Vermicompost as Biofiltration Media to Control Odor from Human Feces

Global Journal of Environmental Research 2 (1): 18-22, 8 ISSN 199-925X IDOSI Publications, 8 Vermicompost as Biofiltration Media to Control Odor from Human Feces 1 2 1 Kunwar D. Yadav, Vinod Tare and M. Mansoor Ahammed 1 Department of Civil Engineering, SV National Institute of Technology, Surat, Gujarat, India 2 Department of Civil Engineering, Indian Institute of Technology, Kanpur, UP, India Abstract: There are a number of options to control the odor during the degradation of organic wastes and biofiltration is one of them. Fresh vermicompost has a high surface area, adequate absorption capacity and high diversity and population of micro-organisms. Vermicompost helps in degradation process as well as in suppressing the odor. Study was organized in order to use the vermicompost as a biofilter media to suppress odor and optimize the thickness of vermicompost to remove/degrade the volatile fatty acids (VFA) emission. The 2.5 cm thick vermicompost layer in bedding and covering was found to be sufficient enough to eliminate the odor of system and reduce the Volatile Fatty Acids level from 161.55 to 39.61 mg/g within a period of 21 days. Key words: Odor Vermicompost Volatile fatty acids (VFA) Human feces INTRODUCTION [5], treatment of toluene vapours [6] and removal of butyric acid [7]. The odor is one of the major issues in safe disposal The vermicompost is much superior compared of human excreta. According to Sato et al. [1], volatile to compost in bulk density, porosity and particle fatty acids (VFA); acetic, propionic and butyric acids size. The fresh vermicompost also has a high surface are the main malodorous substances in the human area and a rich diversity of micro-organisms to waste (about 9%). The physical processes (dilution, biodegrade the VFA [8-1]. The main objective of physical adsorption, covering and masking), chemical the present study is to use the vermicompost as processes (Scrubbing, oxidation and incineration) biofiltration media and to find out the thickness of and biological processes (Biofiltration) have been used vermicompost layer that is sufficient to control odor in the past to treat the volatile organic compounds and to reduce the odor causing VFA level. In the and among those biofiltration is the most cost effective present study, it was hypothesized that different and efficient method for controlling the odor [2]. thickness of vermicompost on bedding and covering Biofiltration means passing of odor from biological would affect on the odor and VFA level and help in the media followed by biodegradation of captured organic degradation process. It was also hypothesized compounds. The odor components are transferred that within -3 days organic matter would partially from gas phase to liquid and solid phase of the particles stabilize and it will not create nuisance to the environment in the filter material [3]. Physical structure (porosity, if we provide sufficient amount of fresh microbial culture surface area and density), temperature, moisture content to the system. and diversity of micro-organism are all key factors which influence the efficiency of the biofiltration process. MATERIALS AND METHODS Researchers have studied several odor causing gases by using the compost as filtration media for biofiltration Vermicompost: Fresh and mature vermicompost was process. Compost was used as biofiltration media for collected from the stock culture bin. The vermicompost control of odor from ammonia gas [3], hydrogen was produced from cow dung by utilizing the earthworm sulfide removal [4], biodegradation of styrene laden waste species Eisenia fetida. Corresponding Author: Kunwar D. Yadav, Department of Civil Engineering, SV National Institute of Technology, Surat, Gujarat, India E-mail: kdjhansi@gmail.com 18

Global J. Environ. Res., 2 (1): 18-22, 8 Table 1: Physicochemical Characteristics of Fresh feces and Vermicompost S. No Parameter Fresh Feces Vermicompost 1 ph 5.5 7. 2 Moisture Content, % 78. 5. 3 Electrical Conductivity, mmho/cm 42.8 11.7 4 Carbon, % (dry weight) 43.5.5 5 Nitrogen, % (dry weight) 3.75 1.78 control that had 5. cm thick human feces.15 g (wet weight) samples were colleted every day by mixing feces layer after scrapping out the covering layer in A, B and C reactor and in rector D directly from feces layer. The samples were analyzed for VFA, ph and moisture content. The moisture in the covering layer was maintained by sprinkling of water to maintain the microbial activity. 3 mm Methods: The analysis of volatile fatty acids (VFA) was done by titration method as per [11] and ph was determined by digital ph meter (Model No: CL-51, Toshniwal, India). Layer 3 Layer 2 Layer 1 3 mm 45 mm Fig. 1: Schematic Representation of Reactors and Different Layer of Materials Feces: Fresh human feces were collected from a nonflush, drop and store type of toilet from a village near IIT Kanpur, named Mandhana. The toilet was designed to have separate seats for defecation and anal cleaning. Feces from 4 different houses of approximately 16- persons using the toilet were collected daily and thoroughly mixed before using it. Some chemical and physico-chemical characteristics of material are given in Table1. Four sets of reactors made of GI sheet were used as depicted by the schematic diagram shown in Fig. 1 and configuration details in Table 2. It was operated for 21 days and 4.5 kg of fresh feces ( wet weight) were fed in all the reactors. The first and second reactors were covered with 2.5 cm and 5. cm thick vermicompost layers respectively, having moisture content of 5%. In third reactor, 2.5 cm thick bedding and covering of vermicompost was provided. The fourth reactor served as RESULTS AND DISCUSSION The VFA level in the fresh feces varied from 161.55 to 162.21 mg/g and ph 5.8 to 1. VFA level started decreasing from second day of experiment till the end of the experiment i.e. 21 days (Fig. 2). Substantial reduction in VFA level from 162.21 to 6.54 mg/g of feces in reactor-a was observed as compared to 162.21 to 92 mg/g (Fig. 2) in reactor-b with application of a thick (5. cm) double vermicompost layer. It was found that the efficiency of VFA reduction in reactor-a was low as compared to that of reactor-c (VFA decreased from 161.55 to 39.61 mg/g of feces), where the feces were actually situated between the two layers of the vermicompost. Therefore, it can be inferred that the application of vermicompost bed enhanced the loss of VFA from the system. All reactors showed in greater removal ranging from 4.7 to 75.49% in VFA as compared to the control bin i.e. reactor-d (feces only), which points towards the fact that vermicompost significantly enhances the decrease of VFA from feces during the processing. Vermicompost helps by increasing the ph and in the degradation of volatile fatty acids by absorbing and degrading the malodorous volatile organic compounds which are generated from human feces and reduces the odor. Table 2: Configuration Details of Reactors and Materials (Vermicompost, Feces) Filled in the Different Layer with Variable Thicknesses Layer 1 Layer 2 Layer 3 ----------------------------------------------------- -------------------------------------------------------- ------------------------------------------------ Reactors Material Thickness (cm) Material Thickness (cm) Material Thickness (cm) A Feces 5. Vermicompost 2.5 - - B Feces 5. Vermicompost 5. - - C Vermicompost 2.5 Feces 5. Vermicompost 2.5 D Feces 5. - - - - 19

Global J. Environ. Res., 2 (1): 18-22, 8 16 14 1 1 8 6 4 16 14 1 1 8 6 4 16 14 1 1 8 6 4 16 14 1 1 8 6 4 Reactor A: Feces with 2.5 cm vermicompost covering Reactor B: Feces with 5. cm vermicompost covering Reactor C: Feces with 2.5 cm vermicompost bedding and covering Reactor D: Feces only 1 2 3 4 5 6 7 8 9 1 11 12 13 14 15 16 17 18 19 21 6. 6. 6. 6. VFA (Volatile Fatty Acids) Duration, days ph Fig. 2: Temporal Variation in VFA and ph with or without Vermicompost Layer

Global J. Environ. Res., 2 (1): 18-22, 8 Table 3: Qualitative Measurement of Odor in all Reactors by a Group of Students Reactor A Reactor B Reactor C Reactor D -------------------------------- -------------------------------- --------------------------------- ---------------------------------- Days System Feces System Feces System Feces System Feces 1-2 - 3-4 - - 5 - - - 6 - - - 7 - - - 8 - - - 9 - - - 1 - - - 11 - - - 12 - - - 13 - - - 14 - - - 15 - - - 16 - - - 17 - - - 18 - - - 19 - - - - - - - - 21 - - - - Odor Level: - Nil, Mild, Moderate, High, Offensive The reduction in the odor and volatile fatty acid odor. The reactor-b system has a no odor in the emission was due to vermicompost characteristics system from first day (Table 3). Odor level in the feces (high population and diversity of microbial organisms, layer was depending on the degradation in the organics. high surface area and good bulking agent) as compared to The reactor-d has an offensive odor for the first one the control reactor. week and after that high odor up to end of the experiment The ph increased from 1 to 1, 1 to 7 and and it was due to absence of vermicompost layer. 5.15 to 7.34 in reactors-a, B and C respectively (Fig. 2). It indicates that the thickness of vermicompost layer CONCLUSION inversely affects the increase of ph and addition of vermicompost bed enhances the ph to normal or neutral Vermicompost cover with a thickness of 2.5 cm seems level. In control reactor, the ph increment was 1.35 to be the optimum configuration for a significant (i.e. 5.8 to 3) which is comparatively lower compared reduction of odor and use as biofiltration media. to ph increment in other reactors (1.6, 1.66 and 2.19 for Application of fresh vermicompost as bedding and reactor A, B and C respectively) using vermicompost covering (Sandwich model) seems as an attractive method layer. Vissar and Postma, [12]; Kay, [13]; suggested that to reduce odor and volatile fatty acids concentration and microbial oxidation of VFA could cause the increase in to maintain the ph. ph of the medium and vermicompost will increase the microbial activity in the waste. This further strengthens REFERENCES our observation that vermicompost has played a significant role in raising the ph. 1. Sato, H., T. Hirose, T. Kimura, Y. Moriyama and The qualitative analysis of odor was also done for Nakashima, Y, 1. Analysis of malodorous volatile all reactors every day in a reactor as a system and in the substances of human waste: Feces and Urine. feces layer (Table 3). The reactor A and C have a mild Journal of Health Science, 47(5): 483-49. odor up to 4 days in the system. Initially, for 3-4 days 2. Schlegelmilch, M., J. Streese and R. Stegmann, 5. volatile acids production was high and so a few cracks Odour managment and treatment technologies: An were developed in the covering layer and create the mild overview. Waste Management, 25: 928-939. 21

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