Technological options for the management of biosolids

BACKGROUND, AIM, AND SCOPE: Large quantities of biosolids (sewage sludge), which are produced from municipal wastewater treatment, are ever-increasing because of the commissioning of new treatment plants and continuous upgrades of the existing facilities. A large proportion of biosolids are currently landfilled. With increasing pressure from regulators and the general public, landfilling of biosolids is being phased out in many countries because of potential secondary pollution caused by leachate and the emission of methane, a potent greenhouse gas. Biosolids contain nutrients and energy that can be used beneficially. Significant efforts have been made recently to develop new technologies to manage biosolids and make useful products from them. In this paper, we provide a review of the technologies in biosolids management. MATERIALS AND METHODS: A survey of literature was conducted. RESULTS: At present, the most common beneficial use of biosolids is agricultural land application because of inherent fertilizer values found in biosolids. Expansion of land application, however, may be limited in the future because of more stringent regulatory requirements and public concern about food chain contamination in some countries. Perceived as a green energy source, the combustion of biosolids has received renewed interest. Anaerobic digestion is generally a more effective method than incineration for energy recovery, and digested biosolids are suitable for further beneficial use through land application. Although conventional incineration systems for biosolid management generally consume more energy than they produce because of the high moisture content in the biosolids, it is expected that more combustion systems, either monocombustion or cocombustion, will be built to cope with the increasing quantity of biosolids. DISCUSSION: Under the increasingly popular low-carbon economy policy, biosolids may be recognized as a renewable fuel and be eligible for 'carbon credits'. Because ash can be used to manufacture construction materials, combustion can provide a complete management for biosolids. A number of advanced thermal conversion technologies (e.g., supercritical water oxidation process and pyrolysis) are under development for biosolids management with a goal to generate useful products, such as higher quality fuels and recovery of phosphorus. With an ever-increasing demand for renewable energy, growing bioenergy crops and forests using biosolids as a fertilizer and soil amendment can not only contribute to the low-carbon economy but also maximize the nutrient and carbon value of the biosolids. CONCLUSIONS: Land application of biosolids achieves a complete reuse of its nutrients and organic carbon at a relatively low cost. Therefore, land application should become a preferred management option where there is available land, the quality of biosolids meet regulatory requirements, and it is socially acceptable. Intensive energy cropping and forest production using biosolids can help us meet the ever-increasing demand for renewable energy, which can eliminate the contamination potential for food sources, a common social concern about land application of biosolids. In recent years, increasing numbers of national and local governments have adopted more stringent regulations toward biosolid management. Under such a political climate, biosolids producers will have to develop multireuse strategies for biosolids to avoid being caught because a single route management practice might be under pressure at a short notice. Conventional incineration systems for biosolids management generally consume more energy than they produce and, although by-products may be used in manufacturing, this process cannot be regarded as a beneficial use of biosolids. However, biosolids are likely to become a source of renewable energy and produce 'carbon credits' under the increasingly popular, low-carbon economy policy. RECOMMENDATIONS AND PERSPECTIVES: To manage biosolids in a sustainable manner, there is a need for further research in the following areas: achieving a higher degree of public understanding and acceptance for the beneficial use of biosolids, developing cost-efficient and effective thermal conversions for direct energy recovery from biosolids, advancing technology for phosphorus recovery, and selecting or breeding crops for efficient biofuel production.     

Adapting the bioblitz to meet conservation needs

When conservation strategies require new, field‐based information, practitioners must find the best ways to rapidly deliver high‐quality survey data. To address this challenge, several rapid‐assessment approaches have been developed since the early 1990s. These typically involve large areas, take many months to complete, and are not appropriate when conservation‐relevant survey data are urgently needed for a specific locale. In contrast, bioblitzes are designed for quick collection of site‐specific survey data. Although bioblitzes are commonly used to achieve educational or public‐engagement goals, conservation practitioners are increasingly using a modified bioblitz approach to generate conservation‐relevant data while simultaneously enhancing research capacity and building working partnerships focused on conservation concerns. We term these modified events expert bioblitzes. Several expert bioblitzes have taken place on lands of conservation concern in Southern California and have involved collaborative efforts of government agencies, nonprofit organizations, botanic gardens, museums, and universities. The results of expert bioblitzes directly informed on‐the‐ground conservation and decision‐making; increased capacity for rapid deployment of expert bioblitzes in the future; and fostered collaboration and communication among taxonomically and institutionally diverse experts. As research and conservation funding becomes increasingly scarce, expert bioblitzes can play an increasingly important role in biodiversity conservation.     

Comanagement of wildlife corridors: the case for citizen participation in the Algonquin to Adirondack proposal

The debate between top-down and bottom-up planning has recently re-emerged in environmental management. Many commentators agree on the merits of comanagement, in which affected citizens and professional managers share responsibility for planning. Nevertheless, the manifold advantages of comanagement have not always been fully appreciated in environmental planning. For example, a group representing NGOs and academic institutions recently proposed an ecological corridor linking Algonquin Provincial Park in southern Ontario to the Adirondack Park in northern New York. This corridor, known as A2A, was designed to encourage the migration of wolves and other wildlife between the parks. Much of the land in A2A is private property. A survey of households, randomly scattered throughout the United States portion of the corridor, revealed that affected landowners had little knowledge of the proposal and no contact with its advocates. Many respondents were farmers who utilized land for livelihood. Other landowners enjoyed property for a variety of recreational purposes. Regardless of use, survey participants placed high value on the importance of conserving biological diversity. They also expressed great distrust toward restrictions that might be placed on their activities. In general, respondents felt very unsure about A2A, and they were uncertain about personal involvement in the planning process. Certain landowners indicated a willingness to have their land be included in an ecological corridor, despite not knowing about it before the survey was administered. These results suggest that A2A proponents have little to lose and much to gain by disseminating information locally and by embracing comanagement for further formulation of this plan.     

Mainstreaming environmental sustainability into South Africa's integrated development planning process

The advent of democracy in South Africa in 1994 has resulted in a radical law reform process, new systems of governance, and significantly transformed planning and decision-making processes. At the same time, principles of sustainability, integration, participation, social and environmental justice have also been placed squarely on the South African political agenda. Local government has become the intended focal point for addressing the socio-economic needs of local communities and sustainable service delivery, with the principal tool for achieving these developmental objectives the Integrated Development Plan (IDP). This paper examines the available policy frameworks, including those at the national level, guiding incorporation of environmental sustainability considerations into IDPs and highlights difficulties of achieving this in practice. Ideas for moving beyond rhetoric to practical mainstreaming of environmental sustainability considerations in IDPs are provided.     

Elemental distribution in relation to skin necroses of marine flatfishes from the english channel

It has been suggested that industrial waste discharges are associated with the occurrence of fin damage and skin lesions. A mixed population of diseased and healthy blatfish consisting ofLimanda limanda, Pleuronectes platessa, Platichthys flesus andSolea solea were collected from an industrialised area (Calais, France) and were compared with diseased and healthyl. limanda caught in a non-industrialised area (Brixham, England). Analysis of skin samples from necrosed and healthy fish by X-ray microanalysis and atomic absorption spectroscopy has shown that no elemental accumulation occurs either in necrosed fish, or fish from an industrialised area. The fish from Calais were heavily infested with the ectoparasitic copepodLepeophtheirus pectoralis (O.F. Müller) and, although few were found on fish from Brixham, it is unlikely that this infestation was related to the discharge of industrial effluents.     

The effect of Kuwait crude oil and a solvent emulsifier on the metabolism of the marine lichen Lichina pygmaea

As lichens are sensitive monitors of environmental pollution and are known to be affected by marine pollutants, a study was made of the effect of Kuwait crude oil and a solvent emulsifier (BP 1002) on the metabolism of the marine lichen Lichina pygmaea (Lightf.) C. Ag. Photosynthesis in the presence of NaH¹⁴CO₃ enabled an investigation to be made of the effect of these pollutants on the total ¹⁴C-fixation and the pattern of ¹⁴C-fixation. Oil was shown to be substantially less inhibitory than the emulsifier to the total ¹⁴C fixed. The emulsifier, but not the oil, induced loss of labelled material from the lichen. No change was observed in the influence of oil or undiluted emulsifier after ageing. Combination of the emulsifier with either oil or sea water resulted in a decreased inhibitory effect, which was further reduced on ageing the mixture. It was concluded that the inhibitory component of the emulsifier was the surfactant and not the solvent.     

In situ soil treatments to reduce the phyto- and bioavailability of lead, zinc, and cadmium

A study was established near a former Zn and Pb smelter to test the ability of soil amendments to reduce the availability of Pb, Zn, and Cd in situ. Soil collected from the field was amended in the lab with P added as 1% P-H3PO4, biosolids compost added at 10% (referred to hereafter as "compost"), and a high-Fe by-product (referred to hereafter as "Fe") + P-triple superphosphate (TSP) (2.5% Fe + 1% P-TSP) and incubated under laboratory conditions at a constant soil pH. Changes in Pb bioavailability were measured with an in vitro test and a feeding study with weanling rats. Field-amended and incubated soils using these plus additional treatments were evaluated using the in vitro extraction and tall fescue (Festuca arundinacea Schreb. cv. Kentucky-31) metal concentration. Reductions were observed across all parameters but were not consistent. In the feeding study, the 1% P-H3PO4 and compost treatments resulted in a decrease of 26% in rat tissue Pb concentration compared with the control soil. The 2.5% Fe + 1% P-TSP showed a 39% decrease. The 1% P-H3PO4 treatment caused the greatest reduction in in vitro extractable Pb from field samples (pH 2.2) with a measured reduction of 66%, while the compost treatment had a 39% reduction and the 2.5% Fe + 1% P-TSP treatment a 50% reduction. The in vitro extraction (pH 1.5) run on field samples showed no reduction in the compost or Fe treatments. The 1% P-H3PO4 treatment was the most effective at reducing plant Pb, Zn, and Cd.