Q) I have a percolation pit made up of 5 cement rings. I use this percolation pit to hold filtered water from septic tank.
A) Personally... I would FIX the septic system so you do not need to do these things and I would REMOVE that cesspit as it is almost certainly a health hazard as you have described it.
Secondly, I don't know what you mean by "filtered" water - because unless you have a real filter (plastic is best in this environment) in the outflow pipe coming from the effluent baffle of your system, nothing is being "filtered" as it moves from the septic tank to your holding pit. Also, the ONLY purpose of that filter, if it exists, is to prevent solids from moving into a drain field or d-box - as solids building up at either stage of the system would eventually create a catastrophic failure of the entire system. If you are not regularly CLEANING THIS FILTER (at least once every 6 months to 1 year) you do not have one, or it is not being maintained correctly!
Q) I would like to drop chlorine tablet ( 1.67gm Water Purification Tablets, Each Tablet for 500 litres ) once in 10 days which is recommended.
A) See previous answer to the first question.
I also don't know where that "recommendation" comes from. For onsite wastewater treatment, an EPA Approved wastewater treatment tablet and a feeder would be required to ensure that there is a tablet (the proper type) in the effluent at every opportunity releasing the hypochlorite into the system. The effluent layer rises and falls with as the waste enters the system and flows out of the septic tank. The same would be true for your cesspit.
It just hit me that you are calling these chlorine tabs "water purification tablets"... DO NOT place drinking water purification tablets into this cesspit!!! Someone will eventually DIE because you THINK the pit is being "sanitized" when it is not. This is NOT hyperbolic - it is FACT!
Q) But I just wonder whether the chlorine in the water can corrode the ring well ?
A) Short answer is YES. The time this takes, and severity, can vary widely as it really depends on the level of corrosive gases generated by the hypochlorite and how much of the concrete is exposed to these gases.
For eg , I'm reading a post which says chlorine will increase the acidity in water and also chlorine has the ability to corrode the concrete
I am quite confused with the information available online.
at the same time I'm reading one more article saying that , the chlorine will disappear in 5 minutes by dissolving in water and the effect of chlorine will disaapear by max in 10 days so no impact on anything .. I hope this covers concrete as well.
Can someone clear the confusion here ?
First off - DO NOT USE pool chlorine - in ANY form!!! Pool chlorine tablets are made from trichlorisocyanuric acid and dissolve more slowly than calcium hypochlorite. There is a danger of explosion using swimming pool tablets since the tablets will release an explosive gas called nitrogen chloride as they may not be entirely submersed at all times. (Also DO NOT use potable water purification tablets - they're typically made from sodium dichloroisocyanurate [NaDCC] - which will destroy the good microbes in your tank that are necessary for proper aerobic decomposition.)
The ONLY chlorine tablets approved for use in wastewater treatment systems in the U.S. is calcium hypochlorite tablets. Regardless of what you are told, you should ONLY EVER use chemicals that are EPA-certified to treat WASTEWATER.
I'm sure there are other brands, (pro-chlor I think is one) but the only one I am familiar with is Accu-Tab and if you MUST use a treatment tablet - I would encourage you to look there - first! These chemicals are highly regulated in the United States because of their explosive potential so your ability to acquire them may be limited. (Try septic direct for online sales.)
Accu-Tab Aerobic Onsite Wastewater Treatment Brochure
Anyway, again, you are asking questions without revealing your state/country or even region. You obviously have a serious onsite wastewater problem that you are trying to address without the necessary knowledge, which is extremely dangerous given the pathogenic disease opportunities that are being created on your property. You also cannot expect folks to give you advice about a subject such as this without some indication of where you are geographically located. Different regions have intrinsic issues with wastewater treatment at this level that are specific to the geography - such as water tables, restrictive layers, soil composition, etc. The regulations controlling what you can and cannot do vary widely from region to region because of these differences.
The above information is based on an assumption that you are located in the United States and the chemical suggested (since you are talking chlorine generically) is legally available for your locale for the purpose you have stated. The absolute BEST advice anyone can receive regarding onsite wastewater treatment systems is don't waste your money on additives, just use and maintain your system properly. Maintaining your system properly will require you to have regular contact with a septic system professional. Current onsite wastewater system designs are unable to create a maintenance free wastewater treatment system for use on private land. This maintenance varies with the design required for your property and at the absolute minimum requires sludge removal every 1 to 3 years (depending on the size and usage of the system).
As I stated in my other response to your cesspit post - this situation is beyond your capability to address without the direct assistance of an onsite wastewater professional. I would strongly encourage you to engage such a professional to address questions specific to your installation.
Improperly modifying the treating of wastewater in your system is dangerous as it elevates the risk of pathogen related disease or illness - which IS REAL and it can be FATAL!