUNICIPAL CORPORATIONS should enquire whether the Invested Capital will work efficiently for a long period of time WITH LOW MAINTAINANCE.

There are many Aeration Systems available in the market like Mechanical Aerators i.e. Slow Speed / High Speed / Aspirator/ Aerators with Draft Tube Arrangements / Energy Efficient Aerators etc, Diffused Aeration System having many types of Diffusers etc. Jet Aerators, ELO2 Aerators etc. etc. & all the manufacturers claims there systems are very efficient. Then why the INDUSTRY- ETP / CETP / STP are facing problems in getting the required results as per the Norms of PCB in there Aeration Systems even after burning the large amount of ENERGY? The reasons are:

The subject is NEW to the end users, so they are totally dependent on the Consultants / Experts. The plants are perfectly designed by Consultants / Experts. After designing they always recommend 2 – 3 known manufacturers of such Systems in there Tenders. The INDUSTRY / CETP / STP never take the references from the manufacturers of the Systems working efficiently in other plants. They take the project very lightly, but they always forget that this is our MORAL RESPONSIBILITY FIRST & STATUTORY requirement & if the system fails then they will be facing lot of troubles / problems in future, so the INDUSTRIES – ETP /CETP / STP – MUNICIPAL CORPORATIONS / CONSULTANTS / EXPERTS should be very serious before taking any decisions of installing such systems. Generally, such projects are offered on TURNKEY BASIS, in such cases the TURNKEY EXECUTORS always try to purchase the equipments at a low cost to increase their profits, but they are not aware that after finishing Civil, Piping, Electrical work THE FINAL RESULTS IS TO BE ACHIEVED ONLY BY MECHANICAL SYSTEMS. They should Provide the characteristics of the Effluent, design details like dimensions of Aeration tank etc & should ask questions to the manufacturers of such systems like: Calculations of HP of Aeration System i.e. How the HP of the Aeration System arrived? How the manufacturer is giving Guarantee. Does the manufacturer gives the Guarantee of achieving the final out put results OR he is giving the Guarantee only of Oxygen Transfer efficiency at Standard Conditions? He had considered the depth of the Aeration Tank? What steps he will be taking for Aeration tank having more depths than 2.5mtrs? Does the manufacturer had TESTED the manufactured Aeration System like OXYGEN TRANSFER & MIXING efficiency which is a MUST in any AERATION SYSTEM? If yes then WHERE? Is the manufacturer is capable to SHOW the OXYGEN TRANSFER TEST if required by the INDUSTRY / STP – MUNICIPAL CORPORATION/ CETP / EXPERT / CONSULTANT?

ENVIRON IS THE ONLY MANUFACTURER IN INDIA WHO HAVE GOT OXYGEN TRANSFER TESTING FACILITY FOR THE AERATORS UP TO 150 HP RATINGS & HAD TESTED THE OXYGEN TRANSFER ALONGWITH MIXING EFFICIENCY OF THE PROTO TYPE AERATOR BEFORE PLACING THE AERATOR IN THE MARKET.

At the initial Commissioning stage the manufacturer of Aeration System / Turnkey Executors show the handsome results but, after they hand over the plant to the End User say after a period of time of 6 – 10 months the efficiency of the OUT LET Parameters of the effluent getting disturbed (THIS IS DUE TO IN EFFICIENT AERATION SYSTEM) & the End User starts facing the problems of NOT GETTING RESULTS, & mean time the Guarantee of the equipments is over. None of the END USER who is facing problems in achieving the results WILL DISAGREE with this. What, if the results are not achieved after a period of time & investing a large amount of capital?

We are in this field since 1979 & we always try first to explain the facts (educate) to the client & then ask them to take their own decision, in such cases after understanding the Technical Features & their requirement the end users are always in a position to take RIGHT DECISIONS.

IN ANY MECHANICAL AERATION SYSTEM APART FROM OXYGEN TRANSFER MIXING EFFICIENCY IS EQUALLY IMPORTANT the Oxygen Transfer / Mixing Efficiency depends on the Design of the Aerator Impeller. Each & every Aerator Impeller has its own INFLUENCE ZONE & limitations to cater particular depth of say 2.5mtrs. but as per our experience, if the tank depth is more than 2.5mtrs., then there will be settlement at the floor level, which will create septic conditions & the D.O. level reduces & sometimes goes down to ZERO, which all the Aerator Manufacturers, ETP / STP Designers, Consultants, Environmental Engineers, Experts, Turnkey Executors etc. will agree.

Now a days, as due to the space constraint, most of the Aeration Tanks are designed with higher depths. As the depths of the Aeration Tank is more than 2.5mtrs. Environ believes that it is the MORAL DUTY of the Aerator Manufacturer to design the Aerator Impeller accordingly considering the depth of the Aeration Tank, but it is not possible without doing the experiments OR R&D. ( NONE OF THE MANUFACTURER IN INDIA EXCEPT ENVIRON IS CONSIDERING THE AERATION TANK DEPTH BEFORE MANUFACTURING )

As the INDUSTRIES – ETP / CETP / STP – MUNICIPAL CORPORATION might not be aware that mostly every manufacturer of the Mechanical Aerators have their standard Design of the Impellers for standard HP e.g. The design of 25 HP Impeller is standard i.e. The Aerator Impeller of 25 HP installed in the Aeration tank depth of 2.5mtrs, the same Standard Design Impeller is Supplied & Installed in 3mtrs / 3.5mtrs / 4mtrs / 4.5mtrs / 5mtrs. It is very simple to understand that every Impeller has its own limitations to offer the results up to particular depth (SIMPLE THEORY OF PUMP – SUCTION & DISCHARGE) How the same design of the Impeller will be efficient in 2.5mtrs – 5mtrs? The Impeller which works in 2.5mtrs.will never work in 3mtrs – 4.5mtrs OR 5mtrs.Depth & due to which SLUDGE IS SETTLED at the FLOOR LEVEL of Aeration Tank. (THE INDUSTRY – ETP / MUNICIPAL CORPORATION – STP / CETP WHO ARE NOT ACHIEVING THE RESULTS CAN CHECK IN THERE AERATION TANK THERE WILL BE MINIMUM (GUARANTEE OF ENVIRON) 1 MTR. / 1.5 MTRS. SLUDGE IS SETTLED. If the SLUDGE is settled in Aeration Tank it creates the septic conditions due to which the OXYGEN TRANSFER EFFICIENCY REDUCES & THE D.O LEVEL WILL BE ZERO, SO RUNNING THE AERATORS IN SUCH CASES IS A WASTE OF ENERGY & MONEY. So in particular cases NO BODY can blame to Consultants / Experts / Designers as the design is properly done. The failure is only due to the Performance / Design of the Aerator, as the MIXING EFFICIENCY of the Aerator Impeller is missing (DUE TO MORE THAN 2.5MTRS. DEPTH).This is one of the main & basic reason for not achieving the results in AERATION SYSTEMS & It also proves the efficiency of the Aerators.

ENVIRON ACCEPTS CHALLENGE TO REDUCE 20% TO 70% ENERGY IN EXSISTING AERATION SYSTEM HAVING THE AERATION TANK DEPTH UPTO 6 MTRS. SWD OFFERING THE GUARANTEED RESULTS AS PER THE NORMS.