The transformations of organic nitrogen to ammonium and nitrate are central processes in the internal soil nitrogen cycle. In most agricultural soils, ammonium is rapidly oxidized to nitrate in the process known as nitrification; often leading to loss of nitrate from the system. Nitrification is mediated by ammonia oxidizing bacteria or archaea, and nitrite oxidizing bacteria. Understanding links between process rates, enzyme activities and the communities of microbes that cycle nitrogen may contribute to sustainable management. Our main objective was to determine the impacts of contrasting nitrogen management on soil microbial communities, enzyme activities, and functional genes for nitrification and nitrogen mineralization in a Utah agricultural system. Process rates and activities were measured in laboratory potential assays and 15N isotope pool dilution experiments. The abundance and diversity of genes involved in nitrification and nitrogen mineralization were examined using quantitative real-time PCR, pyrosequencing, clone libraries, and metagenomics. Key enzymes and their relevant marker genes included ammonia monooxygenase (amoA), nitrite oxidoreductase (nxrB), protease (npr and sub), chitinase (chiA), and urease (ureC). The overall soil microbial community composition was assessed targeting ribosomal genes. Ammonia oxidizing bacteria were more responsive than archaea to ammonium fertilizers while the archaea were competitive under low ammonium levels. The relative contribution of ammonia oxidizing archaea to nitrification increased with increasing temperature and their activity had a higher temperature optimum than bacteria. The abundance of ammonia oxidizers in the organic farming system increased with organic nitrogen fertilizers and their activity was higher in manure than in compost treated soil. Nitrogen fertilizers strongly stimulated the rates of potential nitrite oxidation. Nitrospira was the only known nitrite oxidizer genus recovered from any soil sample. The application of organic nitrogen fertilizers, but not inorganic, increased the diversity of the prokaryotic community and the activities of soil enzymes. In the organic farming system, abundances of functional genes for mineralization were increased by organic nitrogen fertilizer and these abundances were significantly correlated with corresponding enzyme activity. Understanding the link between microbial communities and the biogeochemical functions of nitrification and mineralization may allow ecosystem models to incorporate microorganisms as dynamic components driving nitrogen flux.

<p>The Hull Street Integrated Housing Project, in Kimberley, is one of the projects supported by the Swedish International Development Cooperation Agency, Sida, in South Africa. The vision of the</p><p>project is to provide low cost housing for the people of Kimberley. As a way of ensuring sustainability, the project adopts the Ecological sanitation (Ecosan) approach where urine and</p><p>faeces are separated from the source.</p><p>The concept of Ecosan is new to many people around the world. To make the concept workable and acceptable effective implementation strategies are required.</p><p>At the Hull Street, after the first of the four phases 144 unit houses have been completed all fitted</p><p>with the UDS. Urine from the UDS as well as the greywater from the kitchen and bathroom are connected to infiltrate into the ground. This arrangement is called the “quick-fix”. The faeces from</p><p>the houses are sent to the compost yard for composting so that the residents could use the compost in their gardens.</p><p>This study which involves interview with some selected workers and residents in Hull Street</p><p>focuses on the modus operandi of the Ecosan unit of the Hull Street project with special emphasis on the methods of human excreta disposal and education strategies.</p>

Urban development will continue to increase in Texas because of population growth and urban sprawl. Despite the desire for urbanization and expansion of the economy, this growth increases the amount of construction, which, if not properly managed, can increase non-point source pollution and threaten surface water quality. Therefore, Texas Department of Transportation (TxDOT) has approved and promoted the use of compost as a stormwater best management practice (BMP) during highway construction. The objectives of this study were to construct and calibrate an indoor rainfall simulator and to determine the effectiveness of using compost rather than conventional hydroseeding or topsoil to reduce erosion from disturbed soils. Runoff rates, interrill erosion, and interrill erodibility were determined and compared across five compost treatments following TxDOT specifications for compost applied as an erosion control and two control treatments of topsoil (TS) and hydroseeding (HS) applied at 5 cm depth. The simulator produced 89% uniformity using ten Veejet 80100 nozzles at a target rate of 100 mm h-1. The surface runoff was collected after 5 minutes of rainfall (first flush) and during the last 30 minutes of rainfall (steady-state). The first flush mean runoff for GUC-5 treatment was significantly higher than all other treatments. All other treatments; 50% woodchips and 50% compost blend (ECC-1.3, ECC-5), and hydroseeding (HS) had significantly lower runoff and erosion rates compared to topsoil (TS) and compost manufactured topsoil (CMT) at first flush and steady-state. Furthermore, there were no performance differences between 1.3 cm and 5 cm compost applications at first flush or steady-state. The results of this project indicate that particle size, soil moisture capabilities, and time at which rainfall is applied affect surface runoff. TxDOT specification of using ECC at 5 cm depth on a max of 3:1 slope should be reconsidered. An ECC application depth of 1.3 cm was effective in reducing first flush runoff and interrill erosion rates.

During the last years, the implementation of new Wastewater Treatment Plants has lead to a significant increase of sludge production. As a response, sludge valorisation in agriculture is the preferred option nowadays, ensuring the return of organic constituents, nutrients and microelements to crop fields. In practice, sludge treatments should provide a final product suitable for land application, with reasonable investment as well as operational and maintenance costs. In this sense, sludge treatment wetlands (STW) appear as a suitable technology for sludge management from an economic and environmental point of view. The main objective of this research work was to assess the suitability of STW for sludge management; with special focus on small communities of the Mediterranean Region. To this end, technical, environmental and economic aspects of the treatment were studied in 3 full-scale systems and in a pilot plant located in Catalonia. A comparison with conventional treatments for sludge management is presented in order to establish the most favourable solution for the Catalan context. As the final result from this work, design and operation criteria are proposed as a guide for STW implementation in small Mediterranean communities. The study of the performance of the full-scale STW suggests good treatment efficiency. Moisture content was reduced by 16-30%, reaching efficiencies similar to those of conventional dewatering technologies. On the other hand, VS were reduced up to 30-49%VS/TS, suggesting the progressive sludge stabilisation and mineralisation. Similar values were found at the end of the treatment in the pilot plant. In this case the sludge volume was reduced around 80% and TS increased up to 16-24%. However, the observed VS reduction (up to 50%VS/TS) after 2 months without feeding, indicates that longer resting periods should be applied in order to increase mineralisation of the sludge. A finite element model able to simulate sludge dewatering in STW was developed by combining the evapotranspiration (ET) and the Terzaghi¿s consolidation theory representing water percolation. The model allows for the determination of the most appropriate feeding frequency as a function of the sludge height stored on the wetland. Similarly, the sludge loading rate is determined as a function of ET, feeding frequency and sludge height. On the whole, the model implemented is a useful tool for the establishment of standardised criteria of STW operation. The characterisation of the final product from the pilot plant and from three full-scale systems demonstrated the suitability of biosolids as organic fertilisers. DRI values indicated the partial stabilisation of the product. Moreover, the absence of phytotoxicity and the heavy metals concentrations below the legal thresholds confirmed their viability to be reused in agriculture. However, in the pilot plant, pathogens were still present after 2 resting months, confirming the necessity of a longer resting period. Monitoring the stabilisation degree as phytotoxicity, heavy metals and pathogens' concentration during the final resting period would help optimising its duration. Looking at the environmental aspects, the static chamber method was successfully adapted to the determination of gas emissions from STW. Aerobic conditions before sludge feeding, characterised by low methane emissions and high nitrous oxide emissions, were strongly altered by fresh sludge feeding, which increases CH4 emissions and reduces N2O emissions. According to the measured emissions, the Global warming potential of STW corresponds to 17kgCO2eq/PE¿y, which is from 2 to 9 times lower than that of sludge centrifugation and transport. Besides,the economic and environmental assessment indicates STW with direct land application as the most cost-effective technique, which is also characterised by the lowest environmental impact.Thus STW are the best solution to manage waste sludge in decentralised small communities.

This study aimed at seeking for the solution to recover the energy from agriculture waste in the Mekong Delta, Vietnam. The spent mushroom compost - a residue from the mushroom growing - was chosen for co-digestion with pig manure in anaerobic batch and semi-continuous experiments. The results showed that in case of spent mushroom compost made up 75% of the mixed substrate, the gained biogas volume was not significantly different compared to the treatment fed solely with 100% pig manure. The average produced biogas was 4.1 L×day-1 in the experimental conditions. The semi-continuous experiments remained in good operation up to the 90th day of the fermentation without any special agitating method application. The methane contents in both experiments were around 60%, which was significantly suitable for energy purposes. These results confirm that spent mushroom compost is possibly an acceptable material for energy recovery in the anaerobic fermentation process. / Nghiên cứu này nhằm tìm kiếm giải pháp thu hồi năng lượng từ chất thải nông nghiệp tại ĐBSCL, Việt Nam. Rơm sau ủ nấm - phế phẩm sau khi trồng nấm rơm - được chọn để ủ kết hợp với phân heo trong các bộ ủ yếm khí theo mẻ và bán liên tục. Kết quả cho thấy nếu phối trộn đến 75% rơm sau ủ nấm trong nguyên liệu ủ, tổng lượng khí thu được không khác biệt đáng kể so với thí nghiệm ủ 100% phân heo. Trong điều kiện thí nghiệm, lượng khí thu được trung bình là 4.1 L.ngày-1. Thí nghiệm ủ bán liên tục vẫn vận hành tốt ở ngày thứ 90 mặc dù mẻ ủ không được khuấy đảo. Hàm lượng khí mê-tan đo được chiếm khoảng 60% hoàn toàn có thể sử dụng cho các nhu cầu về năng lượng. Những kết quả thí nghiệm khẳng định có thể sử dụng rơm sau ủ nấm để thu hồi năng lượng thông qua quá trình ủ yếm khí kết hợp.

Urban development will continue to increase in Texas because of population growth and urban sprawl. Despite the desire for urbanization and expansion of the economy, this growth increases the amount of construction, which, if not properly managed, can increase non-point source pollution and threaten surface water quality. Therefore, Texas Department of Transportation (TxDOT) has approved and promoted the use of compost as a stormwater best management practice (BMP) during highway construction. The objectives of this study were to construct and calibrate an indoor rainfall simulator and to determine the effectiveness of using compost rather than conventional hydroseeding or topsoil to reduce erosion from disturbed soils. Runoff rates, interrill erosion, and interrill erodibility were determined and compared across five compost treatments following TxDOT specifications for compost applied as an erosion control and two control treatments of topsoil (TS) and hydroseeding (HS) applied at 5 cm depth. The simulator produced 89% uniformity using ten Veejet 80100 nozzles at a target rate of 100 mm h-1. The surface runoff was collected after 5 minutes of rainfall (first flush) and during the last 30 minutes of rainfall (steady-state). The first flush mean runoff for GUC-5 treatment was significantly higher than all other treatments. All other treatments; 50% woodchips and 50% compost blend (ECC-1.3, ECC-5), and hydroseeding (HS) had significantly lower runoff and erosion rates compared to topsoil (TS) and compost manufactured topsoil (CMT) at first flush and steady-state. Furthermore, there were no performance differences between 1.3 cm and 5 cm compost applications at first flush or steady-state. The results of this project indicate that particle size, soil moisture capabilities, and time at which rainfall is applied affect surface runoff. TxDOT specification of using ECC at 5 cm depth on a max of 3:1 slope should be reconsidered. An ECC application depth of 1.3 cm was effective in reducing first flush runoff and interrill erosion rates.

In Taiwan, swine wastewater has become one of the major causes of the deterioration of surface water quality. To minimize the operational and maintenance cost of the conventional wastewater treatment utilities, less expensive natural treatment systems (e.g., aquatic plant treatment system) have been proposed to enhance the efficacy of existing three-stage treatment system (solid separation followed by anaerobic and aerobic treatment). Using the natural treatment system is an appropriate technology for treating livestock wastewater in tropical or subtropical regions or developing countries because it is inexpensive, easily maintained, and has environmentally friendly and sustainable characteristics. The main objectives of this study were to (1) examine the efficacy and capacity of using aquatic plant treatment system to polish the treated wastewater to meet the discharge standards in Taiwan (COD = 600 mg/L, BOD = 80 mg/L, and SS = 150 mg/L), (2) evaluate the potential of reusing the treated wastewater, (3) evaluate the feasibility of replacing the aerobic treatment process contained in the three-stage system with the aquatic plant system, and (4) improve the efficiency of sludge (obtained from the three-stage treatment system) composting process. In this study, a hog farm was selected as the case study site. An aquatic plant unit [13.5 (L) ¡Ñ 4 (W) ¡Ñ 3 (D)] planted with Eichhornia crassipes (water hyacinth) was placed after the aerobic system for wastewater polishment. Influent and effluent sa mples from each unit were collected and analyzed for water quality parameters including chemical oxygen demand (COD), biochemical oxygen demand (BOD), and suspended solids (SS). Water samples were collected monthly during the 15-month investigation period. Results show that the averaged COD, BOD, and SS concentrations were approximately 708, 83, and 123 mg/L, respectively after the three-stage treatment scheme. The observed COD, BOD, and SS concentrations dropped to 518, 56, and 48 mg/L, respectively which could meet the discharge standards. Thus, the aquatic plant treatment system played an important role in meeting the discharge standards for swine wastewater. More than 99% of all pollutants were removed by the three-stage system followed by the aquatic plant system. The effluent from the treatment system has been used for hog farm cleaning. Thus, the aquatic plant system has the potential to be applied as the final polishment process to enhance the treatment efficacy of swine wastewater. Results also show that it is feasible to replace the aerobic treatment process with the aquatic plant system from the cost and regulation compliance point of view. Results from the composting study show that rice straws could enhance the activity of microorganisms and also cause the increase the quantity of potassium in the compost pile. Moreover, mixing the water hyacinth in the compost pile could increase the quantity of nitrogen and phosphorous. Results also reveal that using ceramic bioballs as the filling materials could minimize the composting time due to the increase of permeability in the piles.

Waste management in the leather industry worldwide is an issue of major importance for both solid and liquid wastes. It has been recognised that there are major environmental impacts from the poorly managed disposal of such wastes and these have a clear health impact upon human society. Within Europe, under EU driven legislation, the costs of wastes management are increasing rapidly and there is a clear need to research improved methods to cost effectively deal with leather industry wastes. Biodegradation (anaerobic), as a management option, of solid wastes from the leather industry is an area that is attracting increased interest in recent years as being a technique that has wide public acceptability as well as process efficiency. However, tanning agents that prolong the lifetime of leather goods have a negative impact on biodegradation and this needs to be addressed before efficient treatment can occur. To drive the agenda this research has the aims of • Highlighting the effects of tanning agent on anaerobic digestion. • Understanding the mechanism(s) by which different leather tannages can biodegraded. • Developing a process to reverse the action of tannage. Leather solid wastes were anaerobically digested using Serum Bottle Assays (SBA). The effect of a range of vegetable, mineral and aldehyde tanning agents of leather on the rate of anaerobic digestion was assessed. Common tanning agents used included; myrica, valonea, glutaraldehyde and chrome. To further identify key factors for cost effective anaerobic digestion, tanned hide powders and tanned leathers were also pre-treated using autoclaving, liming, enzymes etc, in an attempt to determine whether tannage may be reversed. Major techniques used in the research include: anaerobic digestion, Biochemical Methane Potential (BMP), Total Solids contents (TS), Gas Chromatography (GC) and Gas Chromatography Mass Spectrometry (GC-MS). Hydrolysable tannins are less resistant to anaerobic digestion than condensed tannins. However, enzymatic pre-treatment reduces the resistance and this offers a new effective pre-treatment route. Thermal pre-treatment also decreased resistance to anaerobic digression especially for chrome, glutaraldehyde, myrica and tannic acid tanned leathers. Chemical pre-treatment also generally lowered the resistance to anaerobic digestion. Selective pre-treatment offers a means of improving the cost effectiveness of anaerobic digestion of leather and therefore enabling a new waste management method to be adopted by the industry. A relationship emerges, in some cases, between chemical structure of tanning agent and inhibition of anaerobic digestion. This offers the possibility of producing new, designed organic tanning agents with, suitable properties, to be adopted by the industiy, The research agenda within the leather industry is still ongoing and recommendations for future research are addressed

Land application of biosolid or industrial compost raises concerns regarding heavy metal accumulation in soils, plants and free-ranging livestock. A strip-split plot design evaluated two levels of sewage sludge (22/44 t ha-1) and municipal solid waste (21/42 t ha-1) compared to nitrogen fertilizer and an unfertilized control. Treatments were evaluated with three levels of limestone (CaCO3 at 0, 3 and 6 t ha-1) over two years corn seeded no-till. Swiss Chard cultivated in field soil samples within a greenhouse monitored heavy metal bioavailability. Compost amended soil was incorporated into chicken feed to simulate soil ingestion in a free-range production system. Compost application increased total soil Pb over time yet decreased both available soil and corn plant Cu levels over time. No heavy metal accumulation was observed in Swiss Chard or poultry tissue. Biosolid composts containing elevated Cu or Pb levels can be safely used for crop or free-range broiler production.

Bioremediation is the process whereby the degradation of organic polluting compounds occurs as a result of biochemical activity of macro- and microorganisms. Bioremediation of hydrocarbon contaminated soils can be practised in situ or ex situ by either stimulating the indigenous microorganisms (biostimulation) or introducing adapted microorganisms which specifically degrade a contaminant (bioaugmentation). This investigation focused on ex situ remediation processes with special attention to the processes and microbiology of landfarming and thermal bioventing. Landfarming was investigated at pilot-scale and full-scale, and thermal bioventing at laboratory and pilot-scale. This study indicated that pilot-scale bioremediation by landfarming was capable of effecting a total petroleum hydrocarbon concentration (TPHC) reduction of 94% (m1m) from an initial concentration of 320 gkg-I soil to 18 gkg-I soil over a period of 10 weeks. Reactors receiving biosupplements showed greater rates of bioremediation than those receiving nutrients. Promotion of TPHC catabolism by addition of a commercial or a site-specific microbial biosupplement was similar. Seedling experiments proved that bioremediation did not necessarily leave the soil in an optimal condition for plant growth. The full-scale landfarming operation reduced the TPHC concentrations from 5 260 - 23 000 mgkg- I to 820 - 2335 mgkg- I soil over a period of 169 days. At full-scale, the larger fraction of more recalcitrant and weathered petroleums. and the less intensive treatment resulted in a slower rate of TPHC reduction than was found in the pilot-scale study. Three distinct decreases in the TPHC were observed during the full-scale treatment. These presented an ideal opportunity to investigate the microbiology of the soil undergoing treatment. The dominant culturable microorganisms were isolated and identified. The bioremediation process was dominated by Bacillus and Pseudomonas species. The method used to study the population was, however, biased to culturable, fast growing microorganisms which represent a small portion of the total microbial population. For this reason, a method to study the total eubacterial population in situ with rRNA targeted oligonucleotide probes was adapted and found to be a valuable technique. Soil microorganisms respiratory activity was investigated at different times in the full-scale treatment. A clear correlation between activity and degradation was recorded. The effect of a supplement. anaerobically digested sludge, was also assessed by this method. Thermal bioventing was investigated as an ex situ in-vessel treatment technology for small volumes of highly contaminated soils. This proved to be a viable technique for the bioremediation of petroleum hydrocarbons at laboratory-scale. Volatilisation contributed to at least 40% of the reduction. Of the two supplements evaluated. dried sludge promoted degradation to a greater extent than chicken manure. The pilot-scale study proved that a chemical contaminant reduction of at least 50% could be achieved in 13 weeks by thermal bioventing. Of the supplemented reactors. the presence of dried sludge and commercial biosupplement etfected the largest contaminant decrease. As a possible supplement to increase the rate of bioremediation. dried anaerobically digested sludge was more effective than chicken manure. A parallel laboratory-scale experiment gave similar results. Gravimetric analyses were found to be conservative indications of the remediation process. The results of this study shed some light on our. still. limited understanding of bioremediation. The gap between the technology in the laboratory and field was narrowed and a better understanding of the soil microbiology was achieved. Due to the limited control of environmental parameters in the case of landfarming. thermal bioventing was investigated and proved to be an effective alternative. The latter technology is novel in Southern Africa. / Thesis (Ph.D.)-University of Natal, Pietermaritzburg, 1996.