Addition Of Municipal Solid Waste Compost Research Articles

Stabilising fluoride in contaminated soils with monocalcium phosphate and municipal solid waste compost: microbial, biochemical and plant growth impact.

This study evaluated the influence of a municipal solid waste compost (MSWC) and monocalcium phosphate (MCP), alone or combined, on the mobility, toxicity, bioavailability and health risk of fluoride (1000mg F-·kg-1) in an artificially polluted soil (pH 7.85). The addition of MCP (0.2% w/w) and MSWC (1% w/w) (alone and combined) to the contaminated soil reduced water-soluble (e.g. by more than 50% in MCP and MCP + MSWC-treated soils) and exchangeable F- fractions and increased the residual one. The addition of MSWC and MSWC + MCP to the contaminated soil significantly increased microbial biomass C (SMB-C; 1.3-3.6-fold) while all treatments increased the abundance of culturable heterotrophic bacteria (up to twofold in MSWC + MCP). Overall, dehydrogenase, β-glucosidase, urease and phosphomonoesterase activities were enhanced in treated soils and positively correlated with SMB-C, but not with labile F-. All treatments increased carrot yield (up to 3.4-fold in MSWC + MCP), while bean growth was significantly enhanced only by MCP and MCP + MSWC (~ twofold). The opposite trend applied for F- uptake which was especially reduced in the edible part of carrot after soil amendment. A limited influence of MCP and MSWC on hazard quotient (HQ), due to bean and carrot consumption, was also recorded (i.e. HQ generally > 1). Results suggest that MCP and MSWC can be used in the recovery of soil chemical, microbial and biochemical status of F-rich agricultural soils. They also indicate that the bean and carrot cultivars employed in this study are likely unsuitable in such soils due to high F- uptake in edible parts.

Mobility, bioaccessibility and toxicity of potentially toxic elements in a contaminated soil treated with municipal solid waste compost

The aim of this study was to assess the influence of a municipal solid waste compost (MSWC) on the mobility, bioaccessibility and toxicity of several potentially toxic elements (PTE), i.e. Pb (15,383 mg kg−1), Zn (4076 mg kg−1), Cu (181 mg kg−1), Sb (109 mg kg−1), Cd (67 mg kg−1) and As (49 mg kg−1), present in a contaminated sub-acidic soil (pH = 5.93).The addition of MSWC at 2 and 4% rates significantly decreased the labile fractions of PTE (with the exception of Cu and As) and at the same time increased the residual fractions of Zn and Sb. In-vitro tests also showed that compost amendment was able to decrease Cd and Cu gastric bioaccessibility, with respect to untreated soil (−19 and 13% of Cd and Cu in MSWC-4% respectively), while a significant increase of As intestinal bioaccessibility was recorded. This increment was attributed to the pH rise (up to 7.0) during the in-vitro intestinal phase, which likely favoured a release of the arsenic non-specifically bonded to MSWC. Soil enzyme activities, i.e. dehydrogenase and β-glucosidase, were significantly enhanced in MSWC-amended soils (i.e. up to ~6.0 and 1.4 times higher in MSWC-4% than in control soil, respectively), as well as soil basal respiration, and the potential metabolic activity and catabolic versatility of soil microbial communities (as assessed by the Biolog ecoplate community level physiological profile).Overall, the results obtained suggested that MSWC, particularly at 4% rate, could be useful to stabilise PTE in sub-acidic contaminated soils and to increase the microbial activity and functionality in these latter soils.

Metal(loid)s immobilization in soils of Lebanon using municipal solid waste compost: Microbial and biochemical impact

Organic based amendments can be used to reduce metal(loid)s mobility in polluted soils and alleviate possible toxicity phenomena towards soil microbiota. Therefore, the objectives of this study were to evaluate the influence of municipal solid waste compost (MSWC) on the mobility of metal(loid)s in different contaminated soils and to determine the amendment effect on selected soil biochemical and microbial features. To this aim, MSWC was added at two rates (1 and 3% w/w) to different soils sampled in distinct regions of Lebanon (Halba and Terbol, i.e. HS and TS respectively) polluted with metal(loid)s such as As (total concentrations between 31 and 54 mg·kg−1) and Sb (between 93 and 120 mg·kg−1), and trace metals such as Ni, Cr and Zn. After two months of soil-amendment contact, compost addition at both rates significantly increased the non-extractable fractions of As, Sb, Ni, Cr and Zn (e.g. +25% of residual Sb in TS-MSWC 3% with respect to untreated TS), while decreased the environmentally-relevant water soluble and exchangeable fractions of all the metal(loid)s. This effect was more relevant for both soils when 3% MSWC was applied. The amendment addition similarly affected the community level physiological profile (Biolog CLPP) of the respective soil culturable microbial communities, which however showed an opposite trend in the two soils. In particular, compost addition increased the metabolic potential and catabolic versatility of the HS microbial community (compared to the untreated control), while the same proxies were significantly reduced in the amended TS soil. Differently, soil dehydrogenase (DHG), β-glucosidase (β-GLU) and urease (URE) activities were significantly enhanced in both soils treated with compost (e.g. + 17, 45 and 27% for DHG, URE and β-GLU in TS-MSWC 3% with respect to untreated TS). The results obtained showed that the addition of MSWC, particularly at the 3% rate, was effective at fixing the metal(loid)s present in both soils, had a substantial influence on the structure of the soil microbial communities and a positive effect on soil functionality. Taken together the results presented suggest that MSWC can be used as an alternative and environmental friendly amendment for the in situ remediation of metal(loid)s-polluted soils.

Evaluation of Municipal Solid Waste Compost and/or Fertigation as Peat Substituent for Pepper Seedlings Production

Pepper (Capsicum annuum L.) seed germination and seedling growth using municipal solid waste compost (MSWC) in various proportions was examined. MSWC extracts (10− 0 up to 10− 6 dilutions) were evaluated for seed priming/germination in Petri dishes. The MSWC extracts at 10− 1–10− 6 showed similar seedling germination, whereas extracts at 10− 1–10− 3 accelerated root radical length compared to the control treatment. However, pure extracts (at 10− 0) almost failed seed germination. Under nursery conditions, six substrates were prepared from commercial peat and MSWC and were further assessed in conjunction with the nutrient application as basic fertilizer (BF) or hydro fertilizer (HF). The addition of MSWC into peat inhibited seed emergence and increased the mean germination time, while fertigation accelerated seed emergence at 15% addition of MSWC. Addition of > 30% MSWC reduced seedling height, leaf number and fresh weight. BF and HF increased fresh weight in seedlings grown in 15% MSWC. Leaf chlorophyll and total carotenoids content decreased in > 60% MSWC into the peat. The greatest leaf photosynthetic rate was found with the application of HF, while higher leaf stomatal conductance and leaf internal CO2 concentration were found in plants grown without fertilizers for both 15 and 45% of MSWC addition. The K content decreased, Na content increased, while P content did not differ with MSWC addition. Fertigation improved seedlings’ nutritive status. No visual phytotoxicity was observed macroscopically. Low content (15–30%) of MSWC may act as alternative substitute to peat with more positive effects observed, if nutrients are provided through HF rather than BF.

Municipal solid wastes and mineral fertilizer as an eggplant transplant medium

The fertigation and/or municipal solid waste compost (MSWC)studied in eggplant seedlings. MSWC extracts (between 10-1 and 10-2) accelerated seedling germination. Under nursery conditions, six substrates prepared from commercial peat and MSWC and were further assessed in conjunction with the nutrient application as basic fertilizer (BF) or hydro fertilizer (HF). The addition of MSWC into the substrate inhibited seed emergence and mean germination time, while fertigation accelerated seed emergence in 15% MSWC. Addition of 60% MSWC reduced seedling height, leaf number and fresh weight. BF increased fresh weight in seedlings grown in 15% MSWC. Leaf Chlorophyll b content decreased but total carotenoids increased by adding MSWC into the substrate. The K content decreased, Na content increased while P content did not differ with MSWC addition. Fertigation benefits seedlings nutritive status. Low content (15-30%) of MSWC may act as alternative substitute of peat with more positive effects observed if minerals provided through BF rather than HF.

Carbon and Nitrogen Mineralization and Humus Composition Following Municipal Solid Waste Compost Addition to Laterite Soils under Continuous Cassava Cultivation

A glasshouse incubation experiment was conducted to study the carbon (C) and nitrogen (N) mineralization of municipal solid waste compost (MSWC) added at differential rates to a laterite soil where cassava has been continuously cultivated for the past 10 years. The rate of C mineralization from added substrates increased with increasing rates of addition of MSWC. Available N significantly increased with increase in the rate of application of MSWC. There was a decreasing trend in E465/E665 ratio of humic acid as we increased the rate of application of MSWC from 2.5 to 20 t ha−1. The Cross Polarization Magic Angle Spinning (CPMAS) 13C NMR spectral analysis revealed that there are differences in the rate of humification of added MSWC, and application of MSWC at 15 t ha−1 resulted in least humification with the greatest alkyl C, lowest aromatic C, and greater O-alkyl C content. The decomposition rate (R) was found to be greater for this treatment. The residual C in soil was found to increase over time coincident with greater rates of MSWC application, indicating increased C stabilization, which could improve soil quality.

Deployment of Municipal Solid Wastes as a Substitute Growing Medium Component in Marigold and Basil Seedlings Production

The possible use of municipal solid waste compost (MSWC) in the production of marigold and basil seedlings examined. Six medium prepared from commercial peat (CP) and MSWC (0, 15, 30, 45, 60, and 100% v/v). There was not any plant growth when MSWC used alone (100%). The addition of MSWC in low content (15% and 30%) improved seed emergence for marigold and basil respectively, while greater content revealed opposed impacts. Mean emergence time delayed as MSWC content increased into substrates. Addition of MSWC (especially in content greater than 30%) into CP reduced (from 34 to 64%) plant height, leaf number and stem diameter as a consequence reduced plant fresh weight (plant biomass) for both species. The number of lateral stems decreased (up to 81%) in basil when MSWC added into substrate mixtures. Chlorophyll b content decreased (up to 58%) in substrates with MSWC content greater than 15% or 30% while similar reduction observed in content of Chlorophyll a and total carotenoids for basil with MSWC > 60%. However, Chlorophyll a and total carotenoids content increased as MSWC content increased for marigold. K and Na leaf content increased but P equivalent decreased as MSWC content increased. Nursery-produced basil and marigold seedlings grown in 15% MSWC; displayed quality indices similar to those recorded for conventional mixtures of peat and may act as component substitute.

Effect of Municipal Solid Waste Compost and Sewage Sludge on Enzymatic Activities and Wheat Yield in a Clayey-Loamy Soil

In the Mediterranean region, difficult climate conditions and inadequate land management have led to a reduction of the organic matter content of soils. As a solution, municipal solid waste (MSW) compost and sewage (S) sludge were investigated for their effectiveness in maintaining soil fertility. Clayey-loamy soil was amended with 0, 40, and 80 t ha−1 of MSW compost or S sludge and cultivated with Triticum durum. Soil was sampled 15 and 70 days after sowing, and the activities of arylsulphatase, phosphatase, dehydrogenase (DH), β-glucosidase (β-GLU), urease, and catalase (CAT) were assayed. The wheat was harvested after 68 days, then soil properties as well as plant growth and K+ and Na+ contents were determined. Almost all soil enzymatic activities were significantly (P < 0.01) affected by amendment dose, sampling time, and their interaction. At 15 days, MSW compost had a moderate effect on DH, β-GLU, and CAT activities under both applied doses. A significant increase of all the measured activities was observed after 70 days at either 40 t ha−1 or 80 t ha−1 (ranged between 16%-160% and 10%-81%, respectively), likely providing a long-term nutrient release. The activities of arylsulphatase, phosphatase, DH, CAT, and β-GLU (only with the lower dose) were strongly enhanced at 15 days after S sludge treatment. After 70 days, an increase of the enzymatic activities occurred with S sludge, although its beneficial effect was reduced mainly at 80 t ha−1 presumably because of the presence of micropollutants in the sludge. Plant growth was significantly improved by 40 and 80 t ha−1 of compost (93% and 126%, respectively); however, less impact was observed with S sludge. Overall, the results suggest that addition of MSW compost could enhance the fertility of degraded soils and promote plant growth.

Ameliorative Effect of Municipal Solid Waste Compost on the Biological Quality Of Mediterranean Salt Lake Soil

Different loads of municipal solid waste compost (MSWC) were applied to hyper saline salt lake soil under laboratory conditions to monitor biological soil quality. Microbial biomass-C (MBC), catalase, dehydrogenase, urease, alkaline phosphatase, arylsulfatase, and β-glycosidase activities were analyzed following 14, 30, and 50 days of incubation. In general, MBC and the oxidoreductase and hydrolase enzyme activities were significantly enhanced by addition of MSWC at 20 and 40 t ha−1 doses, but they decreased at 120 t ha−1. Overall, the results show that the addition of MSWC to hyper saline soils can improve soil biological quality, in spite of its high salt content, which is an important step in any attempt to use them as biosaline agricultural soils. However, substances such as heavy metals in MSWC could limit the use of compost for this purpose; consequently, analysis of MSWC is recommended prior to its use.

MUNICIPAL SOLID WASTE COMPOST (MSWC) AS A SOIL AMENDMENT IN IRRIGATED VEGETABLE PRODUCTION

A field study was conducted to evaluate the water conservation aspects for vegetable production associatedwith field incorporations of municipal solid waste compost (MSWC). In June 1992, MSWC was incorporated into a sandysoil as a soil amendment at the University of Florida Gulf Coast Research and Education Center, Bradenton, Florida.Drip-irrigated and subirrigated vegetable production studies were conducted during autumn 1992, spring 1993, autumn1993, and spring 1994 seasons. Green peppers were grown during the autumn seasons and fresh market tomatoes wereproduced during the spring seasons. MSWC was applied at various rates in drip-irrigated and subirrigated plots. Dripirrigation was applied based on crop water use estimated from reference evapotranspiration data and crop coefficients. Afully enclosed subirrigation system was used in the subirrigated plots with the water table controlled at an average depthof 0.60 m below the soil surface. Nitrogen fertilizer was applied to each of the MSWC, drip-irrigated, and, subirrigatedplots. Incorporated MSWC was still immature (based on measured C/N ratios > 30) and reduced autumn 1992 drip-irrigatedpepper yields and reduced plant growth. By spring 1993 the incorporated MSWC had field matured and resultedin significantly increased tomato plant size and fruit yields in the spring of 1993 and all other subsequent drip-irrigatedtrials. The 134 t ha 1 MSWC rate increased spring 1993 and 1994 tomato yields by 27% and 18%, respectively, andautumn 1993 peppers by 17% over the non-amended plot yields. Drip-irrigated pepper yields were not affected byirrigation rate or applied nitrogen level. While drip irrigation rate did not affect total tomato fruit yield in any of theseasons, yield of extra large tomato fruit was greater with higher levels of applied water in the spring of 1994, and thehigher applied nitrogen levels increased marketable fruit yields by 13 to 14%.<br><br>In general, amending a sandy soil with MSWC significantly improved plant growth and yield in drip-irrigatedvegetable production. However, applied nitrogen rate in the subirrigated fields did not affect fruit yield in any of theseasons. Autumn 1992 pepper yields and spring 1994 tomato yields in the subirrigated plots were reduced by the additionof MSWC and autumn 1993 pepper yields were greater with the addition of MSWC. MSWC increased yield of extra largetomato fruit in the spring 1993 season and reduced fruit size in the autumn 1993 pepper trial, but had no statistical effecton fruit size in any of the other seasons. Therefore, the subirrigated system results were not as conclusive as the drip-irrigatedresults. Furthermore, immature MSWC products should be incorporated into fields with sufficient maturationtime prior to planting.

Soil enzymatic response to addition of municipal solid-waste compost

Modifications of soil microbiological activity by the addition of municipal solid-waste compost were studied in laboratory incubations. Three composts were compared, one lumbricompost and two classical composts with different maturation times. Organic C mineralization and nine enzyme activities (dehydrogenase, peroxidase, cellulase, β-glucosidase, β-galactosidase, N-acetyl-β-glucosaminidase, protease, amidase, and urease) were determined in the composts and the amended soil. Initial enzyme activities varied in the soil according to the sampling date (winter or summer) and were greater in the composts than in the soil, except for urease. Generally, the youngest compost exhibited greater activity than the oldest one. In the amended soil, the composts did not increase enzyme activity in an additive way. Dehydrogenase, the only strictly endocellular enzyme, was the only one for which the activity in the amended soil increased significantly in proportion to the addition of compost. During the incubations, C mineralization and dehydrogenase activity were significantly correlated, indicating that dehydrogenase was a reliable indicator of global microbial activity. Peroxidase activity in the soil remained constant, but increased in the composts and amended soil. Addition of the oldest compost had no effect on the activity of the C cycle enzymes, but the youngest compost increased creased soil activity at the higher application rate. Enzymes of the N cycle were stimulated by all compost amendments, but the increase was only transient for amidase and urease. Lumbricomposting had no marked effect on compost enzyme activity, either before or during the incubation.

Effect of the addition of municipal solid-waste compost on microbial biomass and enzyme activities in soil

Changes in the content of C, N, P, and S in the soil biomass and in phosphatase, urease, protease, deaminase, and arylsulphatase activity, induced by amendment with municipal solid-waste compost, were determined in a clay loam soil during 1 year of incubation at 25° and 35°C.