Fate of pathogen indicators in a domestic blend of food waste and wastewater through a two-stage anaerobic digestion system

Anaerobic digestion is a viable on-site treatment technology for rich organic waste streams such as food waste and blackwater. In contrast to large-scale municipal wastewater treatment plants which are typically located away from the community, the effluent from any type of on-site system is a potential pathogenic hazard because of the intimacy of the system to the community. The native concentrations of the pathogen indicators Escherichia coli, Clostridium perfringens and somatic coliphage were tracked for 30 days under stable operation (organic loading rate (OLR) = 1.8 kgCOD m(-3) day(-1), methane yield = 52% on a chemical oxygen demand (COD) basis) of a two-stage laboratory-scale digester treating a mixture of food waste and blackwater. E. coli numbers were reduced by a factor of 10(6.4) in the thermophilic stage, from 10(7.5+/-0.3) to 10(1.1+/-0.1) cfu 100 mL(-1), but regenerated by a factor of 10(4) in the mesophilic stage. Neither the thermophilic nor mesophilic stages had any significant impact on C. perfringens concentrations. Coliphage concentrations were reduced by a factor of 10(1.4) across the two stages. The study shows that anaerobic digestion only reduces pathogen counts marginally but that counts in effluent samples could be readily reduced to below detection limits by filtration through a 0.22 microm membrane, to investigate membrane filtration as a possible sanitation technique.

Abstract proceedings : Second Forum on Innovative Hazardous Waste Treatment Technologies, Domestic and International : Philadelphia, PA, May 15-17, 1990.

Mode of access: Internet.

Second Forum on Innovative Hazardous Waste Treatment Technologies, Domestic and International : Philadelphia, Pennsylvania, May 15-17, 1990 : technical papers.

Mode of access: Internet.

Technical papers : Third Forum on Innovative Hazardous Waste Treatment Technologies, Domestic and International : Dallas, TX, June 11-13, 1991.

Mode of access: Internet.

Abstract proceedings : Fourth Forum on Innovative Hazardous Waste Treatment Technologies, Domestic and International : San Francisco, CA, November 17-19, 1992.

Mode of access: Internet.

Colour coding the fridge to reduce food waste

This paper introduces the first iteration of a study aimed at grouping similar food types together in a refrigerator to increase the awareness of available foods for consumers in a domestic environment. The goals of the project are twofold: i) Raise the awareness of available foods for all members of a household; ii) Reduce the amount of expired food waste in the household. The project implemented a paper-based colour scheme in refrigerators in households, assigning colours to particular food types (e.g. green to fruit and vegetables, red to meat, etc.). The findings show that the colour coding raised participants’ awareness of available food items in the fridge, particularly for those participants who were not directly involved in the shopping and initial storage of each food item. The findings also indicate that such awareness led to a reduction in expiration of food and thus general food waste in the household. These preliminary findings suggest that raising awareness of food availability through categorisation and efficient communication of this information may lead to a reduction in food waste in domestic environments.

EatChaFood : challenging technology design to slice food waste production

This paper presents work in progress of EatChaFood – a prototype app designed to increase user knowledge of the currently available domestic supply and location of food, with a view to reducing expired household food waste. In order to reap the benefits that EatChaFood can provide we explore ways to overcome manual data entry as a barrier to use. Our user study has to recognise the limitations of the prototype app, and conduct an evaluation of the interaction design built into the app to promote behaviour change. Innovations in the near future such as the automatic scanning of barcodes on food items or photo-recognition will close the gap between perceived prototype usability and usefulness.

Food talks back : Exploring the role of mobile applications in reducing domestic food wastage

Mitigating domestic food waste reduces its environmental and economic impacts. In our study, we have identified the use of mobile technology to support behaviour change as a key tool to assist the process of reducing food waste. This paper reports on three mobile applications designed to reduce domestic food waste: Fridge Pal, LeftoverSwap and EatChaFood. The paper examines how each app can influence consumer knowledge of domestic food supply, location, and literacy. We discuss our findings with respect to three considerations: (i) assisting with the user’s food supply and location knowledge; (ii) improving the user’s food literacy; (iii) facilitating social food sharing of excess food. We present new insights for mobile interventions that encourage changes towards more sustainable behaviours to reduce food waste.

Technicolouring the fridge : reducing food waste through uses of colour-coding and cameras

Domestic food wastage is a growing problem for the environment and food security. Some causes of domestic food wastes are attributed to a consumer’s behaviours during food purchasing, storage and consumption, such as: excessive food purchases and stockpiling in storage. Recent efforts in human-computer interaction research have examined ways of influencing consumer behaviour. The outcomes have led to a number of interventions that assist users with performing everyday tasks. The Internet Fridge is an example of such an intervention. However, new pioneering technologies frequently confront barriers that restrict their future impact in the market place, which has prompted investigations into the effectiveness of behaviour changing interventions used to encourage more sustainable practices. In this paper, we investigate and compare the effectiveness of two interventions that encourage behaviour change: FridgeCam and the Colour Code Project. We use FridgeCam to examine how improving a consumer’s food supply knowledge can reduce food stockpiling. We use the Colour Code Project to examine how improving consumer awareness of food location can encourage consumption of forgotten foods. We explore opportunities to integrate these interventions into commercially available technologies, such as the Internet Fridge, to: (i) increase the technology’s benefit and value to users, and (ii) promote reduced domestic food wastage. We conclude that interventions improving consumer food supply and location knowledge can promote behaviours that reduce domestic food waste over a longer term. The implications of this research present new opportunities for existing and future technologies to play a key role in reducing domestic food waste.

Management of Municipal Solid Waste

Solid material thrown away as unused from various sectors such as agricultural, commercial, domestic, industrial and institutional constitutes solid wastes. This places an enormous strain on natural resources and seriously undermines efficient and sustainable development. Management of Municipal Solid Waste discusses the ways to salvage the situation through efficient management of solid wastes from waste generation to final disposal. The various processes such as waste generation, collection, storage, processing, recovery, transport, and disposal, are explained with the support of case studies. The book discusses reduction of waste at the source and to foster implementation of integrated solid waste management systems that are cost-effective and protect human health and the environment.

Application of algal bioassays in the determination of eutrophic power of waste water (”Conclusions” only) [Translation from: 1g.Sanita pubbl. 31 257-267, 1975]

The best evidence for establishing the level of eutrophy of a water-body is its algal production which makes it possible to identify the type and the intensity of the eutrophication according to the kind and number of algal species present: when the number of algae exceeds half a million per litre then one speaks o an ”algal bloom”. The scope of the present research aims to verify if the alga Selenastrum capricornutum can be used as a test alga under our culture conditions and to determine the eutrophic level of the secondary effluent of a modern plant for the treatment of domestic discharge and to investigate the eventual ”limiting factors”. Finally this paper aims to study the effect on the secondary effluent of tertiary treatment carried out artificially in the laboratory.

Biomethane production from food waste and organic residues

Anaerobic digestion (AD) of biodegradable waste is an environmentally and economically sustainable solution which incorporates waste treatment and energy recovery. The organic fraction of municipal solid waste (OFMSW), which comprises mostly of food waste, is highly degradable under anaerobic conditions. Biogas produced from OFMSW, when upgraded to biomethane, is recognised as one of the most sustainable renewable biofuels and can also be one of the cheapest sources of biomethane if a gate fee is associated with the substrate. OFMSW is a complex and heterogeneous material which may have widely different characteristics depending on the source of origin and collection system used. The research presented in this thesis investigates the potential energy resource from a wide range of organic waste streams through field and laboratory research on real world samples. OFMSW samples collected from a range of sources generated methane yields ranging from 75 to 160 m3 per tonne. Higher methane yields are associated with source segregated food waste from commercial catering premises as opposed to domestic sources. The inclusion of garden waste reduces the specific methane yield from household organic waste. In continuous AD trials it was found that a conventional continuously stirred tank reactor (CSTR) gave the highest specific methane yields at a moderate organic loading rate of 2 kg volatile solids (VS) m-3 digester day-1 and a hydraulic retention time of 30 days. The average specific methane yield obtained at this loading rate in continuous digestion was 560 ± 29 L CH4 kg-1 VS which exceeded the biomethane potential test result by 5%. The low carbon to nitrogen ratio (C: N <14:1) associated with canteen food waste lead to increasing concentrations of volatile fatty acids in line with high concentrations of ammonia nitrogen at higher organic loading rates. At an organic loading rate of 4 kg VS m-3day-1 the specific methane yield dropped considerably (381 L CH4 kg-1 VS), the pH rose to 8.1 and free ammonia (NH3 ) concentrations reached toxicity levels towards the end of the trial (ca. 950 mg L-1). A novel two phase AD reactor configuration consisting of a series of sequentially fed leach bed reactors connected to an upflow anaerobic sludge blanket (UASB) demonstrated a high rate of organic matter decay but resulted in lower specific methane yields (384 L CH4 kg-1 VS) than the conventional CSTR system.

Widespread supplementary feeding in domestic gardens explains the return of reintroduced Red Kites Milvus milvus to an urban area

Reintroductions are used worldwide to mitigate biodiversity loss. One prominent case is a charismatic raptor of conservation concern, the Red Kite Milvus milvus. This species has been reintroduced across the UK over the last 25 years following its near extinction after centuries of persecution. The species was not expected to recolonize urban areas; its historical association with human settlements is attributed to scavenging on human waste and refuse, a resource now greatly reduced on the streets of modern Western cities. However, the species has become a common day-time visitor to a large conurbation centred on the town of Reading, southern England, approximately 20 km from the first English reintroduction site. Given a near-absence of breeding and roost sites, we investigated foraging opportunities and habitat associations that might explain use by Red Kites of this urban area. Surveys of discarded human foods and road-kill suggested that these could support at most 13−29 kites/day. Face-to-face surveys of a cross-section of residents revealed that 4.5% (equivalent to 4349 households) provided supplementary food for kites. Using estimates of per-household resource provision from another study, we calculated that this level is potentially sufficient to provision 142−320 kites, a substantial proportion of the total estimated to visit the conurbation each day (between 140 and 440). Road transects found positive associations between Red Kites and residential areas. We therefore suggest that the decision made by thousands of individuals to provide supplementary food for Red Kites is the primary factor explaining their day-time abundance in this urban area.

Potential of municipal solid waste (MSW) as a source of energy in São Paulo: Its impact on CO2 balance

Energy generation is needed in São Paulo and MSW represents a promising alternative, although it is more expensive than hydroelectric power. About 14 900 t/day of MSW is generated, of which 8433 t/day is domestic and commercial MSW. From this amount, 1800 t will be destined to generate 30 MW of power. The eco-balance of CO2 has been considered for incineration and recycling. The recycling program of plastics, metals, paper and glass would represent a significant reduction in energy and CO2 emission. The total CO2 released is 3.34 x 10(5) t/yr without recycling. and is 1.25 x 10(5) t/yr with a recycling program. Most of the CO2 comes from plastics and paper production. Economic aspects could probably favor Incineration with energy production as the best option. (C) 1998 Published by Elsevier B.V. Ltd. All rights reserved.

Relationship between age of waste and natural electric potential generation in Sanitary Landfill

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)