Alan P. Newman

Characterization of activated carbon prepared from a single cultivar of Jordanian olive stones by chemical and physicochemical techniques

Abstract The yearly production of olives in Jordan is more than 100 kton of which a significant proportion is de-stoned prior to sale. In this work, olive stones from Jordan were used for the preparation of activated carbon with the aim of producing a water treatment product suitable for treatment of contaminated groundwater. The preparation conditions were varied to study their effects on the surface area, porosity, morphology, functionality and crystal structure. Variables studied included time of carbonization, time of activation, activating agent, particle size, sample pre-drying, hydrogen peroxide post treatment and the effect of the activation process itself. X-ray diffraction analysis showed that the prepared activated carbon is essentially amorphous and indicated the presence of traces of oxides of calcium and magnesium, while infrared spectroscopy showed peaks relating to hydroxyl, aliphatic, ether, aromatic and phenolic groups. These functional groups and crystals may have some effect(s), i.e. catalytic, if the products were to be used in any reaction for water treatment. Nitrogen adsorption was used for the determination of apparent surface area and pore size distribution. Results showed that the active carbon is of moderate surface area and micropore volume is over 80% of the total pore volume. Scanning electron microscopy showed the development of the pores during different treatments. The most noticeable effect on the texture was that when the sample was not pre-dried. The adsorption capacity and surface acidity/basicity of all the samples have been studied by methylene blue (MB) adsorption method and partial Boehm titrations, respectively. Results showed that the surface is mainly of basic nature, and also indicated that MB was adsorbed following the pore filling mechanism. Hydrogen peroxide post-treatment produced reduced surface area measurements.

Biodegradation and microbial diversity within permeable pavements

Permeable Pavement Structures (PPS), designed to improve drainage of urban paved areas, have been demonstrated to function as hydrocarbon traps with 98.7% efficiency and as powerful in-situ aerobic bioreactors. A mesocosm constructed like one of these pavements and inoculated with microorganisms with the aim of increasing hydrocarbon biodegradation was found not to retain a viable population of organisms derived from the inoculum, although the protozoan fauna initially increased in diversity more quickly than in an identical non-inoculated mesocosm. The source of protozoan diversity in oil cultures containing different components used in pavement construction, was revealed to be primarily the granite sub-base which contained flagellates, gymnamoebae, ciliates and testate amoebae. Other components only provided cosmopolitan genera such as Colpoda and Heteromita. Biodegradation was facilitated to a similar degree by bacteria or fungi, as demonstrated by inhibition with tetracycline and cycloheximide, respectively. A full microbial community, without inhibition by antibiotics, degraded the greatest mass of oil. Elucidating the role of protozoa assists in fully understanding and optimising the function of PPS in hydrocarbon degradation.

Protecting groundwater with oil-retaining pervious pavements: historical perspectives, limitations and recent developments

Pervious pavements are important systems used for source control in Sustainable Drainage Systems (SuDS), which allow water to infiltrate into hard surfaces and then slowly release it either to a drainage outlet or into the ground. They also remove low levels of pollution from the water by filtration and also by biodegradation of hydrocarbons, which are adsorbed to materials within the construction. Following a historical overview of research in this area, this paper describes an experiment that demonstrates the importance of the choice of geotextile in the retention of day-to-day emissions of oil from parked vehicles and the development and initial trials of an oil interceptor system, which has been incorporated within pervious surface construction. The results indicated that in the early years of the life of a pervious pavement the choice of geotextile has a vitally important impact on its oil-retaining role but that, after several years of silting, the choice may become less important. The results also demonstrated that modified direct infiltration pervious pavement systems, constructed on site from traditional materials and geomembrane, can effectively contain very large hydrocarbon spills.

Stormwater harvesting for irrigation purposes: An investigation of chemical quality of water recycled in pervious pavement system

Most available water resources in the world are used for agricultural irrigation. Whilst this level of water use is expected to increase due to rising world population and land use, available water resources are expected to become limited due to climate change and uneven rainfall distribution. Recycled stormwater has the potential to be used as an alternative source of irrigation water and part of sustainable water management strategy. This paper reports on a study to investigate whether a sustainable urban drainage system (SUDS) technique, known as the pervious pavements system (PPS) has the capability to recycle water that meets irrigation water quality standard. Furthermore, the experiment provided information on the impact of hydrocarbon (which was applied to simulate oil dripping from parked vehicles onto PPS), leaching of nutrients from different layers of the PPS and effects of nutrients (applied to enhance bioremediation) on the stormwater recycling efficiency of the PPS. A weekly dose of 6.23 × 10(-3) L of lubricating oil and single dose of 17.06 g of polymer coated controlled-release fertilizer granules were applied to the series of 710 mm × 360 mm model pervious pavement structure except the controls. Rainfall intensity of 7.4 mm/h was applied to the test models at the rate of 3 events per week. Analysis of the recycled water showed that PPS has the capability to recycle stormwater to a quality that meets the chemical standards for use in agricultural irrigation irrespective of the type of sub-base used. There is a potential benefit of nutrient availability in recycled water for plants, but care should be taken not to dispose of this water in natural water courses as it might result in eutrophication problems.

Microbial Ecology of Oil Degrading Porous Pavement Structures

The microbial ecology of any biodegradation system is the fundamental factor that controls both the effectiveness of the ongoing biodegradation process and also the ability of the biodegrading population to maintain stability at times of environmental stress. Studies are reported here which provide both initial information on the ecology of an oil degrading porous pavement system (PPS) and significantly advances our knowledge on the appropriate techniques to study that ecology. A major step forward has been made in the use of molecular biological techniques to quantify bacterial biodiversity and these techniques have shown for the first time the extent to which, despite the fact that a single carbon source is available, the complexity of the microbial population in a model structure increases with time. In fact, the initial commercial inoculum used is totally replaced by a bacterial population selected for the conditions in the structure. The importance of the protozoan population and source of its inoculum is also demonstrated.

The Use of Activated Carbons with Basic Properties for the Treatment of 2-Chlorophenol

A range of basic activated carbons was prepared from single cultivar Jordanian olive stones and their chemical composition, textural properties and surface groups investigated. One of the samples was de-ashed and then oxidized using concentrated nitric acid to study the effects of inorganic content and surface oxidation on its adsorption capacity towards 2-chlorophenol (2-CP). Commercial samples with combined acidic and basic properties were also tested with respect to 2-CP adsorption. An attempt was made to correlate the total basicity with the adsorption constants of the Langmuir equation and with other properties. These properties included burn-off, apparent surface area, micropore volume, total pore volume and Methylene Blue (MB) adsorption surface area. The total basicity had no relationship with any adsorption parameter. However, total basicity was found to have a relationship with the total pore volume, the micropore volume, MB adsorption and burn-off. The BET surface area showed only a very weak relationship with the total basicity. Burn-off had a relationship with the relative affinity of the adsorbate and the surface and Langmuir constants, but not with the adsorption capacity. De-ashing the sample using HF/HCl decreased the total basicity and MB adsorption but increased the total acidity and the capacity towards 2-CP uptake. The mineral contents of both prepared and commercial samples were analyzed and found to play no role in the adsorption of 2-CP.

Design and Validation of a Test Rig to Simulate High Rainfall Events for Infiltration Studies of Permeable Pavement Systems

This paper presents the design and validation of a relatively cost-effective test rig to simulate high rainfall events; such a rig offers a great opportunity for conducting studies (e.g., high infiltration studies) that require high intensity of rainfall on pervious pavements and other permeable systems. The calibration of the test rig, which produced more than 600 mm/h rainfall intensity, was successful. A simple method of using digital photography to capture raindrops and determine raindrop diameter was developed and used successfully to determine the drop size of simulated rainfall by the test rig. Results obtained by this method indicated that the raindrop diameter varied from 0.69–8.97 mm, which was consistent with the high rainfall intensity generated by test rig. Categorization of raindrop size according to Wilson Bentley’s classification showed 1.84, 6.42, 33.95, 26.61, and 31.19% for very small, small, medium, large, and very large drops, respectively, which was considered consistent with the relatively high rainfall intensity generated by the test rig.

Evaluation of the effectiveness of wrapping filter drain pipes in geotextile for pollution prevention in response to relatively large oil releases

French drains or infiltrating filter drains are commonly fitted with slotted plastic pipe to act as an overflow mechanism when rainfall is too great to allow complete infiltration. The release of the effluent from such pipes is commonly to surface water courses. Whilst there is expected to be some slight degree of protection against hydrocarbon release because of interaction with the drain’s stone infill material this will be severely limited. This paper reports an experiment in which model filter drains with or without geotextile sleeves around the slotted drain are challenged with lubricating oil. The textile was a surface-treated non-woven geotextile manufactured from polyester. The models were challenged with very high loadings of oil, as would be anticipated in a motor vehicle collision occurring close to the drain. A series of simulated 10-20mm rain events over 1 hour were applied and two sample types were collected which either included or excluded any free product. Additional aliquots of oil were added at each rain event. The un-sleeved models were found to release visible free product with the addition of as little as 100ml of oil per linear meter of drain. For the models with geotextile sleeves there was no such release with as much as 2000ml per linear metre. Analysis showed that under these conditions the geotextile sleeved pipes continued to produce effluent with hydrocarbon concentrations well below the 5000μg/l limit usually accepted in the UK.

Performance of an enhanced pervious pavement system loaded with large volumes of hydrocarbons

Five litres of lubricating oil and two 8.5 litre batches of diesel were deposited on each of two hydraulically isolated experimental enhanced pervious pavement parking bays. The 50 mm aggregate subbases of the two bays were of either recycled concrete or crushed limestone. The bays were constructed in such a way that a near-surface gravity separator was created by the arranging of the outlet pipes such that a permanent pool of water was maintained in the system and water could only enter from below the level of any floating oil. Dissolved/dispersed hydrocarbons were measured at acceptable concentrations when monitoring was carried out over a period of approximately 5 months. The maximum concentration was 7.2 mg/l and of all the samples collected only 3% exceeded the 5 mg/l limit applied in the UK for a class 1 interceptor, and the majority of samples had hydrocarbon concentrations of less than 2 mg/l. Much more significant is the fact that no free product was discharged from either system up to the time the experiment was dismantled 2 years from the first oil application despite the fact that sufficient hydrocarbon had been added to each pavement to produce a film on a water surface of over 500 hectares.

An assessment of the potential use of compost filled plastic void forming units to serve as vents on historic landfills and related sites

Much of the solid municipal waste generated by society is sent to landfill, where biodegrading processes result in the release of methane, a major contributor to climate change. This work examined the possibility of installing a type of biofilter within paved areas of the landfill site, making use of modified pervious paving, both to allow the escape of ground gas and to avoid contamination of groundwater, using specially designed test models with provision for gas sampling in various chambers. It proposes the incorporation of an active layer within a void forming box with a view to making dual use of the pervious pavement to provide both a drainage feature and a ground gas vent, whilst providing an active layer for the oxidation of methane by microbial action. The methane removal was observed to have been effected by microbial oxidation and as such offers great promise as a method of methane removal to allow for development of landfills.