Battery washing is a vital step in proper forklift battery maintenance, improving performance and extending unit life. However the water cannot simply be dumped down the drain. In most cases, the same water is recycled to wash the next set of batteries rather than being disposed of. First a series of industrial wastewater treatment steps are necessary to clean up the water for reuse.

Filtration

Wash water picks up all kinds of contaminants and not just those that come from the batteries. It is necessary to filter out the particulates such as dirt or rust out of the water. This not only keeps the water cleaner for the next wash cycle but also protects equipment used in later stages of the industrial wastewater treatment process.

Other contaminants are too small to be picked up by the coarse filters used in the first step so another method is carbon filtering. An activated carbon filter carries a positive charge and this causes negatively charged contaminants to be drawn to and stick to the filter. Carbon filters are commonly used to remove chlorine or VOCs from the wastewater. These two filters together remove much of the ancillary contamination but don’t deal with the two most important impurities: acid and heavy metals.

Acid Neutralization

Over time the acid inside a battery tends to leak out, one of the main reasons they need to be washed. Before the wash water can be reused the acid needs to be neutralized. Failing to do so prevents the recycled water from being as effective in rinsing the next set of batteries. Acidic solutions are also conductive and acidic wash water could cause a battery to short out.

The acid neutralization step of industrial wastewater treatment typically involves another filter. This filter is made of an alkali metal such as calcium or magnesium. As the acidic water passes through the filter it dissolves a small amount of the alkali, neutralizing the acid. The neutralizer needs to be replaced periodically as it is used up.

Heavy Metal Extraction

Batteries need to use heavy metals such as lead or zinc in order to hold and release a charge. Battery acid tends to dissolve these metals. Every time the battery is washed a small amount of these metals is carried away in the wash water. Although the concentration of heavy metals is very low, one of the dangers of these elements is that it requires only a microscopic amount to do damage to the environment.

Heavy metals are extracted in industrial wastewater treatment by the use of filters different than the ones used in other steps. These are specialized filters designed specifically to remove heavy metal ions. Passing the wash water through these filters removes the dangerous metals so the water can be reused safely.

Once the water has passed through these industrial wastewater treatment stages it is clean enough to be used in the next washing cycle.