Alkaline hydrolysis (also called biocremation, resomation,^[1][2] flameless cremation,^[3] aquamation^[4] or water cremation^[5]) is a process for the disposal of human and pet remains using lye and heat, and is an alternative to burial or cremation.

The process is based on alkaline hydrolysis: the body is placed in a pressure vessel that is then filled with a mixture of water and potassium hydroxide, and heated to a temperature around 160 °C (320 °F), but at an elevated pressure, which prevents boiling. Instead, the body is effectively broken down into its chemical components, which takes approximately four to six hours. A lower temperature and pressure may be used, but for a longer duration (98 °C (208 °F), 14 to 16 hours).^[6] At the beginning of the process, the mixture is very alkaline, with a pH level of approximately 14; pH drops to 11 by the end, but the final pH level depends on the total operation time and the amount of fat in the body.^[7]

The result is a quantity of green-brown tinted liquid (containing amino acids, peptides, sugars and salts) and soft, porous white bone remains (calcium phosphate) easily crushed in the hand (although a cremulator is more commonly used) to form a white-colored dust. The "ash" can then be returned to the next of kin of the deceased. The liquid is disposed of either through the sanitary sewer system, or through some other method, including use in a garden or green space.^[8] To dispose of 1,000 pounds (450 kg) of biomass, approximately 60–240 US gallons (230–910 L; 50–200 imp gal) of water are used, resulting in 120–300 US gallons (450–1,140 L; 100–250 imp gal) of effluent, which carries a dried weight (inorganic and mineral content) of 20 pounds (9.1 kg) (approximately 2% of original weight).^[7]

This alkaline hydrolysis process has been championed by a number of ecological campaigning groups,^[9] for using 90 kWh of electricity,^[10] one-quarter the energy of flame-based cremation, and producing less carbon dioxide and pollutants.^[1][5] It is being presented as an alternative option at some British crematorium sites.^[11] As of August 2007^[update], about 1,000 people had chosen this method for the disposal of their remains in the United States.^[12] The operating cost of materials, maintenance, and labor associated with the disposal of 2,000 pounds (910 kg) of remains was estimated at $116.40,^[7] excluding the capital investment cost of equipment.

Alkaline hydrolysis has also been adopted by the pet and animal industry. A handful of companies in North America offer the procedure as an alternative to pet cremation.^[13] Alkaline hydrolysis is also used in the agricultural industry to sterilize animal carcasses that may pose a health hazard, because the process inactivates viruses, bacteria, and prions that cause transmissible spongiform encephalopathy.^[7][14][15]

In Christian countries and cultures, cremation has historically been discouraged and viewed as a desecration of God's image, and as interference with the resurrection of the dead taught in scripture. It is now acceptable to some denominations.^[19] Desmond Tutu, former Anglican Archbishop of Cape Town, was aquamated, per his wish.^[20] The Eastern Orthodox Church does not allow cremation.

The Roman Catholic Church allows cremation of bodies as long as it is not done in denial of the beliefs in the sacredness of the human body or the resurrection of the dead.^[21] In 2008, Renée Mirkes published the first Catholic moral analysis of alkaline hydrolysis.^[22][23] He argued that it is morally neutral and may be an alternative to burial on similar grounds to cremation.^[23] However, the Catholic Church in the United States does not approve of alkaline hydrolysis as a method of final disposal of human remains. In 2011, Donald Cardinal Wuerl, Archbishop of Washington and then chairman of the Committee on Doctrine of the United States Conference of Catholic Bishops (USCCB), determined it "unnecessarily disrespectful of the human body."^[24] The Archdiocese of St. Louis explained that it was considered this way because the Church took concern with the final disposal of the liquid solution, which is typically to the sewer system.^[25] This was considered disrespectful of the sanctity of the human body.^[25] Additionally, when alkaline hydrolysis was proposed in New York state in 2012, the New York State Catholic Conference condemned the practice, stating that hydrolysis does not show sufficient respect for the teaching of the intrinsic dignity of the human body.^[26]

Judaism forbids cremation as it is not in line with the religion’s teachings of respect and dignity for humans, who are believed by the religion to be created in God’s image. Islam also forbids cremation of the deceased. Both religions are likely to reject alkaline hydrolysis as they believe that the body must be laid to rest through burial in order to prepare for the afterlife.^[22] The Bahá'í Faith, like other Abrahamic religions, discourages cremation of the deceased. The human body is seen as having to be treated with respect, and merely wrapped in a shroud before burial no further than an hour from the place of death.

Sikhism, Hinduism, and Buddhism each place theological emphasis on the burning of the corpse which may prevent alkaline hydrolysis from replacing cremation.^[22]

Native Hawaiians consider aquamation a way to approximate their traditional burial ritual, which involves removing the bones (iwi) cleanly from the flesh using a beachside underground oven (imu), wrapping the bones, and hiding them. The use of an imu on human bodies is no longer allowed, but aquamation may offer an alternative as it produces similarly clean bones.^[27]

• Burial
• Promession
• Human composting