Waste Wash-Water Recycling in Ready Mix Concrete Plants

Ayoup M Ghrair,Andrew Heath,Muath Al Kronz,Kevin Paine

doi:10.3390/environments7120108

Ayoup M Ghrair, Andrew Heath + Show 2 more

Open Access

https://doi.org/10.3390/environments7120108

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Abstract

The management of waste wash-water (WWW) is one of the most significant environmental problems associated with ready-mix concrete production worldwide. The problems are exacerbated should it be disposed of in an inappropriate manner. This study evaluated the potential of WWW recycling in ready mix concrete plants in Jordan. A representative waste wash-water sample (400 L) was collected from a basin in a ready-mix concrete company. A pilot plant on the lab scale was fabricated and installed. The treatment system consisted of a concrete washout reclaimer, wedgebed slurry settling pond, slow sand filtration unit, and a neutralization unit. Water samples were collected from all stages of the pilot plant and analyzed. The collected waste wash-water samples were utilized for replacement of well water (mixing water) at various ratios. Fourteen concrete mixtures were produced and cast, as well as tested at various curing ages (7, 28, and 90 days). The results show that the raw WWW was not acceptable as mixing water even after dilution as it led to significant reductions in concrete compressive strength and low workability. However, the WWW from the settling pond, the filtered WWW and the filtered-neutralized WWW at dilution ratios up to 75% were shown to be potential alternatives to fresh water for ready-mixed concrete. Therefore, the current guidelines for mixing water quality should be revised to encourage the reuse of the WWW.

Highlights

IntroductionJordan is one of the most arid countries in the Middle East and is facing severe water shortages
Introduction and Literature ReviewJordan is one of the most arid countries in the Middle East and is facing severe water shortages.The mean annual rainfall in more than 90% of the country is less than 200 mm
The results show that the raw waste wash-water (WWW) was caustic with pH value up to 12.6

Summary

Introduction

Jordan is one of the most arid countries in the Middle East and is facing severe water shortages. The mean annual rainfall in more than 90% of the country is less than 200 mm. The average rainfall in the mountain areas reaches up to 600 mm [1]. The current per capita water supply is 200 m3 /year for all purposes which is almost one-third of the global average. The problem of water scarcity is magnified by high population growth rates and influx of refugees from the surrounding countries.

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Results

Conclusion