# Preliminary Study on Greywater Treatment Using Nonwoven Textile Filters
## 2 Materials and Methods
The expected problem of filters start-up feeding with greywater was that due to the low biodegradability of greywater (compared with STE), some difficulty with attaining satisfactory final biomass occupancy and pollutant removal efficiency could appear. Determination of pollution indicators, defined as: dissolved organic and nutrient compounds--five-day biochemical oxygen demand (BOD\({}_{5}\)) and chemical oxygen demand (COD\({}_{\text{Cr}}\)) and total phosphorus (P\({}_{\text{tot}}\)) was performed for greywater filtered through paper filters (with a pore size 4-7 \(\upmu\)m) and--as particulate pollution indicator--total suspended solids (TSS). Determination of BOD\({}_{5}\) was performed by the respirometric method and COD--by the dichromate method (Merck spectrophotometer). The content of the total suspended solids was determined by the drying-weight method. The concentration of total phosphorus in the greywater was investigated by the colorimetric method by means of a spectroquant Nova 60 Photometer (Merck, Germany) with Spectroquant kit No. 114449. The values of these indicators were determined in accordance with the following standards: PN-ISO 6060: 2006 (COD) [33], PN-EN ISO 6878:2006 (P\({}_{\text{tot}}\)) [34] and PN-EN 872: 2007 (TSS) [35]. The greywater was semi-natural. The selection and proportions of ingredients used for the semi-natural greywater (simulating bath/shower outflow) preparation were based with the aim of achieving greywater properties that were comparable to Polish households. The proportions of greywater ingredients were arranged to obtain those that are typical for European (Polish) natural greywater: respectively 62% from shower, 31% from laundry, and 7% from wash basin. These proportions are comparable to those mentioned in the literature [36; 37]. In order to make 36 dm\({}^{3}\) of semi-natural greywater for the experiment, the following ingredients were used: 12 dm\({}^{3}\) of natural laundry greywater discharged from the washing machine after washing 3-5 kg of clothes (washing powder, Ariel, Procter and Gamble, Warsaw, Poland), 24 dm\({}^{3}\) of artificial greywater simulating bath/shower greywater, prepared using: g 3.6 g of shampoo (Head & Shoulders, Procter and Gamble, Warsaw, Poland), 5.7 g of shower gel (Colgate-Palmolive, Warsaw, Poland), 0.42 g of liquid soap (Serpol-Cosmetics Ltd., Poland), and 24 dm\({}^{3}\) of tap water. The semi-natural greywater for the experiment was collected and prepared every several days and stored in a fridge. The degradability of used greywater expressed as chemical oxygen demand to biochemical oxygen demand (COD\({}_{\text{Cr}}\)/BOD\({}_{5}\)) rate was 3.2 for set I and 2.8 for set II, respectively. However, the semi-natural greywater being dosed was the same, the inflowing into the filters of set I and set II pollutants concentrations were slightly different due to the different average retention times in the bioreactors. The average values of pollution indicators in the greywater flowing into the filters of set I were on average for the whole time of the experiment: \(227.8\pm 27.2\) mg O\({}_{2}\) dm\({}^{-3}\) (\(n=18\)) for COD\({}_{\text{Cr}}\), 70.6 \(\pm\) 5.1 mg O\({}_{2}\) dm\({}^{-3}\) (\(n=18\)) for BOD\({}_{5}\), 6.4 \(\pm\) 1.1 mg P\({}_{\text{tot}}\) dm\({}^{-3}\) (\(n=18\)) for P\({}_{\text{tot}}\), and 45.8 \(\pm\) 15.8 mg dm\({}^{-3}\) (\(n=6\)for total suspended solids (TSS). The average values of pollution indicators in greywater flowing into the filters of set II were on average for the whole time of the experiment: 153.1 \(\pm\) 9.5 mg O\({}_{2}\) dm\({}^{-3}\) (\(n\) = 7) for COD\({}_{\rm Cr}\), 49.2 \(\pm\) 4.6 mg O\({}_{2}\) dm\({}^{-3}\) (\(n\) = 6) for BOD\({}_{5}\), 4.2 \(\pm\) 0.4 mg P\({}_{\rm tot}\) dm\({}^{-3}\) (\(n\) = 7) for P\({}_{\rm tot}\), and 49.4 \(\pm\) 28.5 mg dm\({}^{-3}\) (\(n\) = 4) for total suspended solids (TSS). The pollution compositions of the semi-natural greywater in the study fluctuated in the range of real greywater [4; 6; 38].