Treatment of laundry greywater using different filter media and for reuse in hydroponics

Freshwater resources are depleting at an alarming rate. Treatment of laundry of greywater using various effective media filters and reusing the treated wastewater to cultivate lettuce in a hydroponic system creates an opportunity to mitigate water scarcity of food security. This study involved quantifying and characterizing laundry greywater from a washing machine produced by the selected household in Brgy. [village] Baligang, Camalig, Albay [Philippines]. Three different filters were designed, fabricated, and contained in PVC pipe. The first filter was a medium and coarse sand, and coco peat filter, which has a depth of 11, 15, and 10 cm respectively. The second filter was a coconut shell-activated carbon filter with a depth of 36 cm. The third filter was a multimedia filter with a combination of medium sand, coco peat, and coconut shell-activated carbon with depths the same as the first filter. For this study, a randomized block design was used with three different block times (6 a.m., 9 a.m., and 12:00 pm.) for running the wastewater through filters. After the filtration process, it was evaluated and reused the hydroponics setup (Deep Flow Technique) with fifteen treatments. Each treatment was supplemented with a nutrient solution to maximize plant growth. In terms of the removal efficiencies of BOD and total phosphorous, filter 1 got the highest percentage at 32.71% and 33.54%, respectively. Filter 3 got the highest total nutrigen and TSS of about 48.64% and 79.63%, respectively. Among the three filters, filter 1 got the highest values for the growth performance of lettuce for plant height (38.8 cm) and root length 34.1 cm). In terms of the leaf area, number of leaves, and plant weight, filter 2 got the highest values with 182.0 sq cm, 31.4 pcs, and 184.6 g, respectively. It can be concluded that the filter media composition had a significant role in the removal efficiencies and growth performance of lettuce. For the economic considerations, the return on investment per cycle was 16.26%, and the payback period was six growing cycles. Hence, this study contributes to the long-term sustainability of future resources.