DOI: 10.3303/CET2292099 Paper Received: 24 January 2022; Revised: 22 March 2022; Accepted: 30 April 2022 Please cite this article as: Esquivel Rafaele F.A., Castaneda-Olivera C.A., 2022, Efficiency of a Biofilter Based on Human Hair and Cariniana Decandra Sawdust for the Treatment of Laundry Water, Chemical Engineering Transactions, 92, 589-594 DOI:10.3303/CET2292099 CHEMICAL ENGINEERING TRANSACTIONS VOL. 92, 2022 A publication of The Italian Association of Chemical Engineering Online at www.cetjournal.it Guest Editors: Rubens Maciel Filho, Eliseo Ranzi, Leonardo Tognotti Copyright © 2022, AIDIC Servizi S.r.l. ISBN 978-88-95608-90-7; ISSN 2283-9216 Efficiency of a Biofilter Based on Human Hair and Cariniana decandra Sawdust for the Treatment of Laundry Water Franco A. Esquivel Rafaele, Carlos A. Castañeda-Olivera* Universidad César Vallejo, Campus Los Olivos, Lima, Perú caralcaso@gmail.com Nowadays, water pollution has become a problem that affects a large part of the population and the environment. The exponential increase of the population has generated that the laundry industries have a high demand, generating large amounts of wastewater. Thus, this research evaluated the efficiency of five biofilters composed of different proportions of human hair and Cariniana decandra sawdust in the reduction of physicochemical and microbiological parameters of laundry water. The biofilter components were physicochemically characterized to determine humidity, density, porosity, among others. The results showed that the biofilter composed only of hair at 2 hours of hydraulic retention had a higher treatment efficiency with reduction values of 75% in COD, 77.8% in BOD, 83% in phosphates, 77.3% in total nitrogen, 50% in sulfates, 91.1% in detergents, 68.6% in hardness, 29.4% in turbidity, 71.5% in electrical conductivity, 90% in total coliforms, 95% in thermotolerant coliforms and 91.5% in Escherichia coli. Finally, it is concluded that the Cariniana decandra hair and sawdust biofilters are friendly and efficient systems for treating laundry water. 1. Introduction Currently, water pollution has become a major problem affecting much of society and consequently the environment. This is due to the discharge of untreated wastewater into water bodies such as rivers, lakes, lagoons, sea and ocean (Noblet and Schweitzer, 2018). Exponential population growth has led to environmental degradation due to excessive consumption of water resources, generating emissions of higher volumes of effluents (Helm et al., 2021). In sub-Saharan Africa, more than 50% of the population lacks sanitation systems (UNICEF and WHO, 2019), and developing countries such as the United States emit 1.2 billion gallons of industrial wastewater annually (Riverkeeper, 2011). The high demand of the laundry industry has been generating higher volumes of effluents that cause environmental degradation (Mauchauffe et al., 2012). Residential laundry machines emit a total of 41 gallons of water per single use, while commercial laundry machines emit an average of 34.74 thousand gallons of wastewater (US National Park Service, 2021). Wastewater generated in laundries generally uses surfactants, enzymes and bleaching agents that remove stains and dirt (Hickey 2011). Laundry wastewater causes impacts on the environment due to the diversity of products (soap, detergents, carbonates, salts, and soda) used in the washing process (Patel et al. 2017). These waters go directly to sewage systems and end up in bodies of water, generally rivers, which are used as a source of irrigation for agricultural areas and recreational areas, thus generating problems for human health (Valenzuela and Campuzano, 2018). In Peru, 68% of wastewater is not treated before being discharged into water bodies, causing environmental degradation and, consequently, the spread of diseases is imminent. In the city of Cusco, Peru, water from laundries is discharged into the Huatanay River, presenting a high load of inorganic compounds, total suspended solids and detergent compounds (Vega and Regaño, 2020). Faced with this problem, many researches have been experimenting with the use of biofilters as systems for the removal of pollutants in water, which is generally composed of organic and inorganic material. These biofilters are systems that mimic wetlands by purifying water naturally (Yocum, 2014). Therefore, the present research aimed to evaluate the efficiency of biofilters composed of human hair and sawdust of Cariniana decandra for the treatment of laundry water. 589 2. Materials and methods 2.1 Obtaining and processing of human hair and sawdust from Cariniana decandra Human hair (10 kg) was obtained from hairdressers located in the city of Cusco in Peru. The hair was washed with distilled water to remove impurities and any particulate matter present. Subsequently, the human hair was dried outdoors for 2 days to eliminate moisture. On the other hand, Cariniana decandra sawdust (10 kg) was obtained from a timber mill located in the district of San Jerónimo in Cusco. The total amount of sawdust was sieved to eliminate dust and obtain a particle size of 3 cm. 2.2 Characterization of the filter beds The filter beds were physicochemically characterized to evaluate porosity, humidity, apparent density, actual density, volume and buoyancy. 2.3 Biofilter design The biofilter had the shape of a straight circular cylinder, with a diameter of 10.16 cm and a height of 40 cm. The biofiltration system is shown in Figure 1, and the percentage of components (beds) in each biofilter is shown in Table 1. Figure 1: Biofiltration system Table 1: Dosing of filter beds Dose Biofilter Human hair (%) Sawdust of Cariniana decandra (%) B1 25 75 B2 50 50 B3 75 25 B4 100 - B5 - 100 2.4 Laundry water treatment The treatment was carried out in 5 different biofilters subjected to 2 and 4 hours of hydraulic retention, according to the doses shown in Table 1. Samples were analyzed both before and after treatment, evaluating physical, chemical and microbiological parameters. The removal efficiency of each parameter studied was determined using equation 1. %𝐸𝐹𝐼 = (𝐶𝑖−𝐶𝑓) 𝐶𝑖 × 100% (1) 590 Where: % EFI, is the percentage of removal efficiency; Ci, is the initial concentration of the sample; Cf, is the final concentration of the sample. 3. Results and discussion 3.1 Characterization of the filter beds Table 2 shows the physicochemical characterization of the Cariniana decandra sawdust and human hair filter beds. Table 2: Characterization of the filter beds Parameter Porosity (%) Humidity (%) Apparent density (g/cm3) Actual density (g/cm3) Hydraulic holding capacity (%) Sawdust of Cariniana decandra 61.4 11 0.22 0.57 35.8 Parameter Density (g/cm3) Volume (cm3) Buoyancy (N) Humidity (%) Resistant to dry heat (°C) Resistant to humid heat (°C) Human hair 75 1200 3.1314 20 140 220 From Table 2 it can be observed that human hair has a higher density and humidity than Cariniana decandra sawdust. The density and humidity values for human hair are 75 g/cm3 and 20%, respectively. Whereas, Cariniana decandra sawdust has values of 0.57 g/cm3 and 11% for density and humidity, respectively. Filter beds allow the elimination of impurities present in the water, and these biofilters depend on the characteristics and properties of interaction with the substance or element to be retained. Cariniana decandra Sawdust was used due to its easy acquisition and low costs, and this is mainly composed of cellulose fibers linked with lignin (Quinaloa, 2017). Meanwhile, hair has keratin (α-keratin) as a component, which contains cysteine that has the capacity of alkaline organic solvent, Likewise, hair is a bioadsorbent that presents primary functional groups such as amino, carboxyl, hydroxyl and hydrogen sulfide that allow removing ions from wastewater (Gallegos 2021). 3.2 Laundry water treatment Table 2 shows the results of analysis of physical, chemical and microbiological parameters in the 5 biofilters subjected to 2 and 4 hours of hydraulic retention. It is observed that biofilter 4, which is composed of hair with 2 hours of hydraulic retention, has the best average efficiency (75%) of the physical, chemical and microbiological parameters compared to the rest of the biofilters used in the treatment. The other biofilters had average efficiencies between 64 and 73%, indicating good reduction efficiency of the studied parameters. The parameters with the highest percentages of reduction were microbiological parameters (Total coliforms, Thermotolerant coliforms and Escherichia coli) and detergents. In other research, Zhang et al. (2020) used a biofilter based on pine sawdust for wastewater treatment, achieving a 23.60% reduction in COD. Similarly, Manouchehri and Kargari (2017) used a cross-flow microfiltration system in the recovery of laundry water, achieving a 90.8% decrease in COD. On the other hand, Pulido (2018) used two biofilters of Eichhornia crassipes, Cyperus papyrus and Alocasia macrorrhiza for domestic wastewater treatment, having in both biofilters BOD reductions 91.23 and 91.55%.Hua et al. (2016) studied a wood chip bioreactor and recycled steel by-product filters for agricultural wastewater treatment. The woodchip bioreactor had an average phosphate removal efficiency of 17.4 - 56%. In the same way, Hu et al. (2021) used a fluidized bed of circulating pellets for the removal of hardness from graywater, achieving 80% removals. Similarly, Raketh et al. (2021) used rubber wood ash for sulfate removal in industrial wastewater, achieving reductions of 42%.On the other hand, Chambi (2018) employed the flocculation, coagulation and adsorption process for the treatment of laundry water using aluminum polychloride and aluminum sulfate, achieving detergent removal of 97.99% and 94.92%, respectively. Lopez (2018) decreased turbidity by 86% using Opuntia ficus cactus as a coagulating agent.Similarly, Salazar and Sisalema (2018) employed sawdust as a filtering agent for industrial wastewater treatment, achieving a 60% reduction in electrical conductivity. 591 Table 1: Removal of physical, chemical and microbiological parameters Biofilter B1 B2 B3 B4 B5 Hydraulic retention time Hours 2 4 2 4 2 4 2 4 2 4 P a ra m e te rs COD Ci 400 mg/L Cf 260 260 160 300 180 300 100 290 190 280 Removal (%) 35 35 60 25 55 25 75 27.5 52.5 30 BOD Ci 180 mg/L Cf 110 104 70 110 65 108 40 110 75 120 Removal (%) 38.9 42.2 61.1 38.9 63.9 40 77.8 38.9 58.3 33.3 Phosphates Ci 1.64 mg/L Cf 0.96 1.17 1.13 1.15 1.37 0.73 0.27 0.14 0.63 0.044 Removal (%) 41.5 28.7 31.1 29.9 16.5 55.5 83.5 91.5 61.6 97.3 Total nitrogen Ci 22 mg/L Cf 9 12 8 11 7 10 5 12 8 18 Removal (%) 59.1 45.5 63.6 50 68.2 54.5 77.3 45.5 63.6 18.2 Sulfates Ci 1200 mg/L Cf 310 300 304 360 305 510 600 680 550 570 Removal (%) 74.2 75 74.7 70 74.6 57.5 50 43.3 54.2 52.5 Detergents Ci 494 mg/L Cf 54.6 15.8 46.6 29 54 34 43.8 23.4 23.8 75 Removal (%) 88.9 96.8 90.6 94.1 89.1 93.1 91.1 95.3 95.2 84.8 Hardness Ci 3500 mg/L Cf 850 800 800 920 800 1100 1100 1100 1100 1200 Removal (%) 75.7 77.1 77.1 73.7 77.1 68.6 68.6 68.6 68.6 65.7 Turbidity Ci 545 NTU Cf 150 130 173 269 174 315 385 472 471 346 Removal (%) 72.5 76.1 68.3 50.6 68.1 42.2 29.4 13.4 13.6 36.5 Electrical conductivity Ci 8450 μS/cm Cf 1700 1560 1660 1830 1700 2040 2140 2380 2440 2230 Removal (%) 79.9 81.5 80.4 78.3 79.9 75.9 74.7 71.8 71.1 73.6 Total coliforms Ci 2400 UFC/100ml Cf 1100 150 460 150 460 460 240 460 210 75 Removal (%) 54.2 93.8 80.8 93.8 80.8 80.8 90 80.8 91.3 96.9 Thermotolerant coliforms Ci 2400 UFC/100ml Cf 460 150 210 75 210 150 120 150 75 75 Removal (%) 80.8 93.8 91.3 96.9 91.3 93.8 95 93.8 96.9 96.9 Escherichia coli Ci 1100 UFC/100ml Cf 120 39 28 15 75 93 93 20 75 75 Removal (%) 89.1 96.5 97.5 98.6 93.2 91.5 91.5 98.2 93.2 93.2 Average efficiency % 65.8 70.2 73 66.7 71.5 64.9 75.3 64 68.3 64.9 Ci: Initial concentration Cf: Final concentration 592 4. Conclusions Cariniana decandra sawdust and hair biofilters are efficient in the treatment of laundry water. Biofilter 4, which is composed only of hair with 2 hours of hydraulic retention, was the most efficient for the treatment of laundry water, achieving an average efficiency of 75.3% in the physical, chemical and microbiological parameters. After treatment with the biofilters, reductions of 75% in chemical oxygen demand, 77.8% in biological oxygen demand, 83.5% in phosphates, 77.3% in total nitrogen, 50% in sulfates, 91.1% in detergents, 68.6% in hardness, 29.4% in turbidity, 74.7% in electrical conductivity, 90% in total coliforms, 95% in thermotolerant coliforms and 91.5% in Escherichia. Acknowledgments The authors would like to thank "Investiga UCV" of the Universidad César Vallejo for financial support for the publication of this research. 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