Heavy metal-contaminated soil from AC condensate reuse can be treated via electrokinetic remediation or phytoremediation for in situ cleanup, preserving soil structure. Soil washing is effective but requires excavation and generates secondary waste, so method choice depends on soil type, contaminant levels, and site specifics.

Zaher Salem

In recent years, the practice of reusing condensate water from air conditioning systems for irrigation has become common, especially in arid and hot regions such as the Middle East. While condensate water is often considered relatively clean, as it originates from the condensation of water vapor in the air, it can actually contain various pollutants, including heavy metals. These metals may come from two primary sources: polluted outdoor air (from industrial emissions or traffic) that passes through the air conditioner’s evaporator, and the internal metal components of the system itself (such as copper, aluminum, or galvanized pipes), which can corrode over time and release metals into the condensate. Long-term use of such water for irrigation can lead to the gradual accumulation of heavy metals in the soil, negatively affecting plant health, soil microbial activity, and potentially food safety if the land is used for agriculture. The current presence of dying plants in the area is a clear indication of advanced contamination.

In such cases, it is recommended to conduct thorough chemical analysis of both soil and water to identify the specific heavy metals present and their concentrations. Based on these results, appropriate remediation methods can be applied. Physicochemical methods include soil replacement, stabilization of metals using materials that bind them (such as zeolites or biochar), or soil washing with chemical solutions that remove contaminants. Biological methods, such as phytoremediation (using plants that absorb heavy metals) and bioremediation (using microorganisms that degrade or transform pollutants), offer more environmentally friendly and sustainable options. Additionally, it is advisable to filter condensate water before reuse and to consider alternative sources for irrigation. In all cases, a systematic and expert-led approach is essential, along with continuous monitoring of soil and water quality, to prevent further degradation of the ecosystem.

Dr. Zaher

The subject not easy to discuss on public, because lot of information should be delivered like the total area, the location either on Wadi or flat surface, topography, soil type, the nearest rock type if it sedimentary or volcanic, also the temperatures, rain fall......

But, for sure there are many new methods and additives can solve the problem and mainly from the surrounding environment, but first we should know the salinity sources I think it come not from water itself but it is result of washing the soil, the deionized water solving and dissolving the soil salts and minerals causing the salinity, so there are two ways first the design of irrigation and its type, second porosity of soil and some eco and natural materials should be added.

The salts not came from industrial pollution or air pollution, the source is inside the soil itself.

So, many details should be known and discussed then the solution will come easy.

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Wael

I agree with Wael Fathi Galal.

Condensate water from air conditioners is essentially distilled water — it is formed by the condensation of atmospheric humidity on cold surfaces. This water typically has the following characteristics:

• Very low levels of dissolved salts or metals,
• Extremely soft (low electrical conductivity),
• Slightly acidic (pH ~5–6), due to dissolved CO₂ from the air.

Consequences of Using AC Condensate Water for Irrigation

When such water is applied continuously to demineralized or weakly buffered soils, the following effects can occur:

1. Leaching Effect

• Since condensate contains no dissolved ions, it acts as "hungry" or aggressive water, seeking minerals from the surrounding environment.
• It can dissolve and mobilize naturally occurring heavy metals in the soil (e.g., Cu, Zn, Pb, Cd, Ni, As), especially in slightly acidic soils.

2. Acidification-Enhanced Solubility

• The slightly acidic pH of the condensate increases the solubility of heavy metals.
• As a result, these metals enter the soil solution more readily, where they can be:
  • taken up by plants (leading to phytotoxicity),
  • or leached further into the subsoil or groundwater.
• Consequences include plant damage, heavy metal accumulation, and soil degradation.

3. Disruption of Soil Structure and Cation Balance

• The continuous input of ion-free water can disturb the cation exchange balance, especially in calcareous-deficient soils.
• This may lead to soil acidification and increased availability of toxic elements such as aluminum (Al³⁺).

Underlying Soil Contamination as a Likely Source

It is highly probable that the heavy metal contamination was pre-existing in the soil and not introduced by the condensate itself. Possible sources include:

• Geogenic origins, such as mineral-rich parent materials.
• On the Arabian Peninsula, for example, peridotite rock formations are widespread — these are naturally rich in heavy metals such as nickel, chromium, and cobalt.

Thank you very much Peter Faber.