Effective wastewater treatment/recycling technologies for construction industry - A local experience

During the construction / demolition period of a site, various types of wastewater will be generated and discharged. These various types of wastewater are, but not limited to, water from bore piling operation, rain water and ground water collected, spray water for dust removal, truck cleaning water, sewage and kitchen wastewater, etc. In most of the construction sites, government foul sewers will not be connected to the site premises during the construction period, hence the wastewater will have to be discharged to storm water drain, inland and coastal waters, etc. In this regard, the quality of discharged effluent will be controlled to very stringent limits, such as suspended solids (SS) to 30mg/L, oil and grease (O&G) to 20mg/L, biochemical oxygen demands (BOD5) to 20mg/L, chemical oxygen demands (COD) to 80mg/L, etc. Without proper treatment, the discharged wastewater will exceed the discharge limits, resulting from not only polluting the environment, but also leading to heavy penalty to the construction companies. This paper will focus on presenting appropriate technologies to tackle different types of wastewater from construction sites. They are: 1. Effective chemical coagulation and sedimentation system for treating high solids content construction runoff / wastewater from construction activities; 2. Biological wastewater treatment system in continuous operation for treating organic waste bearing wastewater from site office toilets, etc; 3. Biological wastewater treatment system in batch operation for treating highly polluted organic waste bearing wastewater from kitchens and canteens; 4. Automatic wheels washing machine for cost effective management of truck wheels cleaning process.