OF JOURNAL CRITICAL REVIEWS ISSN- 2394-5125 VOL 7, ISSUE 14, 2020 PERFORMANCE EVALUATION OF VERMIFILTRATION TECHNOLOGY FOR THE TREATMENT OF WASTEWATER USING DETOXIFYING EARTHWORMS: A CASE STUDY Prof. S. K Singh1, Twinkle Bhatia2 1,2 Department of Environmental Engineering, Delhi Technological University, Delhi (110042), India Received: 14 March 2020 Revised and Accepted: 8 July 2020 ABSTRACT: Wastewater is defined as the contaminated sewage discharging from various sources such as residential, commercial, agricultural as well as industrial sites. It is produced by anthropogenic activities which is done at source through various processes. The wastewater from residences and organizations carries wastes such as urine and human feces, food waste and wastes coming from washing etc. are categorized as sanitary sewage or domestic sewage. The sewage containing liquid and solids coming from the domestic sites can be treated with the help of various conventional processes such as Trickling Filter, Activated Sludge Process, Rotating Biological Contractors, etc. However, each of the conventional process have some or the other disadvantages which slows down their efficiencies and thereby treated water is difficult to acquire from them. These disadvantages include more treating time, uneconomical, high operation and maintenance cost which may cause fly nuisance etc. Therefore, to treat such contaminated domestic wastewater, an economical, odor-free, eco-friendly with low operation and maintenance cost, technology is required. A novel technology called as Vermifiltration technology is one such eco-friendly technology which fulfills all the above criteria to treat the domestic sewage. This technology uses earthworms which act as a „biofilter‟. In a vermifilter, removal ratios for BOD5, TSS, COD, and Fecal coliforms is about 90%, 85%, 98% and 99% respectively. The paper majorly discusses about the Vermifiltration process, its performance evaluation through sampling and data analysis of treated sewage of educational institute, its advantages and disadvantages, its scope in future along with some research work done using this novel technology to treat the wastewater. KEYWORDS: domestic wastewater, Vermifiltration technology, treatment processes, water quality parameters I. INTRODUCTION Wastewater is any contaminated water which originates predominantly from Domestic, Commercial, and Industrial sites along with Surface water, Storm water as well as ground water. There are a number of treatment processes to remove the contamination and toxicity in wastewater. There are various sources of wastewater generation which includes residential, commercial, agricultural, and industrial sites. Toxic wastewater may cause health risks such as Cholera, Amoebiasis, Giardia (also known as beaver fever) etc. There are various technologies that have been used in past to treat the wastewater but it has been found that none of the conventional technologies have qualities like odor-free, sludge-free, eco-friendly or is economical with low operation and maintenance cost altogether. One of the novel technologies which is being used nowadays which tackles all such problems is the Vermifiltration technology. It is similar to trickling filter as it is also an attached growth system. Vermifiltration technology do not require any external energy, except for pumping and due to this, it can be useful for treating wastewater in small communities also. In this technology, there is no sludge formation which needs extra spending on landfill disposal. Also, it is an odor-free process and the treated water is clean enough to be used again in parks, gardens and even for farm irrigation. The major objectives of the study is: To evaluate the performance of Vermifiltration technology for the treatment of sewage through sampling & data analysis, to compare the pros and cons of the technology along with the research work done and to find the future scope of the novel Vermifiltration technology. II. VERMIFILTRATION TECHNOLOGY Vermifiltration was primarily coined by researchers of the University of Chile in the year 1992 as cost-effective, no sludge producing and sustainable technology. In the process filters known as a Vermifilter is a type of 2905 OF JOURNAL CRITICAL REVIEWS ISSN- 2394-5125 VOL 7, ISSUE 14, 2020 biofilter for the wastewater treatment. Vermifilters works in an aerobic environment and wet substrate which provides the growth of microorganism as a biofilm known as slime layer. Microorganisms such as bacteria takes part in the degradation of the organic matter biochemically which are present in wastewater. Earthworms synchronize microbial biomass and activity by feeding on micro-organisms. Organic matter and Biofilm which is consumed by the earthworms is then digested into the organic matter turns into humus which is called as a vermicompost. This vermicompost is rich in minerals and nutrients as the earthworms consume the organic matter into their gut and we get degraded humus. It can be applied to soil to enhance the fertility of soil and structure. Earthworms used in Vermifiltration technology Earthworms known as the farmers best friend are segmented and tubular worms. The earthworm‟s digestive system is all over the length of its body and it respires through its skin. Earthworms excavate underpasses in the soil which as a result provides aeration to the soil thereby making way for hydrogen, oxygen, and nutrients to reach deep down the soil. They liberate waste known as castings from their bodies after organic matter is digested. Castings have various nutrients that the plant consume for their growth and nourishment. In Vermifiltration technology, earthworms play the major part in treating the wastewater by degrading the organic matter from it. Earthworms can also consume toxic heavy metals to make the industrial wastewater. All the earthworm species are best suited under all climatic conditions. Niche diversification of earthworms used for Vermifiltration are as follows: S.no. Earthworm Moisture Weight of Temperature Active phase Existence of species content adult tolerance of of earthworms over earthworm earthworms earthworms the world (distribution) 1. Eisenia fetida 20 – 40% 0.3 – 0.7g 15 – 30oC Active Found in (Red worms) throughout temperate regions the year of Europe, India and North America 2. Eudrilus 20 – 40% 1.5 – 2.5g 18 – 35oC Active Found in South Eugeniae throughout America and (African night the year Tropical Africa crawler) 3. Perionyx 30 – 50% 0.8 – 1.2g 8 – 30 oC Active Exist in Tropical Excavatus throughout countries like (Indian blue the year India worm) 4. Drawida Barweli 40 – 50% 0.2 – 0.5g 20 – 30 oC Active in Found in Tropical months countries August to November 5. Lampito Mauritii 20 – 40% 0.8 – 1.5g 18 – 28 oC Active in Exist in Plains of months June Indian Peninsula to August Table 1: Detailed Description of Earthworm Species Figure 1. Red Tiger Worms Figure 2. African Night Crawler Worms Formation of Vermifilter bed 2906 OF JOURNAL CRITICAL REVIEWS ISSN- 2394-5125 VOL 7, ISSUE 14, 2020 Vermifilter is a cylindrical shaped biofilter having depth of 1-1.5 m and is divided into four parts in which at the bottom gravel of size 10-20 mm is placed, then another layer of gravel of size 2-4 mm is placed, sand of size 1-2 mm and garden soil bed for earthworm are placed in the vermifilter. A homogeneous mixture of Garden soil and Sawdust at a Volume Ratio of 3:1 is adopted usually to form the vermifilter bed. Natural ingredients such as wood chips, mud balls etc. can be used as filter media in place of garden soil or the mixture of the two can be taken can be in which earthworms resides. Vermifilters are naturally ventilated and is equipped with polypropylene perforated pipe to provide equal distribution of the wastewater and for aeration, a couple of pipes are inserted. The earthworms are given about a week of settling time in the soil bed so that they can acclimatize in the new environment. Figure 3. Vermifilter bed with wood chips Performance analysis of Vermifilter on the basis of water quality parameters The performance evaluation has been done on the basis of testing parameters of wastewater quality and the quality parameters of treated effluent coming from the STP (1MLD) in Delhi Technological University Campus, Rohini, Delhi (India) and the data have been taken from Noida testing Laboratories. Testing of these quality parameters decides whether the quality of water is up to mark for land irrigation or not. Various parameters have been listed along with the values of wastewater before and after treatment with Vermifiltration Technology. SAMPLING AND ANALYSIS DATA (Noida Testing Laboratories) Sample received on:07/01/2020 Sample description: Treated sewage from STP Project name: DTU Bio-filter STP, Bawana Road, New Delhi Sample Quantity/Packing detail: 1 lit/Plastic cane Analysis Duration:07/01/2020 to 13/01/2020 S.no. Parameters Test Method Results Unit Limit asper MoEF/CPCB Norms 1 pH IS:3025(Part 7.68 - 6.5-9.0 -11) 2 TSS IS:3025(Part 18.6 mg/l 100 (max) -17) 3 COD IS:3025(Part 39.0 mg/l 250 (max) -58) 4 BOD3 IS:3025(Part 9.0 mg/l 30 (max) -44) 5 Oil & grease IS:3025(Part <1.0 mg/l 10 (max) -39) 6 TDS IS:3025(Part 998 mg/l No limit specified -16) 2907 OF JOURNAL CRITICAL REVIEWS ISSN- 2394-5125 VOL 7, ISSUE 14, 2020 7 Faecal IS: 152 mg/l <1000 MPN/100ml coliform 1622:1981 (MPN/100ML ) Table 2. Wastewater Parameters Analysis Figure 4. Color variation in raw and treated sewage Pros and Cons of Vermifiltration technology PROS OF VERMIFILTRATION (1) Vermifiltration is a sludge free and odorless technology. (2) A smaller number of mechanical equipments are required. (3) It is an economically affordable technology with environmentally sustainable features. (4) The nutrients and filtered water are used for irrigating useful vegetation. (5) Wastewater is treated in few days as the conventional treatment processes may take up several days to treat the wastewater.