Mechanical composters: powered aerobic units that convert wet waste on site.

A pit relies on time, area and natural aeration; a mechanical composter uses a shredder, an agitator and controlled aeration inside an enclosed vessel to compress the active phase into a short cycle within a small footprint. The pit is cheaper but needs land and tolerates odour and pests poorly in a built-up premises. The machine costs more to buy and run but is the practical option where space is the constraint.

No. Most mechanical composters discharge a stabilised, partially decomposed pre-compost that still needs a curing or maturation period (typically a few weeks in covered, ventilated bays) before it is mature enough to use on plants. Installations that skip curing produce a material that damages landscaping and gives the whole system a bad name.

A bulking agent (cocopeat, sawdust or dried shredded garden waste) to correct moisture and carbon balance, and a microbial culture or inoculum to seed the process. Consumption tracks the wet-waste load, so it should be budgeted as a running cost rather than treated as a one-time supply. The bulking agent also needs dry covered storage on site.

A correctly loaded and correctly aerated aerobic unit should not produce a strong odour; persistent smell usually signals excess moisture, a shortfall of bulking agent, overloading beyond rated capacity, or anaerobic pockets from poor mixing. Odour is therefore a useful diagnostic, and it is what a housing society will judge the installation on within the first month.

The measured wet-waste generation in kg per day, allowing for the peak day rather than the average, plus the cycle time the equipment needs. Segregation quality matters as much as quantity: if plastics, glass and packaging arrive with the wet waste, effective throughput falls and the shredder suffers, so segregation discipline is part of the sizing assumption.

The generator remains responsible for compliance under the Solid Waste Management Rules 2016, that obligation cannot be transferred to a supplier. Day-to-day operation is usually done by trained housekeeping staff, with the supplier or a contractor holding an annual maintenance contract for the mechanical and electrical side. The split should be written into the contract so that neither party assumes the other is doing the daily loading and record-keeping.

Routine cleaning of the feed and discharge points, checking and greasing of the drive and agitator, inspection of the shredder blades, and periodic attention to heaters, blowers and the odour-control media where fitted. Blades and bearings are wear items with a finite life. An annual maintenance contract with defined visit frequency and response time is the normal arrangement.