The Effects of Process Control Strategies on Composting Rate and Odor Emission

Poor compost quality and odor emission are often significant problems in the composting industry. Composting process control can potentially help reduce both of these problems. In spite of the recent development of a number of process control strategies, very few direct comparisons have been made between these, particularly in terms of compost quality and odor emission. To help address this need, a series of experiments were conducted to evaluate the effects of several in-vessel process control strategies on organic matter conversion, nitrogen transformation and pH, and odor emission. The strategies focussed on aeration control. Fixed aeration, temperature feedback, oxygen feedback, and combined temperature/oxygen feedback algorithms were tested. A modified algorithm called linear temperature feedback was also developed and tested. Results showed that the compost temperature profiles were quite similar for the various feedback control algorithms, whereas fixed rate aeration led to significantly higher temperature, as expected. Compost properties such as C:N ratio and organic matter loss were also similar between process control methods. However, oxygen content was maintained more consistently using oxygen feedback or linear temperature feedback algorithms. Linear temperature feedback is preferable to oxygen feedback in that it does not require oxygen sensors to operate. Mass emission rates of odorous gas (methyl mercaptan and dimethyl sulfide) were typically found to increase with higher aeration rates, such as those used to limit temperature, though the gas concentration was lower. For maximum retention of nitrogen, adequate supply of readily biodegradable carbon in the feedstock is vital.     

Recent Developments in Microbiotesting and Early Millennium Prospects

Small-scale toxicity testing with microbiotests is a rapidly-expanding component of the field of aquatic toxicology which contributes diverse contamination assessment tools and approaches for a variety of environmental (liquid and solid) media. In this short review on microbiotesting, some of the recent developments conducted under the second St. Lawrence River Action Plan (1993–1998) at the St. Lawrence Centre (Environment Canada, Quebec Region, Montreal) are recalled. These include 1) employing the SOS Chromotest to determine the genotoxic status of major industrial effluents discharging to the St. Lawrence River and their potential impact on downstream biota, 2) developing an algal solid phase assay to predict the toxic potential of freshwater sediments, 3) developing a microplate-based cnidarian assay to screen for toxicity of chemicals and environmental samples, 4) developing an alternative assay to whole fish acute (sub)lethal toxicity testing with the help of rainbow trout primary hepatocytes, 5) developing a microplate-based phagocytosis assay to check for immunocompetence of feral bivalve shellfish and 6) conducting a major investigation to develop a cost-effective multitrophic bioanalytical battery to assess the (geno)toxicity of freshwater sediments. In addition, integrative tools with specific microbiotests were respectively constructed to determine the toxic potential of industrial effluents (PEEP: Potential Ecotoxic Effects Probe) and that of sediments (SED-TOX). Such examples illustrate the diversity of on-going endeavors in the field of small-scale toxicity testing internationally, as further corroborated by recent books entirely dedicated to the subject. It is undeniable that many important challenges still lie ahead for this field early into the third millennium and likely well beyond.     

Low Impact Development (LID) Practices: A Review on Recent Developments,Challenges and Prospects

Water, Air, & Soil Pollution - Biocrude oil generation from microalgae and cyanobacteria through hydrothermal liquefaction generates an aqueous by-product (post-hydrothermal liquefaction...     

Needed: Regional Inventories of Organic Residuals

? As waste management planners seek to divert increasing amounts of materials from the municipal and commercial streams, the value of regions conducting inventories of organic residuals that could be composted becomes apparent. Since 1960, various research studies have analyzed the potential for applying urban wastes on agricultural lands, either directly or after composting. Specific studies described in this report were conducted in New Jersey, Maine and the Omaha, Nebraska — Council Bluffs, Iowa region.     

Overview of Recent Growth Trends in European Forests

Natural environmental changes and human activities have altered forest growth for centuries. Recent long-term growth investigations indicate an increasing growth trend in European forests. The investigations are based on forest inventory, permanent plot and tree analysis data. The observed trends are species specific, locally varying and modified by remarkably large periodic growth variations. On a European scale, species and site specific quantitative information about the extent and spatial as well as temporal variation in growth acceleration is lacking. Future growth development may differ from past observations. A better understanding of changes in site conditions, their causes and consequences is needed to guide sustainable management of European forests.     

Global Mercury Pollution and the Role of Gold Mining: An Overview

As described by Jernelov and Ramel (1995), the Scientific Committee on Problems of the Environment (SCOPE) sponsored an investigation of Hg in ecosystems with special emphasis on tropical regions. In these regions small-scale gold mining activities have occupied about 10 million people worldwide who use Hg for extracting gold.     

Emission Inventories for SO2 and NOx in Developing Country Regions in 1995 with Projected Emissions for 2025 According to Two Scenarios

Water, Air, &; Soil Pollution - Top-down inventories of anthropogenic SO2 and NOx emissions were compiled for 1995 for developing country regions. Regional emission factors were used to generate...     

Arsenic Chemistry in Soils: An Overview of Thermodynamic Predictions and Field Observations

Published information, both theoretical and experimental, on As chemical behavior in soils is reviewed. Because of many emission sources, As is ubiquitous. Thermodynamic calculations revealed that As(V) species (HAsO ₄ ^2- >H₂AsO ₄ ^- at pH 7) are more abundant in soil solutions that are oxidized more than pe+pH>9. Arsenic is expected to be in As(III) form (HAsO ₂ ⁰ =H₃AsO ₃ ⁰ >AsO ₂ ^- =H₂AsO ₃ ^- at pH 7) in relatively anoxic soil solutions with pe+pH<7. Adsorption on soil colloids is an important As scavenging mechanism. The adsorption capacity and behavior of these colloids (clay, oxides or hydroxides surfaces of Al, Fe and Mn, calcium carbonates, and/or organic matter) are dependent on ever-changing factors, such as hydration, soil pH, specific adsorption, changes in cation coordination, isomorphous replacement, crystallinity, etc. Because of the altering tendencies of soil colloids properties, adsorption of As has become a complex, empirical, ambiguous, and often a self contradicting process in soils. In general, Fe oxides/hydroxides are the most commonly involved in the adsorption of As in both acidic and alkaline soils. The surfaces of Al oxides/hydroxides and clay may play a role in As adsorption, but only in acidic soils. The carbonate minerals are expected to adsorb As in calcareous soils. The role of Mn oxides and biogenic particles in the As adsorption in soils appears to be limited to acidic soils. Kinetically, As adsorption may reach over 90% completion in terms of hours. Precipitation of a solid phase is another mechanism of As removal from soil solutions. Thermodynamic calculations showed that in the acidic oxic and suboxic soils, Fe-arsenate (Fe₃(AsO₄)₄)₂) may control As solubility, whereas in the anoxic soils, sulfides of As(III) may control the concentrations of the dissolved As in soil solutions. In alkaline acidic oxic and suboxic soils, precipitation of both Fe- and Ca-arsenate may limit As concentrations in soil solutions. Field observations suggest that direct precipitation of discrete As solid phases may not occur, except in contaminated soils. Chemisorption of As oxyanions on soil colloid surfaces, especially those of Fe oxide/hydroxides and carbonates, is believed to a common mechanisms for As solid phase formation in soils. It is suggested that As oxyanions gradually concentrate on colloid surfaces to a level high enough to precipitate a discrete or mixed As solid phase. Arsenic volatilization is another As scavenging mechanism operating in soils. Many soil organisms are capable of converting arsenate and arsenite to several reduced forms, largely methylated arsines which are volatile. These organisms may generate different or similar biochemical products. Methylation and volatilization of As can be affected by several biotic (such as type of organisms, ability of organism for methylation, etc.) and abiotic factors (soil pH, temperature, redox conditions, methyl donor, presence of other ions, etc.) factors. Information on the rate of As biotransformations in soils is limited. In comparison to the biologically assisted volatilization, the chemical volatilization of As in soils is negligible.     

Studies on Atmospheric Pollution,Acid Rain and Emission Control for their Precursors in Chongqing,China

Chongqing City in China has suffered from serious air pollution and acid rain caused by low graded raw coal (sulfur=ca. 3≈5%, ash=ca. 30%) combustion. In this paper, the situation of atmospheric pollution and acid rain in Chongqing are discussed, the reduction efficiency for sulfur dioxide (SO₂) with the bio-briquetting of the raw coal that is one of countermeasures for emission control of air pollutants due to domestic consumes was determined. The research indicated that the frequency of acid rain was high, more than 50% at urban area, and its pH was low, about 4.5. Under our experimental conditions, the reducing efficiency of sulfur SO₂ emission from high sulfur coal-biomass briquette amounted to 87%. The field investigation indicated that SO₂ indoor concentrations in case of using bio-briquette dropped to 1/2≈1/3 of the raw coal.     

N Cycle, N Flow Trends in Japan, and Strategies for Reducing N2O Emission and NO3^- Pollution

To feed an increasing population, large amounts of chemical nitrogen fertilizer have been used to produce much of our food, feed and fiber thereby increasing nitrogen levels in soils, natural waters, crop residues, livestock wastes,and municipal and agricultural wastes, with national and international concern about its potential adverse effects on environmental quality and public health. To understand these phenomena and problems, first the nitrogen cycle and the environment are described. Then recent trends for nitrogen cycling through the food and feed system, N2O emissions from fertilized upland and paddy soils, and NO3^- pollution in ground water in Japan are reported. Finally, mitigation strategies in Japan for reducing N2O emission and NO3^- pollution are proposed, including nitrification inhibitors, controlled release fertilizers, utilization of plant species that could suppress nitrification, utilizing the toposequence, government policy, and appropriate agricultural practices. Of all the technologies presented, use of nitrification inhibitors and controlled release fertilizers are deemed the most important with further development of these aspects of technologies being expected. These practices, if employed worldwide, could help reduce the load, or environmental deterioration, on the Earth‘s biosphere.     

An Overview: Recycling Nutrients from Crop Residues For Space Applications

Without some form of regenerative life support system, long duration space habitation or travel will be limited severely by the prohibitive costs of resupplying air, water, and food from Earth. Components under consideration for inclusion in a regenerative life support system are based on either physicochemical or biological processes. Physicochemical systems would use filtration and elemental phase changes to convert waste materials into usable products, while biological systems would use higher plants and bioreactors to supply crew needs. Neither a purely biological nor strictly a physicochemical approach can supply all crew needs, thus, the best each approach can offer will be combined into a hybrid regenerative life support system. Researchers at Kennedy Space Center (KSC) Advanced Life Support Breadboard Project have taken the lead on bioregenerative aspects of space life support. The major focus has been on utilization of higher plants for production of food, oxygen, and clean water. However, a key to any regenerative life support system is recycling and recovery of resources (wastes). In keeping with the emphasis at KSC on bioregenerative systems and with the focus on plants, this paper focuses on research with biologically-based options for resource recovery from inedible crop residues.     

香根草在我国的应用及研究综述

该文综述了香根划在我国的应用和研究现状,概括了香根草在我国的应用地域（华东,华南,西南等省区）及其应用,研究领域的演化,由香精提取→水土保持→泥沙和污染控制,饲料,食用菌培育及土工工程防护等应用研究多元化,总结了香根草在恶劣环境条件下起着先锋植物作用,能把太阳能充分转换为生物能和有机物质,为人类利用的同时也使得环境逐步改善,因此具有极大的应用潜力和研究价值。     

An Overview of Nitrogen Critical Loads for Policy Makers, Stakeholders, and Industries in the United States

Critical load values are calculated to determine ecosystem responses to deposition in a given area; these values may act as a tool to identify sensitive ecosystems in further need of protection. This overview provides an introduction to nitrogen critical loads for policy makers and parties involved in managing nitrogen deposition including electric utility generators, transportation managers and automobile manufacturers, and large-scale agricultural operators in the United States. It examines the use of the critical loads concept in European nations for establishing policy guidelines, current research on nitrogen critical loads in the U.S., and the development of nitrogen critical loads modeling and mapping.     

土壤中木质素的研究进展

木质素是地球上最丰富的芳香族化合物,是土壤中非常稳定的有机组分,也是影响土壤有机碳循环的重要物质,因此,研究木质素在农田土壤中的积累对于土壤碳素的循环过程以及土壤有机碳的截获具有十分重要的意义。本文对土壤中木质素的分类和来源、测定及表征方法进行了综合介绍,并着重评述了木质素对于土壤有机碳循环的贡献、在土壤中的保持机制及影响木质素在土壤中降解和积累特性的因素,以期为我国开展土壤木质素的相关研究提供理论参考。     

Emission Control of SO2 by Dry Coal-Cleaning and Bio-Briquette Technology

In China, the large amount of sulfur dioxide and dust discharged from the combustion of low-grade raw coal causes severe air pollution and acid rain. Therefore, the need to control the emission of such pollutants is urgent. It is well known that wet coal-cleaning technology is used to prepare clean coal from low-grade raw coal containing large amounts of sulfur and ash. However, this technology is not used in areas where water is scarce or severely polluted, because of the high cost of treating the wastewater. In an attempt to overcome this limitation, we studied an integrated technology, which combines dry coal-cleaning and bio-briquetting technologies, to prepare clean coal from low-grade raw coal. In the dry coal-cleaning method, refined coal was separated from ash and other minerals containing inorganic sulfur as pyrite by means of the differences in their electrostatic character. Most of the sulfur left in the refined coal was organic sulfur. The residual ash was fixed in combustion ashes of bio-briquettes made from coal, biomass, and slaked lime (Ca/S mole ratio =2) under pressure. By combining these two technologies, we were able to decrease the emission of sulfur dioxide and ash by 70≈90% compared to the combustion of raw coal.     

Use of Spent Mushroom Substrate for Growing Containerized Woody Ornamentals: An Overview

There are substantial environmental and economic benefits to be gained by recycling spent mushroom substrate (SMS). Researchers throughout the world have grown many types of crops with SMS but information with ornamental nursery crops is sparse. High salt levels in SMS is largely responsible for its restricted use in agriculture. Investigations showed that many ornamental woody species grew well in 6-liter (2-gal) regular nursery containers amended with different proportions of SMS (33%, 67%, and 100% by volume) mixed with bark. Test species were: cotoneaster (Cotoneaster dammeri ‘Coral Beauty’); deutzia (Deutzia gracilis); dogwood (Cornus alba and C. alba ‘Argenteo-marginata’); forsythia (Forsythia × intermedia ‘Lynwood’); juniper (Juniperus sabina ‘Blue Danube’ and J. virginiana ‘Hetzii’); ninebark (Physocarpus opulifolius); potentilla (Potentilla fructicosa ‘Red Ace’); privet (Ligustrum vulgare); rose (Rosa ‘John Franklin’); and weigela (Weigela ‘Bristol Ruby’ and W. florida ‘Variegata Nana’). Despite variable species response, there was little relationship of growth performance to: source of SMS (different farms, fresh or aged, leached or unleached); initial or subsequent salt levels in the media; chemical or physical characteristics of the media, including increasing shrinkage with increasing amounts of SMS; or contents of leaf nutrients. Plants of all species, except privet, achieved marketable size and quality at harvest. Time-course studies demonstrated that rapid leaching of undesirable high salt levels from the containers was the key to our successful results. In further studies which evaluated a wider range of amendment combinations (peat, bark, and sand) with SMS included in amounts (25% or 50%) more desirable in commercial container nursery practice, all SMS amended media promoted excellent growth of nursery crops. Minimal shrinkage was obtained with a medium consisting of 25% sand, 25% SMS, and 50% peat or bark.     

欧洲受损生态系统恢复与重建研究进展

自20世纪70年代以来,受损生态系统的恢复与重建研究大量涌现。生态系统退化成为世界各国普遍面临的重要问题,并成为当前各国重视的焦点和生态学研究的热点之一。欧洲大部分地区都有很长的人类定居史,景观已经高度改变。在大量文献调研的基础上,从欧洲的生态系统类型出发,对欧洲生态恢复与重建研究作了总结,包括生态环境退化的现状,生态恢复的限制条件,生态与社会经济方面的限制和科学上的不确定性等．并对欧洲各国在森林、河流、湖泊、湿地、废弃地等生态系统类型典型生态恢复与重建的实践案例进行了分析。总结了欧洲生态恢复的促进因素,包括欧盟的作用,重要协议的颁布执行．生态网络的发展,公共参与的影响,财政援助等方面。最后对欧洲生态恢复与重建存在的问题和发展趋势及其对中国的借鉴作用进行了论述。