Grass filtration in parallel with VFCW technology for community wastewater treatment through the king's initiative nature-by-nature process

The 15-year research is aimed to apply the Vertical Flow Constructed Wetland (VFCW) technology along with growing Star, Kallar, Coast couch grasses for community wastewater treatment as obtained from Phetchaburi municipal after anaerobic digesting inside the 18.5 km High-density Polyethylene (HDPE) pipe. The results found that pH value did not evidently show any change of influent to effluent among grass species but drastic change due to treatment efficiency in Biological Oxygen Demand (BOD), Total Kjeldahl Nitrogen (TKD), Total Phosphorus (TP), and Total Potassium (TK) due to supporting rapidly growing of Star, Kallar, and Coast couch grasses, and also some parts of organic forms to escape from the VFCW technical units as volatile gaseous chemicals; and precipitating down to the VFCW technical unit beds as sludge. The Star and Coast couch grasses showed higher potential in community wastewater treatment efficiency than Kallar grass but treating power were not different in wide ranges. Besides, the heavy metals (Pb, Cd, Hg as example) were contaminated in both treated wastewater and sludge (sediment). However, the influent and effluent as inflow and outflow of VFCW technical units found very low contamination but three grasses (Star, Kallar, and Coast couch) showed their eligibility in treating heavy metals, especially when their age at 45-day growth as the same findings of treating BOD, TKN, TP, and TK according to meet highest treatment efficiency at age of 45 days. In other words, the harvesting age at 45 days was not only reached the maximum treatment efficiency as well as maximum grass biomass but also kept away from heavy contamination.