A vermifilter (also vermi-digester or lumbrifilter) is an

aerobic treatment system An aerobic treatment system (ATS), often called an aerobic septic system, is a small scale sewage treatment system similar to a septic tank system, but which uses an aerobic process for digestion rather than just the anaerobic process used in sep ...

, consisting of a biological reactor containing media that filters

organic material Organic matter, organic material or natural organic matter is the large source of carbon-based compounds found within natural and engineered, terrestrial, and aquatic environments. It is matter composed of organic compounds that have come fro ...

from

wastewater Wastewater (or waste water) is water generated after the use of freshwater, raw water, drinking water or saline water in a variety of deliberate applications or processes. Another definition of wastewater is "Used water from any combination of do ...

. The media also provides a habitat for

aerobic Aerobic means "requiring air," in which "air" usually means oxygen. Aerobic may also refer to * Aerobic exercise, prolonged exercise of moderate intensity * Aerobics, a form of aerobic exercise * Aerobic respiration, the aerobic process of cellu ...

bacteria and composting earthworms that purify the wastewater by removing pathogens and

oxygen demand Oxygen demand is an environmental chemistry term that may refer to: *Biochemical oxygen demand (BOD), the amount of oxygen needed by organisms to break down organic material present in a water sample *Carbonaceous biochemical oxygen demand (CBOD), ...

. The "trickling action" of the wastewater through the media dissolves oxygen into the wastewater, ensuring the treatment environment is aerobic for rapid decomposition of organic substances. Vermifilters are most commonly used for

sewage treatment Sewage treatment is a type of wastewater treatment which aims to remove contaminants from sewage to produce an effluent that is suitable to discharge to the surrounding environment or an intended reuse application, thereby preventing water p ...

and for agro-

industrial wastewater treatment Industrial wastewater treatment describes the processes used for Wastewater treatment, treating wastewater that is produced by industries as an undesirable by-product. After treatment, the treated industrial wastewater (or effluent) may be reus ...

. Vermifilters can be used for

primary Primary or primaries may refer to: Arts, entertainment, and media Music Groups and labels * Primary (band), from Australia * Primary (musician), hip hop musician and record producer from South Korea * Primary Music, Israeli record label Work ...

, secondary and

tertiary Tertiary (from Latin, meaning 'third' or 'of the third degree/order..') may refer to: * Tertiary period, an obsolete geologic period spanning from 66 to 2.6 million years ago * Tertiary (chemistry), a term describing bonding patterns in organic ch ...

treatment of sewage, including blackwater and

greywater Greywater (or grey water, sullage, also spelled gray water in the United States) refers to domestic wastewater generated in households or office buildings from streams without fecal contamination, i.e., all streams except for the wastewater fro ...

in on-site systems and municipal wastewater in large centralised systems. Vermifilters are used where wastewater requires treatment before being safely discharged into the environment. Treated effluent is disposed of to either surface or

subsurface In geology, bedrock is solid rock that lies under loose material (regolith) within the crust of Earth or another terrestrial planet. Definition Bedrock is the solid rock that underlies looser surface material. An exposed portion of bedro ...

leach fields. Solid material (such as fecal matter and toilet paper) is retained, de-watered and digested by bacteria and

earthworms An earthworm is a soil-dwelling terrestrial animal, terrestrial invertebrate that belongs to the phylum Annelida. The term is the common name for the largest members of the class (biology), class (or subclass (biology), subclass, depending on ...

into

humus In classical soil science, humus is the dark organic matter in soil that is formed by the decomposition of plant and animal matter. It is a kind of soil organic matter. It is rich in nutrients and retains moisture in the soil. Humus is the Lati ...

that is integrated into the filtration media. The liquid passes through the filtration media where the attached aerobic microorganisms

biodegrade Biodegradation is the breakdown of organic matter by microorganisms, such as bacteria and fungi. It is generally assumed to be a natural process, which differentiates it from composting. Composting is a human-driven process in which biodegradati ...

pathogens and other

organic compound Some chemical authorities define an organic compound as a chemical compound that contains a carbon–hydrogen or carbon–carbon bond; others consider an organic compound to be any chemical compound that contains carbon. For example, carbon-co ...

s, resulting in treated wastewater. Vermifiltration is a low-cost aerobic wastewater treatment option. Because energy is not required for aeration, vermifilters can be considered " passive treatment" systems (pumps may be required if gravity flow is not possible). Another advantage is the high treatment efficiency given the low space requirement.

Terminology

Alternative terms used to describe the vermifiltration process include aerobic biodigester, biological filter with

earthworm An earthworm is a soil-dwelling terrestrial invertebrate that belongs to the phylum Annelida. The term is the common name for the largest members of the class (or subclass, depending on the author) Oligochaeta. In classical systems, they we ...

s, or wet

vermicomposting Vermicompost (vermi-compost) is the product of the decomposition process using various species of worms, usually Eisenia foetida, red wigglers, Enchytraeus buchholzi, white worms, and other earthworms, to create a mixture of decomposing vegetable ...

. The treatment system may be described using terms such as vermi-digester and vermi-trickling filter. When this kind of

sanitation Sanitation refers to public health conditions related to clean drinking water and treatment and disposal of human excreta and sewage. Preventing human contact with feces is part of sanitation, as is hand washing with soap. Sanitation systems ...

system is used to treat only the mixture of excreta and water from flush toilets or pour-flush toilets (called blackwater) then the term "toilet" is added to the name of the process, such as

vermifilter toilet Vermifilter toilet, also known as a primary vermifilter, vermidigester toilet, tiger toilet or tiger worm toilet, is an on-site sanitation system in which human excreta are delivered from a toilet (usually by flushing) onto a medium containing a wo ...

Overview

Vermifiltration was first advocated by researchers at the University of Chile in 1992 as a low-cost sustainable technology suitable for decentralised sewage treatment in rural areas.Meiyan Xing, Xiaowei Li and Jian Yang
Treatment performance of small-scale vermifilter for domestic wastewater and its relationship to earthworm growth, reproduction and enzymatic activity
African Journal of Biotechnology, November 2010 Vermifilters offer treatment performance similar to conventional decentralised wastewater treatment systems, but with potentially higher hydraulic processing capacities. Vermifilters are a type of wastewater treatment

biofilter Biofiltration is a pollution control technique using a bioreactor containing living material to capture and biologically degrade pollutants. Common uses include processing waste water, capturing harmful chemicals or silt from surface runoff, a ...

trickling filter A trickling filter is a type of wastewater treatment system. It consists of a fixed bed of some material, such as rocks, coke, gravel, slag, polyurethane foam, sphagnum peat moss, ceramic, or plastic media, over which sewage or other wastewa ...

, but with the addition of

to improve treatment efficiency. Vermifilters provide an aerobic environment and wet substrate that facilitates microorganism growth as a

biofilm A biofilm is a Syntrophy, syntrophic Microbial consortium, community of microorganisms in which cell (biology), cells cell adhesion, stick to each other and often also to a surface. These adherent cells become embedded within a slimy ext ...

. Microorganisms perform biochemical degradation of organic matter present in wastewater. Earthworms regulate microbial biomass and activity by directly or/and indirectly grazing on microorganisms. Biofilm and organic matter consumed by composting earthworms is then digested into biologically inert castings (humus). The vermicast is incorporated into the media substrate, slowly increasing its volume. When this builds up, it can be removed and applied to soil as an amendment to improve soil fertility and structure. Microorganisms present are

heterotroph A heterotroph (; ) is an organism that cannot produce its own food, instead taking nutrition from other sources of organic carbon, mainly plant or animal matter. In the food chain, heterotrophs are primary, secondary and tertiary consumers, but ...

ic and

autotroph An autotroph is an organism that can convert Abiotic component, abiotic sources of energy into energy stored in organic compounds, which can be used by Heterotroph, other organisms. Autotrophs produce complex organic compounds (such as carbohy ...

ic. Heterotrophic microorganisms are important in oxidising carbon (decomposition), whereas autotrophic microorganisms are important in nitrification. As a result of oxidation reactions, biodegradation and microbial stimulation by enzymatic action, organic matter decomposition and pathogen destruction occurs in the vermifilter. In a study where municipal wastewater was treated in a vermifilter, removal ratios for

biochemical oxygen demand Biochemical oxygen demand (also known as BOD or biological oxygen demand) is an analytical parameter representing the amount of dissolved oxygen (DO) consumed by aerobic bacteria growing on the organic material present in a water sample at a s ...

(BOD₅) were 90%,

chemical oxygen demand In environmental chemistry, the chemical oxygen demand (COD) is an indicative measure of the amount of oxygen that can be consumed by reactions in a measured solution. It is commonly expressed in mass of oxygen consumed over volume of solution, wh ...

(COD) 85%,

total suspended solids Total suspended solids (TSS) is the dry-weight of suspended particles, that are not dissolved, in a sample of water that can be trapped by a filter that is analyzed using a filtration apparatus known as sintered glass crucible. TSS is a water qu ...

(TSS) 98%,

ammonia Ammonia is an inorganic chemical compound of nitrogen and hydrogen with the chemical formula, formula . A Binary compounds of hydrogen, stable binary hydride and the simplest pnictogen hydride, ammonia is a colourless gas with a distinctive pu ...

nitrogen 75% and fecal coliforms eliminated to a level that meets World Health Organisation guidelines for safe re-use in crops.

Process types

Vermifilters can be used for

, secondary and

treatment of blackwater and

Primary treatment of blackwater

Vermifilters can be used for aerobic

primary treatment Sewage treatment is a type of wastewater treatment which aims to remove contaminants from sewage to produce an effluent that is suitable to discharge to the surrounding environment or an intended reuse application, thereby preventing water p ...

of domestic blackwater.Rajiv K. Sinha, Gokul Bharambe, Uday Chaudhari. Sewage treatment by vermifiltration with synchronous treatment of sludge by earthworms: a low-cost sustainable technology over conventional systems with potential for decentralization, Environmentalist, 2008 28:409-420 Untreated blackwater enters a ventilated enclosure above a bed of filter medium. Solids accumulate on the surface of the filter bed while liquid drains through the filter medium and is discharged from the reactor. The solids (feces and toilet paper) are aerobically digested by aerobic bacteria and composting earthworms into castings (humus), thereby significantly reducing the volume of organic material. Twin chamber primary vermifilter

Primary treatment vermifilter reactors are designed to digest solid material, such as contained in raw sewage. Twin-chamber parallel reactors offer the advantage of being able to allow one to rest, while the other is active, in order to facilitate hygienic removal of humus with reduced pathogen levels. Worms actively digest the solid organic material. Over time, an equilibrium is reached in which the volume digested by a stable population of worms is equal to the input volume of solid waste. Seasonal and environmental factors (such as temperature) and variable influent volumes can cause buildup of solid waste as a pile. Although oxygen is excluded from the centre of this "wet" compost pile, worms work from the outside in and introduce air as necessary into the pile to meet their nutritional requirements. This food resource buffer ensures primary treatment vermifilters have a level of resilience and reliability, provided space is provided for a pile to build up. There is some evidence that the wet environment facilitates digestion of solid waste by worms.C. Furlong, W. T. Gibson, M. R. Templeton, M. Taillade, F. Kassam, G. Crabb, R. Goodsell, J. McQuilkin, A. Oak, G. Thakar, M. Kodgire, R. Patankar
The development of an onsite sanitation system based on vermifiltration: the "Tiger Toilet"
Journal of Water, Sanitation and Hygiene for Development, January 2015 The volume of vermicast humus increases only slowly and occasionally needs to be removed from the primary treatment reactor. Primary treatment of wet mixed blackwater can also include

containing food solids, grease and other

biodegradable waste Biodegradable waste includes any organic matter in waste which can be broken down into carbon dioxide, water, methane, compost, humus, and simple organic molecules by micro-organisms and other living things by composting, aerobic digestion, ana ...

. Solid material is reduced to stable humus (worm castings), with volume reductions of up to tenfold.C. Furlong, M.R. Templeton, W.T. Gibson
Processing of human faeces by wet vermifiltration for improved on-site sanitation
Journal of Water, Sanitation and Hygiene for Development 4(2):231, June 2014 The process produces primary treated blackwater, with much of the solid organic material removed from the effluent. Because liquid effluent is discharged almost immediately on entering the digester, little dissolved oxygen is consumed by the wastewater through the filtration stage. However, oxygen demand is leached into the wastewater flow through the filter as worms digest the retained solids.Taylor, M. Clarke, W. P., Greenfield, P. F. The treatment of domestic wastewater using small-scale vermicompost filter beds, Journal of Ecological Engineering, December 2003 21: 197–203 This oxygen demand can be removed with secondary treatment vermifilter reactors. Primary treatment vermifilters provide a similar level of liquid effluent treatment to a septic tank, but in less time because digestion of solids by worms takes place rapidly in an aerobic environment. The liquid effluent is either discharged directly to a drain field or undergoes

secondary treatment Secondary treatment (mostly biological wastewater treatment) is the removal of Biodegradation, biodegradable organic matter (in solution or suspension) from sewage or similar kinds of wastewater. The aim is to achieve a certain degree of effluent ...

before being used for surface or subsurface irrigation of agricultural soil.

Secondary treatment

Secondary and tertiary treatment vermifilters can be underneath the primary vermifilter in a single tower, but are typically single reactors, where several reactors can be chained in series as sequential vermifilters. Drainage within the reactor is provided by filter media packed according to the

hydraulic conductivity In science and engineering, hydraulic conductivity (, in SI units of meters per second), is a property of porous materials, soils and Rock (geology), rocks, that describes the ease with which a fluid (usually water) can move through the porosity, ...

and permeability of each material that is present within the vermifilter. The filter packing retains the solid particles present in the effluent wastewater, increases the hydraulic retention time and also provides a suitable habitat for sustaining a population of composting earthworms. This population requires adequate moisture levels within the filter media, but also adequate drainage and oxygen levels. Sprinklers or drippers can be used in secondary and tertiary treatment vermifilter reactors (see image). Hydraulic factors (hydraulic retention time, hydraulic loading rate and organic loading rate) and biological factors (earthworm numbers, levels of biofilm) can influence treatment efficiency.

Design

Vermifilters are enclosed reactors made from durable materials that eliminate the entry of

vermin Vermin (colloquially varmint(s) or varmit(s)) are pests or nuisance animals that spread diseases and destroy crops, livestock, and property. Since the term is defined in relation to human activities, which species are included vary by regi ...

, usually plastic or concrete. Ventilation must be sufficient to ensure an

environment for the worms and microorganisms, while also inhibiting entry of unwanted

flies Flies are insects of the Order (biology), order Diptera, the name being derived from the Ancient Greek, Greek δι- ''di-'' "two", and πτερόν ''pteron'' "wing". Insects of this order use only a single pair of wings to fly, the hindwin ...

. Temperature within the reactor needs to be maintained within a range suitable for the species of compost worms used.

Influent entry

Influent entry is from above the filter media. Full-flush toilets can have the entry point into the side of the reactor, whereas micro-flush toilets, because these do not provide sufficient water to convey solids through sewer pipes, are generally installed directly above the reactor. For primary treatment reactors, sufficient vertical space must be provided for growth of the pile. This is dependent on the volume of solids in the influent and the presence of slower decomposing materials such as toilet paper. Secondary and tertiary treatment reactors can use sprinklers or tricklers to distribute the influent wastewater evenly over the filter media to improve treatment efficiency of the filter media. Generic domestic vermifilter

Filter substrate

Drainage within the vermifilter reactor is provided by the filter media. The filter media has the dual purpose of retaining the solid organic material, while also providing a habitat suitable for sustaining a population of

composting worms Vermicompost (vermi-compost) is the product of the decomposition process using various species of worms, usually red wigglers, white worms, and other earthworm An earthworm is a soil-dwelling terrestrial invertebrate that belongs to the ...

. This population requires adequate moisture levels within the media, along with good drainage and aerobic conditions. Vermifilter reactors may comprise a single section packed only with organic media, or up to three filter sections comprising an

organic Organic may refer to: * Organic, of or relating to an organism, a living entity * Organic, of or relating to an anatomical organ Chemistry * Organic matter, matter that has come from a once-living organism, is capable of decay or is the product ...

top layer that provides habitat for the earthworms, an

inorganic An inorganic compound is typically a chemical compound that lacks carbon–hydrogen bonds⁠that is, a compound that is not an organic compound. The study of inorganic compounds is a subfield of chemistry known as '' inorganic chemistry''. Inor ...

upper layer of sand and lower layer of gravel. The filter sits on top of a sump or drainage layer of coarse gravel, rocks or pervious plastic drainage coil where the treated effluent is discharged and/or recirculated to the top of the reactor. Alternatively the filter media may be suspended above the sump in a basket.

Synthetic Synthetic may refer to: Science * Synthetic biology * Synthetic chemical or compound, produced by the process of chemical synthesis * Synthetic elements, chemical elements that are not naturally found on Earth and therefore have to be created in ...

geotextile Geotextiles are versatile permeable fabrics that, when used in conjunction with soil, can effectively perform multiple functions, including separation, filtration, reinforcement, protection, and drainage. Typically crafted from polypropylene or ...

cloth is sometimes used to retain the filter media in place above the drainage layer. To remain aerobic, adequate ventilation must be provided, along with an outlet for the liquid effluent to drain away. Common filter packing materials include

sawdust Sawdust (or wood dust) is a by-product or waste product of woodworking operations such as sawing, sanding, milling and routing. It is composed of very small chips of wood. These operations can be performed by woodworking machinery, portable p ...

,Arora, S., Rajpal, A., Kazmi, A.A., 2016. Antimicrobial Activity of Bacterial Community for Removal of Pathogens during Vermifiltration. J. Environ. Eng. 142 (5).

wood chips Woodchips are small- to medium-sized pieces of wood formed by cutting or chipping larger pieces of wood such as trees, branches, logging residues, stumps, roots, and wood waste. Woodchips may be used as a biomass solid fuel and are raw materia ...

coir Coir (), also called coconut fibre, is a natural fibre extracted from the outer husk of coconut, and used in products such as floor mats, doormats, brushes, and mattresses. Coir is the fibrous material found between the hard, internal shell ...

bark Bark may refer to: Common meanings * Bark (botany), an outer layer of a woody plant such as a tree or stick * Bark (sound), a vocalization of some animals (which is commonly the dog) Arts and entertainment * ''Bark'' (Jefferson Airplane album), ...

peat Peat is an accumulation of partially Decomposition, decayed vegetation or organic matter. It is unique to natural areas called peatlands, bogs, mires, Moorland, moors, or muskegs. ''Sphagnum'' moss, also called peat moss, is one of the most ...

, and

straw Straw is an agricultural byproduct consisting of the dry wikt:stalk, stalks of cereal plants after the grain and chaff have been removed. It makes up about half of the crop yield, yield by weight of cereal crops such as barley, oats, rice, ry ...

for the organic layer.

Gravel Gravel () is a loose aggregation of rock fragments. Gravel occurs naturally on Earth as a result of sedimentation, sedimentary and erosion, erosive geological processes; it is also produced in large quantities commercially as crushed stone. Gr ...

quartz Quartz is a hard, crystalline mineral composed of silica (silicon dioxide). The Atom, atoms are linked in a continuous framework of SiO4 silicon–oxygen Tetrahedral molecular geometry, tetrahedra, with each oxygen being shared between two tet ...

sand Sand is a granular material composed of finely divided mineral particles. Sand has various compositions but is usually defined by its grain size. Sand grains are smaller than gravel and coarser than silt. Sand can also refer to a textural ...

, round

stones In geology, rock (or stone) is any naturally occurring solid mass or aggregate of minerals or mineraloid matter. It is categorized by the minerals included, its Chemical compound, chemical composition, and the way in which it is formed. Rocks ...

pumice Pumice (), called pumicite in its powdered or dust form, is a volcanic rock that consists of extremely vesicular rough-textured volcanic glass, which may or may not contain crystals. It is typically light-colored. Scoria is another vesicula ...

mud Mud (, or Middle Dutch) is loam, silt or clay mixed with water. Mud is usually formed after rainfall or near water sources. Ancient mud deposits hardened over geological time to form sedimentary rock such as shale or mudstone (generally cal ...

balls, glass balls, ceramsite and

charcoal Charcoal is a lightweight black carbon residue produced by strongly heating wood (or other animal and plant materials) in minimal oxygen to remove all water and volatile constituents. In the traditional version of this pyrolysis process, ca ...

are commonly used for the inorganic layer. The surface area and porosity of these filter materials influence treatment performance. Materials with low granulometry (small particles) and large surface area may improve the performance of the vermifilter but impede its drainage.

Sizing

Vermifilters can be constructed as single tower systems, or separate staged reactors (either gravity or pump operated) for the treatment of wastewater according to design requirements (primary, secondary, tertiary treatment). More stages can increase the degree of treatment because multiple stage systems provide accumulating aerobic conditions suitable for

nitrification ''Nitrification'' is the biological oxidation of ammonia to nitrate via the intermediary nitrite. Nitrification is an important step in the nitrogen cycle in soil. The process of complete nitrification may occur through separate organisms or ent ...

ammonium Ammonium is a modified form of ammonia that has an extra hydrogen atom. It is a positively charged (cationic) polyatomic ion, molecular ion with the chemical formula or . It is formed by the protonation, addition of a proton (a hydrogen nucleu ...

and removal of

COD Cod (: cod) is the common name for the demersal fish genus ''Gadus'', belonging to the family (biology), family Gadidae. Cod is also used as part of the common name for a number of other fish species, and one species that belongs to genus ''Gad ...

The design parameters of vermifilters include stocking density of earthworms (although over time earthworm population tends to be self-moderating), filter media composition, hydraulic loading rate,

hydraulic retention time The residence time of a fluid parcel is the total time that the parcel has spent inside a control volume (e.g.: a chemical reactor, a lake, a human body). The residence time of a set of parcels is quantified in terms of the frequency distribution ...

and organic loading rate. Hydraulic retention time and hydraulic loading rate both affect effluent quality. Hydraulic retention time is the actual time the wastewater is in contact with the filter media and is related to the depth of the vermifilter (which may increase over time due to the accumulation of earthworm vermicastings), reactor volume and type of material used (porosity). The hydraulic retention time determines wastewater inflow rate (hydraulic loading as influent volume per hour). In principle, provided the environment is aerobic, the longer the wastewater remains inside the filter, the greater the BOD₅ and COD removal efficiency will be, but at the expense of hydraulic loading. Wastewater requires sufficient contact time with the biofilm to allow for the adsorption, transformation, and reduction of contaminants. The hydraulic loading rate is an essential design parameter, consisting of the volume of wastewater that a vermifilter can reasonably treat in a given amount of time. For a given system, higher hydraulic loading rates will cause hydraulic retention time to decrease and therefore reduce level of treatment. Hydraulic loading rate may depend on parameters such as structure, effluent quality and bulk density of filter packing, along with method of effluent application.Siegrist, R.L., 1987. Soil Clogging During Subsurface Wastewater Infiltration as Affected by Effluent Composition and Loading Rate. J. Environ. Qual. 16(2): 181-187. Common hydraulic retention time values in vermifiltration systems range from 1 to 3 hours. Hydraulic loading rates commonly vary between 0.2 m³m⁻²day⁻¹, 3.0 m³m⁻²day⁻¹ or 10–20 g L⁻¹.Lourenço, N., Nunes, L.M. (2017
Optimization of a vermifiltration process for treating urban wastewater
Volume 100, March 2017, Pages 138–146 Organic loading rate is defined as the amount of soluble and particulate organic matter (as BOD₅) per unit area per unit time. Treatment efficiency is influenced by health, maturity and population abundance of the earthworms. Abundance is a fundamental parameter for efficient operation of a vermifiltration system. Different values are reported in the literature, usually in grams or number of individuals per volume of filter packing or surface area of filter packing. Common densities vary between 10 g L⁻¹ and 40 g L⁻¹ of filter packing material. An abundance of earthworms improves treatment efficiency, in particular BOD₅, TSS and NH₄⁺ removal. This is because earthworms release organic matter into the filter media and stimulate nitrogen mineralization. Earthworm castings may have substances which contribute to higher BOD₅ removal.Lourenço, N., Nunes, L.M., Submitted. Optimization of a vermifiltration process for treating urban wastewater. Ecological Engineering.

Operation and maintenance

A vermifilter has low mechanical and manual maintenance requirements, and, where gravity operated, requires no energy input. Recirculation, if required for improved effluent quality, would require a pump. Occasional topping up of organic materials may be required as these decompose and reduce in volume. The volume of

worm castings Vermicompost (vermi-compost) is the product of the decomposition process using various species of worms, usually red wigglers, white worms, and other earthworms, to create a mixture of decomposing vegetable or food waste, bedding materials, and ...

increases only slowly and occasionally

vermicompost Vermicompost (vermi-compost) is the product of the decomposition process using various species of worms, usually red wigglers, white worms, and other earthworms, to create a mixture of decomposing vegetable or food waste, bedding materials, and ...

needs to be removed from the vermifilter. Solids accumulate on the surface of the organic filter media (or filter packing). The liquid fraction drains through the medium into the sump or equaliser and is either discharged from the reactor or recirculated to the top for further treatment. Wastewater is discharged to the surface of the filter material by direct application or by sprinklers, drippers or tricklers.

Examples

* Construction of primary and secondary domestic vermifilters from readily available materials *A household pour-flush toilet, with combined primary vermifiltration and direct effluent infiltration into the soil below, is called the "Tiger Toilet" and has been tested by Bear Valley Ventures and Primove Infrastructure Development Consultants in rural India. Unlike a

pit latrine A pit latrine, also known as pit toilet, is a type of toilet that collects human waste in a hole in the ground. Urine and feces enter the pit through a drop hole in the floor, which might be connected to a toilet seat or squatting pan for user ...

, it was found that there was virtually no accumulation of fecal material over a one-year period. In the effluent, there was a 99% reduction in

fecal coliforms A fecal coliform (British: faecal coliform) is a facultatively anaerobic, rod-shaped, gram-negative, non- sporulating bacterium. Coliform bacteria generally originate in the intestines of warm-blooded animals. Fecal coliforms are capable of growth ...

. User satisfaction is high, driven mainly by a lack of odour. This system is now being marketed commercially in India, where over 2000 of these toilets and treatment systems had been sold and installed by May 2017. * "Tiger worm toilets" are also being promoted by

Oxfam Oxfam is a British-founded confederation of 21 independent non-governmental organizations (NGOs), focusing on the alleviation of global poverty, founded in 1942 and led by Oxfam International. It began as the Oxford Committee for Famine Relief ...

as a

solution in refugee camps, slums and

peri-urban Peri-urbanisation relates to the processes of scattered and dispersive urban growth that create hybrid landscapes of fragmented and mixed urban and rural characteristics. Such areas may be referred to as the rural–urban fringe, the outskirts ...

areas in Africa, for example in

Liberia Liberia, officially the Republic of Liberia, is a country on the West African coast. It is bordered by Sierra Leone to Liberia–Sierra Leone border, its northwest, Guinea to Guinea–Liberia border, its north, Ivory Coast to Ivory Coast–Lib ...

. * Low-flush vermifilter toilet systems with direct subsoil soakage are being marketed in Ghana and other African countries by the Ghana Sustainable Aid Project (GSAP) with support by Providence College in the U.S. and the University of Ghana. * Biofilcom is a company active in Ghana which is marketing the process under the name of "Biofil Digester". * In Australia and New Zealand, there are numerous suppliers offering vermifilter systems for domestic greywater and/or blackwater treatment, with primary treated effluent disposal to subsurface leach fields. Examples include Wormfarm, Zenplumb, Naturalflow, SWWSNZ and Autoflow. *

Vermifilter toilet Vermifilter toilet, also known as a primary vermifilter, vermidigester toilet, tiger toilet or tiger worm toilet, is an on-site sanitation system in which human excreta are delivered from a toilet (usually by flushing) onto a medium containing a wo ...

References

External links

Innoqua
Project—combines vermifilters and filters using Daphnia, microalgae, and other organisms to treat wastewater and has thi
summary of vermifilters
. {{wastewater Sanitation