Perspectives, and (original) (raw)

Anaerobic Processes as the Core Technology for Sustainable Domestic Wastewater Treatment: Consolidated Applications, New Trends, Perspectives, and Challenges

Reviews in Environmental Science and Bio/Technology, 2006

Anaerobic digesters have been responsible for the removal of large fraction of organic matter (mineralization of waste sludge) in conventional aerobic sewage treatment plants since the early years of domestic sewage treatment (DST). Attention on the anaerobic technology for improving the sustainability of sewage treatment has been paid mainly after the energy crisis in the 1970s. The successful use of anaerobic reactors (especially up-flow anaerobic sludge blanket (UASB) reactors) for the treatment of raw domestic sewage in tropical and sub-tropical regions (where ambient temperatures are not restrictive for anaerobic digestion) opened the opportunity to substitute the aerobic processes for the anaerobic technology in removal of the influent organic matter. Despite the success, effluents from anaerobic reactors treating domestic sewage require post-treatment in order to achieve the emission standards prevailing in most countries. Initially, the composition of this effluent rich in reduced compounds has required the adoption of post-treatment (mainly aerobic) systems able to remove the undesirable constituents. Currently, however, a wealth of information obtained on biological and physical-chemical processes related to the recovery or removal of nitrogen, phosphorus and sulfur compounds creates the opportunity for new treatment systems. The design of DST plant with the anaerobic reactor as core unit coupled to the pre-and post-treatment systems in order to promote the recovery of resources and the polishing of effluent quality can improve the sustainability of treatment systems. This paper presents a broader view on the possible applications of anaerobic treatment systems not only for organic matter removal but also for resources recovery aiming at the improvement of the sustainability of DST.

Anaerobic technology harnessed fully by using different techniques: Review

Clean Energy and Technology ( …, 2011

In today's energy demanding life style, there is need for new sources of energy which are renewable as well as eco friendly because the climate change is one of the biggest challenges for mankind. Many countries initiated production and distribution of several renewable energy technologies to solve the energy problem in rural areas. In India, the per capita energy consumption is 400 KWH per annum, while 350 kgoe per capita primary commercial energy consumption and about 80% of total rural energy consumption comes from non commercial energy like firewood, agricultural waste, dry cow dung cakes. Among several technologies the anaerobic digestion technology, has been proved to be viable and emerged as a promising technology because biomass is available as domestic resources in India (biomass availability in India is of 150 million MT per annum), require less capital investment and per unit production cost as compare to other renewable energies. The another major issue is to reduce the emission of greenhouse gasses and this could be solved by anaerobic digestion technology (1 kg biomethane is equivalent to the reduction of 25 kg CO2) with various advantages like; replace the fossil fuels, reduce or eliminate the energy footprint of waste treatment plants, reduce methane emission from landfills, replace the industrially produced chemical fertilizers etc. Recent life cycle assessment studies have demonstrated that biogas derived methane (biomethane) is one of the most energy efficient and environmentally sustainable way of replacement of fossil fuels in both heat and power generation. In anaerobic digestion other than its merits, certain constraints are also associated with it. Most common among these are the low gas production in winter, low gas production from agricultural residues, large hydraulic retention time and digester design etc. Therefore, need of different techniques to remove its various limitations to achieve optimized gas production and helpful for rural areas. This paper reviews the various techniques, which could be used to solve the constraints occur during the gas production and harnessed fully anaerobic technology.

Anaerobic treatment as a core technology for energy, nutrients and water recovery from source-separated domestic waste(water)

Water science and technology : a journal of the International Association on Water Pollution Research, 2008

Based on results of pilot scale research with source-separated black water (BW) and grey water (GW), a new sanitation concept is proposed. BW and GW are both treated in a UASB (-septic tank) for recovery of CH4 gas. Kitchen waste is added to the anaerobic BW treatment for doubling the biogas production. Post-treatment of the effluent is providing recovery of phosphorus and removal of remaining COD and nitrogen. The total energy saving of the new sanitation concept amounts to 200 MJ/year in comparison with conventional sanitation, moreover 0.14 kg P/p/year and 90 litres of potential reusable water are produced.

Anaerobic Digestion - A sustainable opportunity

2000

The anaerobic digestion process is one of the established technologies for sustainable processing of residues and wastes in the agro-food industry. It can be either used to treat biodegradable wastes or produce saleable products with economical value. This is a natural process where complex organic matter is broken into simpler substances by microorganisms under airless conditions. Anaerobic microorganisms digest the

Anaerobic Digestion for Sustainable Energy : A Brief Review

This paper presents a review on different aspects influencing the development of household anaerobic digesters. Biogas technology has recently been considered as one of the few most promising renewable and sustainable energies. However, there exists certain challenges to household digester's dissemination. Some of these challenges are very critical to the appreciation of anaerobic digestion processes as well as systems. The type of waste, feeding regime, temperature, pressure, retention time, hydrogen ion concentration and the carbon-to-nitrogen ratio are considered to be very important factors for optimum anaerobic digestion processes. The plant sustainability and the quality of anaerobic digestion biproducts are also considered very important during design and implementation stages.

Anaerobic Digestion Process: An Effective Tool for Waste Management and Renewable Energy Production

The quest for a sustainable and effective waste management is highly increasing due to several environmental and economic concerns such as climatic change and diminishing resources of fossil energy and raw materials. Anaerobic digestion (AD) is the most promising alternative for disposal of many different kinds of organic wastes because of its inherent high energy recovery, elimination of greenhouse gases and rendering pathogens and odorous emissions innocuous.AD is a process by which microorganisms break down biodegradable material in the absence of oxygen. It involves four major steps: hydrolysis, acidogenesis, acetogenesis and methanogenesis. Hydrolysis is the rate-limiting step of the overall process degradation. The paper is an overview of the process of AD, its applications and means of enhancement for sustainable waste management and renewable energy production.

Anaerobic digestion for sustainable development: a natural approach

Water science and technology : a journal of the International Association on Water Pollution Research, 2002

After the discovery of methane gas by Alessandro Volta in 1776, it took about 100 years before anaerobic processes for the treatment of wastewater and sludges were introduced. The development of high rate anaerobic digesters for the treatment of sewage and industrial wastewater took until the nineteen-seventies and for solid waste even till the nineteen-eighties. All digesters have in common that they apply natural anaerobic consortia of microorganisms for degradation and transformation processes. In view of this, it could be rewarding to evaluate the efficiency of natural ecosystems for their possible application. Examples of high rate anaerobic natural systems include the forestomach of ruminants and the hindgut of certain insects, such as termites and cockroaches. These 'natural reactors' exhibit volumetric methane production rates as high as 35 l/l.d. The development of anaerobic reactors based on such natural anaerobic systems could produce eco-technologies for the effe...

00 A REVIEW OF THE EVOLUTION AND DEVELOPMENT OF ANAEROBIC DIGESTION TECHNOLOGY

Journal of Engineering and Technology, 2010

The paper is a study of the discovery of anaerobic digestion and its development from waste treatment to biogas-for-energy production technology. Anaerobic digestion dates back to 4000 BC when the Sumerians discovered the process of fermentation. Anecdotal evidences date the use of biogas back to the 10 th century BC when the Assyrians used it for heating bath water. The Persians, also, used biogas for the same purpose during the 16 th century. In 1808, Sir Humphry Davy determined that methane was present in the gases produced during the anaerobic digestion of cattle manure. The first biogas digester was built at a leper colony in Bombay, India in 1859. Anaerobic digestion reached England in 1895 when biogas was recovered from a sewage treatment facility and used to fuel street lamps in Exeter. Advances in microbiology led to research by Buswell and others in the 1930s to identify anaerobic bacteria and the conditions that promote methane generation. From the 20 th century, anaerobic digestion technology has been identified as the most appropriate means of treating and processing agricultural wastes, especially in the area of animal production , where increased volume of manure and effluents poses an environmental hazard. Anaerobic digestion technology is being integrated into cogeneration (generation of heat and power) and trigeneration (genera-tion of heat, power and cold) systems. SIGNIFICANCE: The knowledge of evolutionary development of anaerobic digestion will change the mindset of some skeptics that the technology could contribute, significantly, to so-cio-economic development.

Design, Development and Performance Evaluation of an Anaerobic Plant

The need for safe and cost effective alternative energy source is a major challenge facing developing economies globally. This study explored the design, development and performance evaluation of a cost effective anaerobic plant using locally available materials. The digester was fabricated at Amalgamated Tin Mining of Nigeria workshop using locally available materials such as mild steel, galvanize and copper pipes. The digester was used to digest cow dung mixed with water in the ratio of 1/1 by weight for a retention period of 12 days. Fifty (50kg) of cow dung of white Fulani cows that fed on the open field grasses in some part of Northern Nigeria were collected. The qualitative analysis of the biogas produced showed that the biogas contained 85.331% methane, 0.014% air, 0.013% carbon mono oxide, 1.596% Nitrogen and 13.011% carbon dioxide.