Biodegradation of Weathered Petroleum Hydrocarbons Using Organic Waste Amendments

Extraction, transport, and processing of petroleum products have resulted in inadvertent contamination of soil. Various technologies have been proposed for removal of petroleum hydrocarbon contaminants, including biological techniques. Treatment of aged (weathered) petroleum compounds is challenging, as these wastes tend to be enriched with recalcitrant hydrocarbons. The purpose of the reported study was to investigate remediation of weathered petroleum via simulated landfarming using selected soil amendments. Soil contaminated by aged crude petroleum from well fields in the southern Zagros region in Iran was treated in combination with plant compost, papermill sludge, activated carbon, and molasses. Over 15 weeks, the greatest percentage removal (40%) of total petroleum hydrocarbons (TPH) occurred in the molasses treatment, followed by a 29% reduction in the plant compost treatment. The degradation constant (k), produced by a kinetic model, demonstrated the performance of the molasses over the other treatments applied; experimental data adequately fitted into first-order kinetics (k = 0.005 d−1, t½ = 71 d). Benzene decomposition was greatest (77 and 74%) in the molasses and activated carbon treatments, respectively, and was lowest in the papermill sludge treatment (41%). FTIR analysis revealed loss of benzene in all treatments. Bacterial counts were highest (4.9 × 106 CFU/g) in the plant compost treatment and lowest (1 × 105 CFU/g) in the untreated oil-contaminated soil. Based on the findings of the current study, it is possible to successfully conduct landfarming of aged petroleum deposits; however, it is recommended that common and inexpensive amendments such as molasses and plant compost be used when feasible.

Characterisation and evaluation of biochars for their application as a soil amendment

Biochar properties can be significantly influenced by feedstock source and pyrolysis conditions; this warrants detailed characterisation of biochars for their application to improve soil fertility and sequester carbon. We characterised 11 biochars, made from 5 feedstocks [Eucalyptus saligna wood (at 400°C and 550°C both with and without steam activation); E. saligna leaves (at 400°C and 550°C with activation); papermill sludge (at 550°C with activation); poultry litter and cow manure (each at 400°C without activation and at 550°C with activation)] using standard or modified soil chemical procedures. Biochar pH values varied from near neutral to highly alkaline. In general, wood biochars had higher total C, lower ash content, lower total N, P, K, S, Ca, Mg, Al, Na, and Cu contents, and lower potential cation exchange capacity (CEC) and exchangeable cations than the manure-based biochars, and the leaf biochars were generally in-between. Papermill sludge biochar had the highest total and exchangeable Ca, CaCO3 equivalence, total Cu, and potential CEC, and the lowest total and exchangeable K. Water-soluble salts were higher in the manure-based biochars, followed by leaf, papermill sludge, and wood biochars. Total As, Cd, Pb, and polycyclic aromatic hydrocarbons in the biochars were either very low or below detection limits. In general, increase in pyrolysis temperature increased the ash content, pH, and surface basicity and decreased surface acidity. The activation treatment had a little effect on most of the biochar properties. X-ray diffraction analysis showed the presence of whewellite in E. saligna biochars produced at 400°C, and the whewellite was converted to calcite in biochars formed at 550°C. Papermill sludge biochar contained the largest amount of calcite. Water-soluble salts and calcite interfered with surface charge measurements and should be removed before the surface charge measurements of biochar. The biochars used in the study ranged from C-rich to nutrient-rich to lime-rich soil amendment, and these properties could be optimised through feedstock formulation and pyrolysis temperature for tailored soil application.

Papermill biosolid and hog manure compost affect short-term biological activity and crop yield of a sandy soil

Soils used for intensive vegetable production often become depleted in their organic matter content, and consequently low in their microbial activity. Papermill sludge compost may be an efficient way to improve the biological activity of these soils. An experiment was initiated to determine the effects of a co-composted papermill sludge and hog manure (PHC), applied alone or in combination with mineral fertilizers (MF), on several biochemical properties and crop yield of a Bevin loamy sand (Orthic Humo-Ferric Podzol) located at Saint-Ubalde, province of Quebec, Canada. The PHC was applied in the spring of 1997 at rates of 0, 11.5, 23 and 34.5 Mg dry weight ha-1, with and without MF equivalent to 150 N-200 P2O5-200 K2O kg ha-1. Potatoes (Solanum tuberosum L.) were planted the first year and the residual effect of PHC was evaluated on a spring wheat (Triticum aestivum L.) crop in 1998. Enzymatic activity of β-glucosidase, β-galactosidase, acid phosphatase, urease and fluorescein diacetate hydrolysis, microbial biomass C (MBC) and CO2-C release in incubation were measured throughout both growing seasons. Application of 11.5 Mg ha-1 of PHC resulted in the highest enzymatic activities and MBC, representing a mean in crease of respectively 30 and 55% over the control. Addition of MF to PHC resulted in a greater increase in enzyme activities (12–18%) than PHC alone but had little effect on MBC. Generally, enzyme activities and MBC decreased in the second season. The carbon mineralization potential was low, indicating that the composted material was relatively stable. The addition of 11.5 Mg PHC ha-1 produced the highest marketable potato tuber yield with (34 Mg ha-1) or without (27 Mg ha-1) fertilizer supplement, whereas the highest wheat grain yield was obtained with the 23 Mg PHC ha-1 level in the following season. When PHC was added at 11.5 Mg ha-1, it markedly improved soil biochemical properties and potato crop yield whereas the 34.5 Mg ha-1 level was excessive. Key words: Papermill, farm manure, compost, enzyme activity, microbial biomass

Modeling the role of papermill sludge in the organic carbon cycle of paper products

Fundamental information about the chemistry of sludge, published rates of sludge generation, and models of paper production and wastepaper recycling were combined to create a predictive model. The goal of the modeling exercise was to determine and project global sludge production until the year 2050. It was predicted that a global shift in paper and paperboard production would result in the Asia-Pacific region emerging as a major producer of papermill sludge. Global production of papermill sludge was predicted to rise over the next 50 years by between 48 and 86% over current levels. Sludge was found to contain a large amount of woody organic material, but the proportion of this material in the sludge was found to drop as recycling programs were implemented. Sludge was also found to contain a large amount of woody carbon, which comprised about 30% of the total sludge solids. The presence of such a large proportion of woody carbon may become important if a system of carbon crediting is implemented for the forest industry. Key words: carbon cycle, forests, papermill sludge, modeling, life cycle analysis.

Improvement of soil properties and fruit yield of native lowbush blueberry by papermill sludge addition

Combined primary and secondary papermill sludge (PS) is a good potential source of C and other nutrients to restore low organic matter sandy soils supporting native lowbush blueberry (Vaccinium angustifolium Ait.). A 3-yr field study was conducted to compare the effect of PS with mineral fertilizers (MF) on the blueberry yield and soil chemical properties and enzyme activities of a l’Afrique sand (Humo-Ferric Podzol) in the Saguenay-Lac Saint-Jean area (Quebec, Canada). The PS was applied in the spring of the sprout year at 0, 8.5, 17 and 34 Mg ha-1 and MF was applied at 0, 13, 26 and 52 kg N ha-1. The highest fresh fruit yields were obtained at 8.5 and 17 Mg PS ha-1. The 34 Mg PS ha-1 treatment produced berry yield comparable to the control. This PS rate reduced pH, but increased inorganic N, Mehlich-3 extractable P and Mn in the 0- to 15-cm soil layer. The NO3−-N content of the 15- to 30-cm and 30- to 60-cm soil layers was also increased by PS, suggesting leaching. The MF significantly affected soil inorganic N content only at 3 wk after its application in the first year. The PS rate linearly increased the soil acid phosphatase activity in the first year. The arylsulfatase activity was also higher in PS than in MF treatment, but was severely depressed by 34 Mg PS ha-1 in the last 2 yr. This study indicated that PS, when used at low rates, improves lowbush blueberry yield and the soil enzyme activity on this low fertility sand. Key words: Papermill sludge, lowbush blueberry, soil composition, soil enzyme

Combined primary/secondary papermill sludge as a nitrogen source in a cabbage-sweet corn cropping sequence

Combined primary/secondary papermill sludge (PS) is rich in N and may potentially be used as a N source for horticultural crops. A 3-yr experiment was conducted to determine the effects of PS application on crop yields, N uptake and N recovery. The PS was applied in 1996 on a Bedford silty clay (Humic Gleysol) cropped to winter cabbage (Brassica oleracea var capitata L. 'Bartolo') at 0, 8, 16, 32, and 64 Mg ha-1 (dry basis). In 1997, PS was applied at 44% of the 1996 rates to the same plots and cropped to sweet corn (Zea mays L. 'Delectable'). No PS was applied in 1998 to evaluate residual effects on corn. Treatments with ammonium nitrate (AN) at 50, 100 and 200% of N fertiliser recommendations were included each year as a reference for crop response. The PS had a C:N ratio of 42:1 in 1996 and of 28:1 in 1997. About 29% of the total N in PS was inorganic. Cabbage and corn marketable yields and N uptake increased with increasing amounts of PS applied. AN supplemented with PS further increased cabbage yields. Based on the N fertiliser replacement value, the N efficiency coefficient of PS was 44% in the first year. A N residual effect of the PS applied in 1996 was observed on the corn yield in 1997. The two PS applications also had a very significant residual effect on corn yield in the third year, although supplemental AN at 150 kg N ha-1 tended to further increase yields. The apparent total N recovery by the three crops was similar for PS and AN (i.e., 34 vs. 38%). The apparent recovery of organic N from PS decreased with increasing rates of application from 46 to 25%. These results suggest that PS is an effective source of N for crops and that significant residual N effects should be considered when estimating the N needs of subsequent crops. Key words: Cabbage, nitrogen, mineralization coefficient, paper mill residues, sweet corn