Assessing the performance of an anaerobic baffled reactor and a constructed wetland with different media in greywater treatment
Kigonya, Arnold C
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Wastewater has been mainly split into two main categories; black water and greywater. Greywater is the most abundant form of wastewater; it has far reaching effects on the environment through pollution. However, if managed well can be a resource with so many applications since its reuse can promote efficient and sustainable use of the limited water resources. A treatment system was set up at Africa Hall in Makerere University to treat greywater discharged from kitchen. The system consisted of an anaerobic baffled reactor (ABR) pre-treatment system and a constructed wetland secondary treatment. The constructed wetland consists of different filter media horse tail reed floating mat, plastic and pumice. Greywater from the kitchen was characterised to establish the quality and it was observed not to be safe for disposal. The systems were monitored for treatment efficiency across different parameters for a period of 8 weeks March to December. Samples were collected for laboratory analysis from the five collection points to assess the quality of water being discharged and the performance of the system. Flows were measured to establish the hydraulic load on the system and plant girths for macrophytes were also taken. The ABR achieved removal efficiency of 96.37 ± 469.56% for TSS, 34.93 ±2.94% for TP,34.91 ±31.45% for TN, 97.29 ± 588.57% COD and 93.21 ±551.82% for BOD5. The different media in the constructed wetland achieved removal efficiencies of 82.70 ± 18.70% BOD5 removal for the horsetail reed floating mat, 78.25 ± 10.25% BOD5 removal for plastic and 82.86 ± 47.73% BOD5 removal for pumice. For COD removal, the horsetail reed floating mat achieved 41.21 ± 3.12%, 5.77 ± 3.87% for plastic and 49.99 ± 9.72% for pumice. For suspended solids, the horsetail reed floating mat achieved a removal efficiency of 92.34 ± 3.52%, plastic achieved -12.53 ± 3.67% while pumice achieved -45.52± 19.47%. Overall, the findings also highlighted that pumice achieved the highest removal efficiency for the various pollutant parameters. The treated greywater was also observed to meet some reuse criteria for different applications such as irrigation and toilet flushing. There is therefore need to consider greywater treatment as a measure of reducing greywater environmental pollution by wastewater. The pumice media can be an efficient treatment media in the constructed wetland system and achieve proper treatment.