Great care should therefore be employed when removing acid by draining thecasing. Once it is collected, it is important that the acid be neutralised toincrease the pH (and hence reduce its corrosiveness) but also to remove thelead dissolved in the acid.

The acid should be diluted with an excess of water to give a 5 to 10-folddilution. The liquid should then be neutralized by mixing with an equal volumeof agricultural lime, or other alkaline material containing calcium carbonate, orsodium hydroxide. Use ofhydrated lime has the advantage of lower cost per unit of neutralizing capacitywhen compared to sodium hydroxide.

Coral rock may be an alternative in many PICs, although use of calciumcarbonate or sodium hydroxide is preferred. The coral rock to be used shouldbe dead coral, preferably washed ashore which can be crushed finely andadded to the liquid requiring neutralization. If the ro ck is to be used, it shouldbe crushed into very small particles to increase the surface area so that the neutralization reaction can proceed as fast as possible. If large particles areadded to the acid it may take a lot longer for the same neutralization level tobe reached.

After the additive has been mixed with the acid, universal paper is to be usedto test the resulting pH of the liquid. (Universal paper can be purchasedcheaply from chemical companies, again contact details are included later).Once the liquid has reached a pH of 7.5 it has been neutralised and is safe todischarge to the environment. It is important to ensure that the pH is withinthe range of pH 7-8, as outside of this range there will be levels of lead stilldissolved into solution.

To remove the lead precipitates after neutralization, the solution must then befiltered. Soil can be used as an appropriate filter medium. A column of soilcontained in a metal container ie. 44 gallon metal drum with each endremoved, may be suitable for this purpose. The liquid once drained throughthis filter is ready for release to the environment.

The soil should be regularly replaced if large quantities of battery acid is beingfiltered. It is crucial that the soil must be encapsulated by mixing with wetconcrete and can then be disposed to landfill as general waste. If the soil isnot mixed with concrete, the lead will leach through the soil and becomemobile in landfill leachate in high concentrations.

Another way to treat acid is to process it by reacting it with sodium hydroxideto convert it to sodium sulfate, an odorless white powder used in laundrydetergent, glass and textile manufacturing. This process takes a material thatwould be discarded and turns it into a useful product.