Farm waste recycling 

The farm wastes may be liquid semisolid or solid. Some wastes may be treated primarily as sewage and the residues emanating from the digestion tank serve as manure. The sludge from the primary sedimentation tank could be disposed by land bury or by composting while the liquid effluent after the separation of activated sludge in the secondary sedimentation tank is disposed to courses. Besides, the sludge may also be disposed in the sea, used as compost or spread over land. The effluent from secondary setting tank (of sewage), that is disposed into water courses such as rivers and streams should be diluted at least 8:1 (water: effluent) in manner that it should not contain more than 10mg/l of suspended solids and 10mg/l of BOD.

Oxidation pond- It is an open shallow pool 1-1.5m deep with an inlet and out let. It functions is the presence of algae certain types of bacteria (which feed in decaying organic matter) and sunlight. The organic matter is oxidized by bacteria and produce CO2, ammonia, and water. The algae with the help of sunlight utilizes CO2, water and organic minerals for their growth and liberated O2 which together induces the process of oxidation in the pond. During sunshine the pond functions aerobically and during night, the bottom layer becomes anaerobic. Twenty-two acres of land is required for developing an oxidation pond. It can become a profitable method of sewage purification for a small community.

With the use of mechanical rotors for extended aeration, the aerated lagoons can also be used for purification of sewage and wastes generated by townships with 5,000 to 20,000 population. Only one acre of land is required for developing an oxidizing ditch and 2.5acres for aerated lagoon. A slurry from a dairy herd of 50 cows and their litters can cause a potential pollution load which is equivalent to that of a village of 1000 people. It the slurry (semi liquid) consisting of faeces and urine suspended in water and occasional bedding and other wastes is diluted; it can be passes through pipeline and gun system with enhanced efficiency of use of sewage disposal system.

It has been estimated that about 80% of livestock units will continue to handle wastes in the traditional manner and only those with little land may have to use more sophisticated systems for handling wastes.

Collection of wastes- Dung, soiled bedding, feed wastes, urine etc. forming solid wastes and urine and waste water constituting liquid manure can be collected separately or flushed out together with plenty of water through hose pipes. The drains from each shed may join the main farm drain leading the liquid wastes to the sewerage system. Solid manure is to be collected and removed from the shed at least twice daily and should be stored in manure pit with impervious walls which is located at a minimum distance of 10m from a well, river, tank or boundary of an adjoining land property to safeguard against the menance of foul odors and flies.

Types of manure or solid wastes- The production of manure is on a average 40kg per day per one adult unit (one cattle or buffalo above three yrs. of age). One calf below one yr. Or one adult sheep or goat or pig produces manure roughly equal to 1/3 of an adult unit.

Aggregates of small globules are voided by sheep and goats, which are quite hard and can be swept of floor. For pig paddock, 0.5m wide trench covered with slats or iron grills can be provided along the outer border where the animals will void the faeces which will drop through the grill to fall at the bottom of the trench. From where, it can be easily collected periodically.

Manure pit- Simple manure pit for villages con be constructed on and elevated land by digging 4x3 square meter pit 2meter depth with a roof. The main objective is to prevent entry of rainwater into the pit to overcome leaching of plant nutrients and to desiccate the manure quickly to dung cake. This pit as usually would have roof at a height permitting free circulation of air over the manure preventing leaching of valuable plant nutrients and also prevents anaerobic conditions causing detiorating of manure. The manure is well turned periodically to ensure uniform decomposition of fresh manure that is added to the pit daily. It will be essential for destruction of eggs and larvae of parasites.

Composting- Rctangular pits of 3x2x1.5m are dug. A layer of straw, animal bedding, garbage and leaves is first put in the pit digested slurry is then allowed to flow into the pit. Alternate layers of refuse and slurry are laid unfit the pit is full. Bamboo poles having holes 10cm apart are placed in the compos table material materials for aeration and finally the pit is plastered with a mud layer. This will minimized the loss of nitrogen from the pit. The compost of such manure is used only after 3-4,pmtjs/

Compost heaps- Digested slurry and refuse are mixed in equal proportion and a pile is built of about 2.5m in width base, 3.5m in length and 1.o m in height. The sides are tapered so the tip becomes narrower by 0.5m in length and width than the base. The heap is plastered with a thin layer of mud and kept protected from rain. The heap may be turned up side down very 15days. Water can be sprinkled if it dried up. In this way compost will be ready in two months.

Semi-dried slurry- This slurry is spread in shallow pits and allowed to dry, scrapped, piled and covered with plastic sheets till used in the field.

Biogas plant- At village or farm level, the disposal of farmyard manure can be utilized for production of biogas, fertilizer (for crops in liquid form) or compost.

Dung, urine and water are mixed in a tank the mixture known as slurry is allowed to pass through the inlet into the digester. The slurry ferments in the absence of air and produces biogas. The digested slurry is used as manure either directly or after composting along with other available agro farm wastes. The slurry from the biogas plant is good quality manure free from weeds, seeds, pathogens and foul smell. About 20% of total nitrogen present in the digested slurry is in ammonia form which is readily available for the crops.

Liquid manuring- When the slurry from the biogas plant is used in liquid form as it comes out, it can be easily distributed in the field by linking the out lets with the main irrigation channel or through an appropriate handling system, e.g., bullock cart carrying oil drums or buckets filled with liquid slurry.

Slurry filter bed- A bed with a size of 3x1.2x0.6m with opening at opposite end of the slopping bottom is constructed. The digested slurry is led through a channel to flow and cover a 15cm compact layer of green/dry leaves in the bed. Water from slurry filters down and flows out of the opening into a pit. Semisolid residues left on the top of the bed has the consistency of fresh dung and can be used in the field as fertilizer.

Manuring fish ponds- Some areas farmers are utilizing digested slurry with equal quantity of mustard oil seed cake and bran as an ideal supplementary feed for singi fish and also for fertilizing the fish pond at a rate of 35% of the body weight of the fish, to reduce the cost of supplementary fish feed.