Mechanisms governing the leaching of soil metals as a result of disposal of olive mill wastewater on agricultural soils.

Olive mill wastewater (OMWW) is an acidic, saline, and organic matter-rich aqueous byproduct of olive oil production that is usually disposed of by spreading on agricultural soils. This study tested whether spreading OMWW can release indigenous soil metals (Fe, Mn, Cu and Zn) through pH, redox, and DOM complexation-related mechanisms, using three agricultural soils having different textures and chemical properties, and controlled pH and redox conditions (pH5.6 or 8.4; ORP from -200 to +250mV). Comparison treatments included a solution having the same salt content and composition as OMWW but lacking OM, and deionized water (DW). In all three soils and under all pH and redox conditions, the model salt solution and DW treatments solubilized considerably fewer metal cations than did OMWW. Overall, the primary factor in metals release from the soils by OMWW was the DOM fraction. pH, redox and soil type played secondary but important roles in solubilization of the various metals. pH had a major impact on Mn leaching but no impact on Fe and Cu leaching. Conversely, redox did not affect Mn leaching, but lower redox conditions contributed to elevated release of both Fe and Cu. For the most part, released metals were sourced from water soluble, exchangeable, easily reducible, and moderately reducible soil metals pools. Fe, Mn and Cu released from the soils by OMWW featured mainly as metal-organic complexes, and OMWW generally caused Zn precipitation in the soils. Soils rich in clay and organic matter under reduced pH and low redox conditions released substantially more metal cations than did a sand-rich soil. Spreading OMWW may result in sequestration of essential micronutrients like Zn, and increased availability of other micronutrients such as Fe, Mn and Cu.

Using polyethylene sleeves with forced aeration for composting olive mill wastewater pre-absorbed by vegetative waste.

Composting in closed polyethylene sleeves with forced aeration may minimize odor emissions, vectors attraction and leachates associated with open windrows. The present study demonstrates the use of this system for composting olive mill wastewater (OMW), the undesired stream associated with the olive milling industry. A polyethylene sleeve of 1.5-m diameter and ca. 20-m long was packed with shredded municipal green waste which was pre-soaked in OMW for 72 h. Process conditions were controlled by means of a programmable logic controller (PLC) equipped with temperature and oxygen sensors. Thermophilic temperatures (>45 °C) were maintained for one month followed by temperatures in the range of 30-40 °C, ca. 20 °C above ambient temperature, for a period of 3.5 months. Oxygen levels were controlled and the system was kept aerobic. Water content gradually decreased with sufficient levels for efficient composting. The finished compost was non-phytotoxic to Cress (Lepidium sativum L.) in a lab bioassay. It was also found suitable as an ingredient in peat, tuff, and coir based growing media, evaluated by plant growth tests with basil and ornamental plants. The viability of this approach for disposing off OMW is much dependent on the liquid absorption capacity of the vegetative waste.

A flexible control system designed for lab-scale simulations and optimization of composting processes.

Understanding and optimization of composting processes can benefit from the use of controlled simulators of various scales. The Agricultural Research Organization Composting Simulator (ARO-CS) was recently built and it is flexibly automated by means of a programmable logic controller (PLC). Temperature, carbon dioxide, oxygen and airflow are monitored and controlled in seven 9-l reactors that are mounted into separate 80-l water baths. The PLC program includes three basic heating modes (pre-determined temperature profile, temperature-feedback ("self-heating"), and carbon dioxide-dependent temperature), three basic aeration modes (airflow dependence on temperature, carbon dioxide, or oxygen) and enables all possible combinations among them. This unique high flexibility provides a robust and valuable research tool to explore a wide range of research questions related to the science and engineering of composting. In this article the logic and flexibility of the control system is presented and demonstrated and its potential applications are discussed.

Composting municipal biosolids in polyethylene sleeves with forced aeration: Process control, air emissions, sanitary and agronomic aspects.

Composting in polyethylene sleeves with forced aeration may minimize odor emissions, vectors attraction and leachates associated with open windrows. A disadvantage of this technology is the lack of mixing during composting, potentially leading to non-uniform products. In two pilot experiments using biosolids and green waste (1:1; v:v), thermophilic conditions (>45°C) were maintained for two months, with successful control of oxygen levels and sufficient moisture. Emitted odors declined from 1.5-3.8×105 to 5.9×103-2.3×104 odor units m-3-air in the first 3weeks of the process, emphasizing the need of odor control primarily during this period. Therefore, composting might be managed in two phases: (i) a closed sleeve for 6-8weeks during which the odor is treated; (ii) an open pile (odor control is not necessary). Reduction of salmonella, E. coli and coliforms was effective initially, meeting the standards of "Class A" biosolids; however, total and fecal coliforms density increased after opening the second sleeve and exceeded the standard of 1000 most probable number (MPN) per g dry matter. Compost maturity was achieved in the open piles following the two sleeves and the final compost was non-phytotoxic and beneficial as a soil additive.

Impact of spreading olive mill waste water on agricultural soils for leaching of metal micronutrients and cations.

Olive mill waste water (OMWW) is an acidic (pH 4-5), saline (EC âˆ¼ 5-10 mS cm-1), blackish-red aqueous byproduct of the three phase olive oil production process, with a high chemical oxygen demand (COD) of up to 220,000 mg L-1. OMWW is conventionally disposed of by uncontrolled dumping into the environment or by semi-controlled spreading on agricultural soils. It was hypothesized that spreading such liquids on agricultural soils could result in the release and mobilization of indigenous soil metals. The effect of OMWW spreading on leaching of metal cations (Na, K, Mg, Mn, Fe, Cu, Zn) was tested in four non-contaminated agricultural soils having different textures (sand, clay loam, clay, and loam) and chemical properties. While the OMWW contributed metals to the soil solution, it also mobilized indigenous soil metals as a function of soil clay content, cation exchange capacity (CEC), and soil pH-buffer capacity. Leaching of soil-originated metals from the sandy soil was substantially greater than from the loam and clay soils, while the clay loam was enriched with metals derived from the OMWW. These trends were attributed to cation exchange and organic-metal complex formation. The organic matter fraction of OMWW forms complexes with metal cations; these complexes may be mobile or precipitate, depending on the soil chemical and physical environment.

Soil spreading of liquid olive mill processing wastes impacts leaching of adsorbed terbuthylazine.

Olive mill waste water (OMWW) is a major byproduct of the three phase olive oil production process. OMWW has high acidity (pH âˆ¼ 4-5), high salt content (EC âˆ¼ 5-10 mS cm(-1)), extremely high biological and chemical oxygen demand (BOD and COD up to 100,000 and 220,000 mg L(-1), respectively), and also high concentrations of organic compounds such as phenols and polyphenols. As a result, OMWW cannot be freely discharged into domestic wastewater treatment plants, but on-site treatment is very expensive and not sufficiently effective. Uses for OMWW such as agricultural recycling and co-composting were found to be impractical or expensive. Thus, OMWW is frequently spread on agricultural land for disposal. However, excessive or uncontrolled spreading of such organic-rich and saline wastewater could have many deleterious effects on soil quality, including salinization, phytotoxicity, or contaminant movement. The impact of OMWW on the leaching of adsorbed terbuthylazine, a soil-applied herbicide, was tested in four soils of varying physical and chemical properties. Although terbuthylazine solubility in OMWW is significantly higher than in water, leaching of adsorbed terbuthylazine from OMWW-treated soils was less than from control treatments. Low soil organic carbon and clay contents were major factors that contributed to reduced terbuthylazine leaching after soil treatment with OMWW.

Effects of harvest date, irrigation level, cultivar type and fruit water content on olive mill wastewater generated by a laboratory scale 'Abencor' milling system.

Olive mill wastewaters (OMW) were obtained at laboratory scale by milling olives from four cultivars grown at different irrigation levels and harvested at different times. Samples were compared based on wastewater quantity, pH, suspended matter, salinity, organic load, total phenols, NPK, and phytotoxicity. Principal component analysis discriminated between harvest times, regardless of olive cultivar, indicating substantial influence of fruit ripeness on OMW characteristics. OMW properties were affected both by the composition and the extraction efficiency of fruit water. As the fruit water content increased, the concentrations of solutes in the fruit water decreased, but the original fruit water composed a larger portion of the total wastewater volume. These contradicting effects resulted in lack of correlation between fruit water content and OMW properties. The significant effects shown for fruit ripeness, irrigation and cultivar on OMW characteristics indicate that olive horticultural conditions should be considered in future OMW management.

Co-composting of solid and liquid olive mill wastes: management aspects and the horticultural value of the resulting composts.

Successful co-composting of solid and liquid olive mill wastes (OMW) and obtaining a product of horticultural value may increase the viability of this recycling approach. Two composting cycles were performed, in which olive mill solid wastes (OMSW) were used to form five mixtures, wetted either with fresh water or with olive mill wastewater (OMWW). Up to approximately 0.3m(3) of OMWW could be applied to each m(3) of the raw materials without negatively affecting the chemical, physical and horticultural properties of the resulted composts. A growing media composed of perlite amended with 25-33% OMW-composts showed higher suppressiveness against Fusarium oxysporum f. sp. melonis as compared to equivalent perlite:peat moss mixtures. The yields of tomato plants grown in peat moss amended with 20% (v:v) of OMW-composts were not significantly different than plants grown in unamended peat. The viability of co-composting as a treatment approach for OMWW is discussed in the context of management aspects and the horticultural value of the final product.

The flow rate of whole and submandibular/sublingual gland saliva in patients receiving replacement complete dentures.

Provision of complete dentures to a new denture wearer increases the salivary flow rate is well known. The new dentures act as an additional mechanical stimulus to the salivary reflexes, thus increasing the flow rate. The purpose of this study was to determine whether replacing complete dentures would elicit the same response. Unstimulated and stimulated whole and submandibular/sublingual (SM/SL) saliva were collected before inserting complete replacement dentures and again after 2 days and after 3 weeks of denture wearing. Unstimulated whole salivary flow rate increased significantly 2 days after inserting replacement dentures, decreasing at 3 weeks but remaining significantly above the baseline. Stimulated whole salivary flow rate increased significantly after 2 days but decreased to normal after 3 weeks. Stimulated and unstimulated SM/SL salivary flow rate increased significantly after 2 days, decreasing at 3 weeks while remaining significantly above the values found before denture insertion.

Cosmetic or esthetic dentistry?

This article, through presentation of case studies, defines differences and suggests separate definitions for the terms cosmetic dentistry and esthetic dentistry. Dentistry strives to emulate harmonious form and function for therapy, and modification of appearance is an integral part of dental treatment. Cosmetic dentistry suggests a certain accommodation and is a compromise of current technology. Cosmetic dentistry is commonly selected as an interim procedure that does not necessarily function ideally and does not always emulate the pristine state of a natural dentition. Esthetic dentistry requires less accommodation, incorporates acceptable biologic technology for long-term survival, functions suitably, and mimics the pristine state of the natural dentition. Cosmetic and esthetic dentistry are different in definition, concept, and execution.

The right of dentists to take extra precautions when treating patients known to carry the human immunodeficiency virus.

Oral health care providers have taken various positions toward the concept of correct behavior toward and management of patients who are seropositive for human immunodeficiency virus. Several tribunal judgments and articles have discussed and analyzed this subject. This article presents a new detailed report and analysis and decision issued by a dental profession panel (tribunal) in Ontario, Canada. The concepts of universal precautions and antidiscriminatory acts are discussed.

Clinical characteristics and treatment of patients with oral lichen planus in Israel.

Oral lichen planus (OLP) has a multiple-site involvement, with the buccal mucosa being the most prevalent. A possible relationship between OLP and the risk of malignancies in the involved site is documented. The characteristics of OLP have been studied in different populations; however, no similar studies have been conducted in any Jewish population. The purpose of this study was to evaluate the natural history of OLP in Israeli Jewish patients. Data were collected from 157 charts of patients with histologically confirmed OLP. No evidence suggesting a connection between OLP and diabetes, cardiovascular disease, smoking, alcohol use, or positive Candida culture was found. Skin involvement of lichen planus was found in one fifth of the patients. Symptomatic OLP was noted in half of the patients, mainly in those with the erosive form. In 65% of the patients with symptoms, improvement by more than 50% was shown within 2 weeks of steroid use. The transformation rate of 1.3% of OLP into malignancy was observed in the entire group. A constant follow-up for contributing symptoms and for early diagnosis of suspected transformed lesions is of utmost importance.

Fourth molars: a clinical study.

Supernumerary teeth may be found in both the primary and permanent dentition, although they are more common in the permanent dentition. Presence of a fourth molar is rare, and such a tooth is almost invariably impacted. Dental practitioners should be aware of the possibility of encountering this rare supernumerary, its diagnosis and treatment. The authors of this article conducted a survey of patients in Montreal, looking specifically at the prevalence, aetiology, diagnosis, pathology and treatment of fourth molars. Their findings are reported here, and compared with data from the literature over the past 15 years.

Dental caries and sugar consumption into the 21st century.

New trends towards the effect and role of sugar consumption in the etiology of dental caries into the 21st century are presented, analyzed and discussed. Many factors such as the amount of sugar consumed, the frequency of sugar intake and the kind of sugars ingested have to be taken into consideration. Over the years, the relative importance of these factors has changed. For a very long time, sugar has been "blamed" as a primary etiological factor in the development of dental caries. However, a number of recent reports have attributed a much less important role to carbohydrates. Sugar consumption only does not affect caries prevalence as much as it used to. It is obvious that the role of sugar in the etiology of caries must be reviewed. Additional factors like overall nutrition, the number of meals and snacks per day, education and motivation, fluoride (in tablets or drops, in mouthwashes, toothpastes, baby foods, formulas, beverages, milk, vitamin supplements and/or fluoridated water ingested), socioeconomic group, ethnicity, oral hygiene status, use of preventive methods and sweeteners other than sucrose are presented.

Implant-supported overdenture rehabilitation and progressive systemic sclerosis.

Progressive systemic sclerosis, or systemic scleroderma, is an autoimmune multisystemic disease associated with vascular abnormalities, connective tissue sclerosis, atrophy, and autoimmune changes. The complex oral problems that may develop in patients with the disease and the difficult oral access necessitate extreme care in preventing dental disease. The oral management of a patient with an edentulous mandible and progressive systemic sclerosis, using an overdenture supported by osseointegrated implants, is presented and discussed.

Prevalence of torus palatinus in a population of young and adult Israelis.

The prevalence of torus palatinus, a common exostosis with a debatable pathogenesis, was epidemiologically investigated in a group of 1002 Israeli Jews. This protuberance was observed in 21% of the entire sample, with non-significant differences among different age groups. The smooth type of torus was noted in 72.9%, 68.1% were smaller than 2 cm, and 53.8% were located in the molar area only. The prevalence of torus palatinus in the combined molar-premolar area increased with age, whereas in the molar area it decreased, expressing a significant relation between location and age (p < 0.01). The prevalence of tori larger than 2 cm was much higher in the 21-year and older age groups than in the younger groups. The diverse prevalence of torus palatinus in some of the ethnic groups was also statistically significant (p < 0.05). The aetiology of this common osseous outgrowth is probably multifactorial, including environmental factors acting in a complicated and unclear interplay with genetic factors.

Candidal infection of the tongue together with candidal infection of the palate in patients with the human immunodeficiency virus.

The most common oral opportunistic infection affecting persons with acquired immunodeficiency is candidiasis. This article reports on candidal infection of the tongue together with candidal infection of the palate in patients who have the human immunodeficiency virus. A retrospective analysis of 336 patients with acquired immunodeficiency syndrome revealed a prevalence of 8% with candidal infection of both the tongue and palate. Patients in this group were significantly older (39.2 years versus 34.5 years) and had significantly lower CD4-CD8 ratios than did the rest of the cohort.