Biosolids Compost Research Articles

Evaluation of composted biosolid waste as an amendment to a standard horticultural nursery mix for container grown Callicarpa and Ilex production

Evaluation of composted biosolid waste as an amendment to a standard horticultural nursery mix for container grown Callicarpa and Ilex production

Quantification of Water Extractable Contaminants From Food Waste and Biosolids Blends At Different Stages of Composting

Rainfall runoff and leachate from windrows composting organic wastes carry nutrients and pathogens. Water extractability of contaminants in compost impacts the design of runoff treatment systems. This paper reports maximum water extractable nutrients, pathogens, and regulated metals from biosolids and food waste composts as measured from a snapshot sampling of windrows at different stages of stabilization at a commercial operation at a single point in time. Results show that unstable composts released larger amounts of fecal coliform (13,100 to 19,000 Most Probable Number per g of sample, MPN g−1) than stable composts (6 to 7 MPN g−1). Maximum water extractable C was 4690 and 5990 mg kg−1 in food waste and biosolids composts, respectively. In both composts, extractable amounts of C decreased with increased stability of compost, but was not so for extractable N or P. Significantly greater P was extractable from food waste (9.7 to 12.5% of total P) than biosolids composts (2.8 to 3.9%). Heavy metal extractability was highest for Ni (5.3 to 13.4% of total present) and Cd (8.5 to 29%).

Heavy Metal Mobility in Polluted Soils: Effect of Different Treatments

The effects of biosolid compost and phytoremediation applied on the leaching of cadmium, copper, lead and zinc, through the different horizons of a superficially polluted soil were determined. The soil was from the Province of Buenos Aires, Argentina. It was contaminated with cadmium copper, lead and zinc. Leaching columns were used with three different horizons: A: 0.12 m A horizon, B: 0.12 m horizon A+0.15 Bt horizon and C: 0.12 m A horizon+0.15 m Bt horizon+0.13 m BC horizon. The treatments were (1). Witness (contaminated soil), (2). contaminated soil+plants (Plant), (3). contaminated soil+50 Mg has-1 biosolid compost (Compost) and (4). contaminated soil+50 Mg has-1 biosolid compost+plants (Compost-Plant). The leached ones were gathered after incorporating to the columns the following volumes of water A: 1000 mL, B: 1200 mL and C: 2000 mL. Leachates were obtained out after harvesting vegetal material. It was found that horizon Bt presents a barrier to metal leaching. Both concentration of clay and type of clay appears to immobilize heavy metals in those soils. The clay content over 40% and/or 53.4 g smectite g-1 soils reduce the heavy metal leaching. The application of organic amendment or occurrence of plant eventually used in remediation techniques did not influence on the leaching of metals.

Trace elements, pH and organic matter evolution in contaminated soils under assisted natural remediation: A 4-year field study

A 4-year study was undertaken on the effect of three amendments (biosolid compost (BC), sugar beet lime (SL), and combination of leonardite plus sugar beet lime (LESL)) on reclamation of a moderately trace element-contaminated soil under field conditions. Results showed that organic C increased in BC and LESL treatments. BC and SL treatments increased soil pH and reduced CaCl 2-extractable metal concentrations more efficiently. At the end of the experiment, CaCl 2-extractable metal concentrations decreased and were similar in all treatments pointing out the importance of the natural remediation processes in contaminated soils. Addition of amendments showed no clear reduction in EDTA-extractable trace element concentrations, even, BC and LESL subplots showed some little increase of these elements with time. Amendments did not cause any change in total trace element concentration in soil. Addition of amendments could be a successful and reliable long term technique for stabilization of trace elements in contaminated soils at a field scale with minimum maintenance.

Application of molecular technologies to monitor the microbial content of biosolids and composted biosolids

Disposal of human biosolids is a source of concern for public health and the environment. Composting appears to be an interesting alternative to traditional disposal methods as it can decrease the load of human pathogenic microorganisms often present in biosolids and yield an end-product rich in nutrients for use as a soil supplement. Assessing the exact microbial content of biosolids, both for biosafety and operational reasons, has traditionally relied on the use of standard microbiological methods. Recent developments in molecular-based technologies now offer more rapid and specific monitoring of microorganisms in biosolids than culture-based methods. In this study, denaturing gradient gel electrophoresis (DGGE) was adapted to monitor the succession of bacteria in composted biosolids through different steps of compost production. Secondly, a TaqMan quantitative real time PCR (qPCR) approach was developed to detect and quantify the presence of Salmonella species, a model human pathogenic bacterium, susceptible to be found in biosolids. DGGE results indicated that the bacterial content of composted biosolids of different ages belongs to various taxa and significantly changes with age. qPCR results indicated that the quantity of Salmonella species found in composted biosolids ranging from 1 to 24 months significantly decreases with composting time.

Trace elements in wild grasses: a phytoavailability study on a remediated field

There have been significant efforts to establish a widely usable method for the prediction of trace element bioavailability in soil. In this work, we used extraction with 0.01 M CaCl2 and 0.05 M ethylenediaminetetraacetic acid (EDTA) to estimate bioavailable concentrations of As, Cd, Cu, Pb, and Zn in a soil moderately contaminated with trace elements 1 and 2 years after the application of three amendments. The experiment took place in a field plot of a soil affected by the toxic spill of the Aznalcóllar mine. Four treatments were established: three with amendments (biosolid compost, sugar beet lime, and a combination of leonardite plus sugar beet lime) and a control without amendment. Trace element concentrations of two representative species in each year (Lamarckia aurea and Poa annua in 2004 and Lamarckia aurea and Bromus rubens in 2005) were analyzed. The results showed a positive effect of the amendments both on soil and vegetation. Trace element concentrations in plants growing in the amended subplots were lower than those in plants from nonamended subplots. As a rule, concentrations of CaCl2-soluble Cd, Cu, and Zn in soil were positively correlated with trace elements in plants, whereas EDTA extraction was scarcely correlated with plant concentration. For species of grasses, especially L. aurea, CaCl2 seems to be a more suitable extractant to predict trace element bioavailability in this contaminated soil.

Biofiltration of High-Strength Exhaust from Biosolids Composting: Lessons Learned and Demonstration of Successful Treatment

Biofiltration of High-Strength Exhaust from Biosolids Composting: Lessons Learned and Demonstration of Successful Treatment

Effectiveness of Field Olfactometry and Neighbor Control to Reduce Odor Annoyance from Biosolids and Municipal Solid Waste Composting

An odor monitoring study was carried out with fifteen voluntary residents living in the vicinity of an source-separated municipal solid waste (MSW) composting plant (10 4 T/y) and an aerated channel biosolids composting facility (10 4 T/y). In the period June 2005-October 2007 residents recorded odor annoyance of up to fourteen different odors three times a day (on a 1 to 5 scale). All residents were nose-calibrated three times with the Odor Sensitivity Test (St. Croix Sensory, Inc.).Additionally, five residents were trained to use a field olfactometer (Nasal Ranger™) to measure ambient odor dilutions to threshold (D/T) at home. They participated in several field intercomparisons at the two odor sources obtaining excellent coefficients of variation (< 40%) against a certified odor inspector. Unannounced field D/T inspections and resident measurements with the Nasal Ranger™ showed very good agreement in both ambient odor strength and time of day. For biosolids odor the highest value recorded at the site was 30 D/T (475 m from the source) while for source-separated MSW odor was 7 D/T (700 m from the source). Good correlations were found between the monthly-averaged Odor Annoyance Index (OAI) and the monthlyaveraged global D/T measured around each odor source by a certified odor inspector. Random field D/T inspections at the site agreed also quite well with the daily OAI for each odor source. By the end of 2006 new management practices were implemented in both facilities and major structural changes were undertaken in 2007. The effectiveness of field olfactometry and neighbour control in providing meaningful and objective indicators of odor annoyance reduction following those corrective actions has kept neighbours patient and supportive of the communication program established in June 2005. Odor annoyance in the neighbourhood is expected to reach acceptable levels in the first semester of 2008.

Modern Approaches to Enhance Biosolids Composting

Modern Approaches to Enhance Biosolids Composting

Development of a Large-scale Biosolids Composting Facility in California

Development of a Large-scale Biosolids Composting Facility in California

Compost Amended Soil Treatment for Mitigating Highway Shoulder Desiccation Cracks

Certain types of compost materials have fibrous characteristics that exhibit moisture affinity suggesting that they could be used to stabilize expansive soils to control desiccation cracks. In order to understand shrinkage cracking control mechanisms of compost amended soils, a field study was designed with two compost types, dairy manure compost (DMC) and biosolids compost (BSC). Composts were mixed with topsoil at different proportions to form four types of compost manufactured topsoils (CMTs). Seventeen CMT test plots of different treatment widths and thicknesses including a control plot with no CMT cover material were constructed at Stephenville, Tex. and these sections were heavily instrumented with moisture and temperature sensors. Data from sensors, digital image based surface cracking studies, visual observations of shoulder cracking, and surficial erosion surveys of all test sections were collected and statistically analyzed and these results indicated that the BSC amendments provided the best subsoil enhancements by controlling moisture and temperature fluctuations from the high temperature environment, thereby reducing shrinkage cracks in subsoils and in the adjacent paved highway shoulders. The DMCs were less effective in mitigating shrinkage cracking due to low amounts of fibrous or organic matter. Both design and construction specifications for CMTs were also developed. This application will enhance recycling efforts by converting wastes into usable compost, mitigate future pavement cracking, and lessen premature maintenance costs.

Field Test of In Situ Soil Amendments at the Tar Creek National Priorities List Superfund Site

A range of soil amendments including diammonium phosphate fertilizer (DAP), municipal biosolids (BS), biosolids compost, and Al- and Fe-based water treatment residuals were tested on Pb-, Zn-, and Cd-contaminated yard soils and tailings at the Tar Creek NPL site in Oklahoma to determine if amendments could restore a vegetative cover and reduce metal availability in situ. For the yard soils, all amendments reduced bioaccessible (assessed with a physiologic-based extraction method) Pb, with reductions ranging from 35% (BS+Al, DAP 0.5%, DAP+Compost+Al) to 57% (Compost+Al). Plant Zn (Cynadon dactylon L.) and NH4 NO3-extractable Cd and Zn were also reduced by a number of amendments. For the tailings, all amendments excluding BS reduced bioaccessible Pb, with the largest reductions observed in the DAP 3% and DAP3%+BS treatments (75 and 84%). Plant growth was suppressed in all treatments that contained DAP for the first season, with the highest growth in the treatments that included compost and biosolids. In the second year, growth was vigorous for all treatments. Plant Zn and Cd and extractable metal concentration were also reduced. A number of treatments were identified that reduced bioaccessible Pb and sustained a healthy plant with reduced metal concentrations. For the yard soil, Compost+Al was the most effective treatment tested. For the tailings, BS+DAP 1% was the most effective treatment tested. These results indicate that in situ amendments offer a remedial alternative for the Tar Creek site.

Effects of Organic Matter on Physical, Strength, and Volume Change Properties of Compost Amended Expansive Clay

In recent years, the recycling and composting of municipal solid wastes has gained acceptance as an alternative to landfilling and incineration. Compost materials have been used as soil amendments in landscaping, erosion control, expansive soil treatment, and turf management. Compost amended soils are enriched with decomposed organic matter and hence usually exhibit different strength and compressibility in soil behaviors. An experimental investigation was carried out on compost amended soils to understand the effects of decomposed organic matter on strength and volume change properties. Two types of composts, a biosolids compost and a dairy manure compost, and a control cohesive soil were chosen as test materials. Tests conducted on these materials showed that the presence of organic matter enhanced shrinkage resistance and shear strength at low compost proportions (20–30%). At high proportions (beyond 30%), the shear strength reached plateau conditions. One-dimensional vertical swell and secondary conso...

Forest soil rehabilitation with tillage and wood waste enhances seedling establishment but not height after 8 years

We evaluated soil conditions of rehabilitated log landings in the Interior Douglas-fir biogeoclimatic zone of British Columbia during the first 3 years after treatment and the growth of lodgepole pine ( Pinus contorta Dougl. ex Loud. var. latifolia Engelm.) on these log landings over 8 years. Rehabilitation treatments included combinations of tillage and the addition of either stockpiled topsoil or one of three organic amendments: hog fuel, sort-yard waste, and a wood waste – biosolids compost. The woody amendments were either applied as a surface mulch or incorporated into the soil after tillage. Tillage and addition of wood waste reduced soil bulk density and increased carbon content. Daytime soil temperatures in summer were lower under a hog fuel mulch than for the other treatments. The plots receiving hog fuel also had higher soil moisture content. One year after treatment, soil mechanical resistance for untreated soils, and those that were simply tilled, exceeded 2500 kPa for much of the growing season. Plots receiving wood waste had lower mechanical resistance. Use of wood waste in rehabilitation improved soil conditions and contributed to improved survival rates for planted lodgepole pine seedlings. Height growth after 8 years was not significantly affected by the treatments.

Transformation of 4-nonylphenol isomers during biosolids composting

4-Nonylphenol, a degradation intermediate of commercial surfactant and known endocrine disruptor, has been frequently detected at levels up to several thousand μg l −1 in surface waters and up to several hundred mg kg −1 (dry weight) in soil and sediment samples. Large quantities of 4-NP can be quickly sorbed by the organic rich solid phase during wastewater treatment and are concentrated in biosolids, a possible major source for 4-NP in the environment. Microbial transformation in culture studies followed different mechanisms for different 4-NP isomers, which have different estrogenic activity. Composting is a process of solid matrix transformation where biological activity is enhanced by process control. This approach has been used successfully in remediation of contaminated soils and sludges. In this study, the transformation kinetics of 4-NP and its isomers were characterized during biosolids composting. Five distinctive 4-NP isomer groups with structures relative to α- and β-carbons of the alkyl chain were identified in biosolids. Composting biosolids mixed with wood shaving at a dry weight percentage ratio of 43:57 (C:N ratio of 65:1) removed 80% of the total 4-NP within two weeks. At this biosolids/wood shaving ratio (B:WS), the transformation of total 4-NP and its isomers followed second-order kinetic. Higher B:WS ratios yielded significantly slower 4-NP transformation which followed first-order kinetic. Isomers with α-methyl-α-propyl structure transformed significantly slower than those with less branched tertiary α-carbon and those with secondary α-carbon, suggesting isomer-specific degradation of 4-NP during biosolids composting.

“In Situ” Amendments and Revegetation Reduce Trace Element Leaching in a Contaminated Soil

Various amendments and/or a plant cover (Agrostis stolonifera L.) were assessed for their potential to reduce trace element leaching in a contaminated soil under semi-arid conditions. The experiment was carried out in field containers and lasted 30 months. Five treatments with amendments (leonardite (LEO), litter (LIT), municipal waste compost (MWC), biosolid compost (BC) and sugar beet lime (SL)) and a plant cover and two controls (control without amendment but with plant (CTRP) and control without amendment and without plant (CTR)) were established. Drainage volumes were measured after each precipitation event and aliquots were analysed for pH, electrical conductivity (EC) and trace element concentrations (As, Cd, Cu, Pb and Zn). Soil pH and trace element extractability (0.01 M CaCl2) at three different depths (0–10, 10–20 and 20–30 cm) were measured at the end of the experiment. Incorporation of amendments reduced leaching of Cd, Cu and Zn between 40–70% in comparison to untreated soil. The most effective amendments were SL, BC and MWC. At the end of the experiment, extractable concentrations of Cd, Cu and Zn were generally lower in all amended soils and CTRP compared to CTR. Soil pH decreased and extractability of metals increased in all treatments in relation to depth. Results showed that use of these amendments combined with healthy and sustainable plant cover might be a reliable option for “in situ” stabilization of trace elements in moderately contaminated soils.

Quantification of Salmonella spp. in composted biosolids using a TaqMan qPCR assay

Composting is increasingly used to transform biosolids, obtained following wastewater treatment, into a more stable organic product that can be released in the environment. The process must however be closely monitored to assure that the end product meets the regulations set by environmental agencies with regards to the amount of pathogenic microorganisms present. In this study, a TaqMan qPCR approach targeting the invA gene was developed to monitor the presence of Salmonella spp. in composted biosolids. A validation step was first performed to evaluate the effect of compost age on the quantification of various concentrations of seeded Salmonella typhimurium. Secondly, qPCR was used to investigate the effect of composting time, varying from 1 month to 24 months, on the presence of Salmonella spp. naturally present in biosolids samples. Culture media were used in parallel to corroborate the results obtained by qPCR. The detection limit of the invA gene obtained experimentally from composts seeded with S. typhimurium was 5.8 copies or the equivalent of 5.8 CFU per qPCR reaction. Although the results indicated that compost age had a marginal effect on the detection of seeded S. typhimurium, the TaqMan qPCR approach was efficient at detecting and quantifying the amount of Salmonella spp. present in naturally contaminated composted biosolids of different ages. Results showed that there was a significant decrease in the amount of Salmonella DNA present in composted biosolids over time, which was also corroborated by the CFU counts obtained on the BSA culture medium. However, qPCR was more specific, robust and rapid to execute than performing counts on culture media. qPCR shows promise for routine examination of composted biosolids to ascertain that pathogenic microorganisms, including Salmonella spp., are decreased below acceptable limits before their application in the environment.

Compostaje de biosólidos de plantas de tratamiento de águas residuales

It was evaluated the bio solid composting in Canaveralejo Wastewater Treatment Plant in Cali - Colombia. Although the process was viable, the bulking agent (BA) incorporation improved the final product C/N relation. Municipal yard trimmings and sugar cane waste were the best bulking agent and amendment material, respectively. The B:BA:AM optimal relation, on percent, was 72:10:18. In terms of waste management and considering the increasing on the municipal wastewater treatment plants number, this study showed that the bio solid compost could be considered as a material with agricultural potential use; additionally when the option is just the bio solid final disposition, the composting process can reduce its disposal volume at 70%.

Prolonged compost curing reduces suppression of Sclerotium rolfsii

Composts have long been recognized to facilitate biological control of soil borne plant pathogens. Composts can introduce biocontrol agents into growth media and serve as a food base for their establishment and activity. Mature biosolids compost (a blend of sewage sludge and yard waste) was found to be suppressive to germination of the sclerotia of S. rolfsii on compost plates and also suppresses the disease development in bean plants ( Phaseolus vulgaris L.). Microscopic observations revealed that sclerotia placed on suppressive compost were attacked by mycoparasites. However, prolonged curing of compost negated this phenomenon. This research was aimed to study the changes in chemical and biological properties occurring during prolonged curing and their relation to compost suppressiveness. Correlations were found between the decrease and subsequent loss of suppression of sclerotia germination and the decrease in basal respiration, dissolved organic carbon (DOC) and NH 4 + concentrations, and the increase in NO 3 - concentration and specific UV absorbance. A shift of both bacterial and Ascomycetes populations as a consequence of curing was observed. Interactions between micro-organisms and their chemical environment are discussed.

Mineralization and N Fertilizer Equivalent Value of Composts as Assessed by Tall Fescue (Festuca arundinacea)

The capability to determine nitrogen availability of composts is necessary to ensure that such materials will provide sufficient fertilization to the growing crop and cause minimal environmental degradation. A greenhouse study using tall fescue as a bioindicator was used to evaluate nitrogen availability of two biosolids composts, two mixed yard waste-poultry manure composts, and one commercially-processed poultry litter. Five inorganic nitrogen (as NH4NO3-N) treatments applied at 0, 22.5, 45, 67.7, and 90 mg N/kg soil were employed to establish an N calibration curve. Yield, fescue biomass total nitrogen (as total Kjeldahl N (TKN)), and soil TKN and KCl extractable NO3−-N and NH4+-N concentrations of the organically amended treatments were compared to the inorganically fertilized treatments to determine amendment N mineralization rates and N fertilizer equivalent values (NFEV). Nitrogen mineralization rates were greatest in the poultry litter (21%) and Panorama yard waste compost (5%) amended pots. The NFEV of these amendments were 49% and 10%, respectively. Wolf Creek biosolids compost and Huck's Hen Blend yard waste compost immobilized N (−5% and 0.18%, respectively), and had percent NFEV of −0.66% and 0.19%, respectively. Rivanna biosolids compost immobilized N (−15%), but the NFEV was 30% due to the relatively high inorganic N content in the amendment. Nitrogen mineralization and NFEV were generally greater in amendments with greater total N concentrations and lower C:N values. The total N concentration and C:N values were less reliable variables in predicting N mineralization and percent NFEV when a significant portion of the total N was in the inorganic form. Nitrogen equivalency value and N mineralization for each amendment increased with time of sampling, indicating the potential for early season N insufficiency to plants fertilized with compost due to lack of synchrony between N mineralization and plant N needs.