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PubMed2005

Solid waste collection and recycling in Nibong Tebal, Penang, Malaysia: a case study.

The implementation of a suitable solid waste management programme with appropriate methods of recycling as an inherent element is vital to the alleviation of the problems associated with solid waste generation, handling and disposal, environmental conservation, public hygiene, etc. The present work is a case study on solid waste collection and recycling practices in Nibong Tebal town, Penang, Malaysia. The amount and types of domestic waste generated, household participation in recycling, identification of existing problems related to the implementation of the recycling programme, etc. formed the basis of this study. Surveys (interviews/questionnaires) and on-site observations were conducted to gather information on the solid waste collection and recycling practice of the residents. A focus group of 60 individuals was selected and their response to a questionnaire, prepared according to a Likert scale, was obtained and analysed. The majority of the respondents expressed concerns about recycling and wanted more to be done in this regard. Illegal collection, aesthetically displeasing sites and a lack of public awareness were problems of major concern. Issues related to inadequate funding and manpower as well as end market are also addressed and suggestions made.

Cities↗
PubMed1991

Technology tradeoffs related to advanced mission waste processing.

Manned missions to the Moon and Mars will produce waste, both in liquid and solid form, from the day-to-day life-support functions of the mission--even considering a "closed" physico-chemical life support approach. An "open" life support system configuration, even one reliant on in situ resources, would result in even more waste being produced. The solution for short term missions appears to be either to store these wastes on-site or to convert them to useful products needed by other systems such as methane, water and gases which could be used for propulsion. The solution for longer term missions appears to be to incorporate their use within the life support system itself by making them a part of a closed ecological life-support system where nearly all materials are recycled. This paper discusses briefly the extent and impact of the life-support system waste production problem for a lunar base for different life support system configurations, including the impact of using in situ resources to meet life support requirements. It then discusses in more detail trade-offs among six of the currently funded physico-chemical waste processing technologies being considered for use in space.

Ammonia↗
PubMed1991

Processes for water reclamation.

Water treatments fall into two broad classes; those that remove or destroy specific classes of pollutants, i.e. color, metal ions, hardness, sediment, bacteria, etc., and those that remove water from nearly all of the pollutants. The first class includes sedimentation, biological treatment by microbes, chemical precipitation, adsorption on active carbon or ion exchange resins, and disinfection. The second class includes distillation, freezing and reverse osmosis (RO). The first class are the least expensive in terms of energy and have a long history of successful use on a large scale to reclaim water containing sewage. Most of the second group are energy intensive and have been used primarily on a moderate scale. All processes, except disinfection, leave a residual sludge or brine that contains a substantial quantity of water. Many of the problems of treating waste water for reuse on Earth stem from the fact that waste water carries pathogenic organisms from one location to another and may spread disease over long distances. In a closed group, such as in a Space Station, there are so many other routes for transfer of microorganisms, i.e. in the air, on surfaces, by hand-to-mouth, that undue emphasis on disinfection of water is inappropriate. Successful examples of water reuse on Earth are reviewed in terms of their possible application in space.

Carbon↗
PubMed1991

Performance characteristics of a low sludge bioreactor for wastewater treatment.

An immobilized microbial cell system was developed and tested for the treatment of industrial wastewater. A consortium of selected aerobic microorganisms was immobilized onto several different support matrices in a packed bed reactor configuration and operated in a continuous process mode. Comparison of the support matrices showed only small differences in treatment efficiency, but significant differences in sludge production and process stability. Porous polymer supports were highly resistant to feedstream upsets and produced 80% lower sludge solids as compared with non-porous supports. These results were seen at both the benchtop and pilot plant scale for treatment of complex industrial waste streams. This technology was applied, in preliminary experiments, to the treatment of a model waste stream simulating wastewater from a Controlled Ecological Life-Support System (CELSS).

Biofilms↗
PubMedDate not supplied

Sustainable land application: an overview.

Man has land-applied societal nonhazardous wastes for centuries as a means of disposal and to improve the soil via the recycling of nutrients and the addition of organic matter. Nonhazardous wastes include a vast array of materials, including manures, biosolids, composts, wastewater effluents, food-processing wastes, industrial by-products; these are collectively referred to herein as residuals. Because of economic restraints and environmental concerns about land-filling and incineration, interest in land application continues to grow. A major lesson that has been learned, however, is that the traditional definition of land application that emphasizes applying residuals to land in a manner that protects human and animal health, safeguards soil and water resources, and maintains long-term ecosystem quality is incomplete unless the earning of public trust in the practices is included. This overview provides an introduction to a subset of papers and posters presented at the conference, "Sustainable Land Application," held in Orlando, FL, in January 2004. The USEPA, USDA, and multiple national and state organizations with interest in, and/or responsibilities for, ensuring the sustainability of the practice sponsored the conference. The overriding conference objectives were to highlight significant developments in land treatment theory and practice, and to identify future research needs to address critical gaps in the knowledge base that must be addressed to ensure sustainable land application of residuals.

Animal Welfare↗
PubMed2006

Simultaneous treatment of sewage sludge and food waste by the unified high-rate anaerobic digestion system.

This study aimed to evaluate the performance of the unified high-rate anaerobic digestion (UHAD) system treating co-substrate of sewage sludge and food waste. A 24-hr operating sequence consisted of four steps including fill, react, settle, and draw. The effects of co-substrate and organic loading rate (OLR) on the performance were investigated to verify the system applicability. In each OLR, the UHAD system showed higher CH4 recovery (> 70%), CH4 yield (0.3 L CH4/g VSadded) and CH4 production rate (0.6 L CH4/L/d) than the control system. In the specific methanogenic activity (SMA) tests on thermophilic biomass of the UHAD system, the average SMA of acetate (102 mL CH4/gVSS/d) was much higher than those of butyrate (85 mL CH4/g SS/d) and propionate (42 mL CH4/gVSS/d). It was demonstrated that the UHAD system for co-digestion resulted in higher methane yield and methane production rate due to sequencing batch operation, thermophilic digestion, and co-digestion. The enhanced performance could be attributed to longer retention time of active biomass, faster hydrolysis, higher CH4 conversion rate, and balanced nutrient conditions of co-substrate in the UHAD system. Consequently, this optimized unification could be a viable option for the simultaneous treatment of two types of OFMSW with high stability.

Anaerobiosis↗
PubMed2006

Effective sludge solubilization treatment by simultaneous use of ultrasonic and electrochemical processes.

Sludge disintegration treatment by using simultaneously ultrasonic irradiation and electrolysis was investigated experimentally. A lab-scale diaphragm cell irradiated with ultrasound at a constant oscillating frequency of 20 kHz was used as a reactor. The batch experiments were carried out under different conditions of electric outputs of the ultrasonic generator, electric current for the electrolysis and different initial SS concentrations. A simultaneous treatment in the cathodic compartment without any chemical doses considerably facilitated the sludge solubilization, compared to the sonication alone. An increase in the electric current up to 400 mA under a constant ultrasonic density decreased the specific energy by 55% within the experimental range. The specific energy consumption was also reduced when the initial SS concentration increased. In addition, before carrying out the simultaneous treatment, a brief electrolysis was effective for further reduction of the specific energy and the acceleration of soluble COD generation.

Electrochemistry↗
PubMed2006

Improvement of wastewater treatment performance of the Fukashiba treatment plant.

The Fukashiba Treatment Plant Kashima Rinkai Specified Sewage Works has received wastewater from the petrochemical complex (90%) and public sewage of Kamisu and Hasaki town (10%). For this reason, the plant is facing many difficulties in producing good quality effluent. In order to solve these difficulties, we are reviewing the treatment performance and making efforts for its improvement with nitrification inhibition, control of bio-persistent substances and the PRTR approach.

Biodegradation, Environmental↗
PubMed2006

Electrolytic degradation of biorefractory organics and ammonia in leachate from bioreactor landfill.

Electrochemical oxidation was applied to treat the effluent from bioreactor landfill with leachate recirculation, characterised as poor biodegradability and high NH3-N concentration. In this study, the effluent was electrolysed in a batch reactor with Ti/TiO2-IrO2-RuO2 anode and stainless steel cathode. The oxidation of dissolved organic matter (DOM) during electrolysis was evaluated based on the evolution of molecular weight grade, hydrophilic fractionation (humic acid, fulvic acid and hydrophilic fractions), specific ultraviolet absorbance (SUVA254) and AOX. The impact of the initial NH3-N concentration on the oxidation was discussed. The results showed that at a current density of 100 mA/cm2, electrolysis time of 1.5 h and electrode gap of 1 cm, NH3-N with an initial concentration of 1.2 g/L could be completely eliminated and 56% of COD with an initial concentration of 1.2 g/L could be removed, which illustrated that the electrolysis-produced chlorine preferentially oxidised ammonia. The electrolysis mainly resulted in the degradation of humic substances and other high molecular DOM, followed by the increase of BOD/COD ratio and decline of SUVA254 of the leachate. The current efficiencies for COD and ammonia oxidation gradually decreased during the electrolysis, with the latter obviously higher than the former. At the optimal electrolysis time of 1.5 h, NH3-N could be totally removed and the BOD/COD ratio could be enhanced to 0.3, which was also favourable to control the AOX at a reasonable level.

Ammonia↗
PubMed2006

Quantification of sewer leakage: a review.

One of the goals of the APUSS project (assessing infiltration and exfiltration on the performance of urban sewer systems) is to assess sewer exfiltration, in order to support cities and operators to define problem-oriented rehabilitation strategies. In this paper, we review various methods currently used for the estimation of exfiltration and discuss data needs and applicability for rehabilitation planning. Although each approach has its individual advantages and drawbacks, we identified pressure tests and tracer methods to have the highest potential for decision support in rehabilitation planning. With regard to future challenges (e.g., micropollutants) such methods might play a key role in integrated sewer management.

Drainage, Sanitary↗
PubMed2006

Integrated modelling of two xenobiotic organic compounds.

This paper presents a dynamic mathematical model that describes the fate and transport of two selected xenobiotic organic compounds (XOCs) in a simplified representation of an integrated urban wastewater system. A simulation study, where the xenobiotics bisphenol A and pyrene are used as reference compounds, is carried out. Sorption and specific biological degradation processes are integrated with standardised water process models to model the fate of both compounds. Simulated mass flows of the two compounds during one dry weather day and one wet weather day are compared for realistic influent flow rate and concentration profiles. The wet weather day induces resuspension of stored sediments, which increases the pollutant load on the downstream system. The potential of the model to elucidate important phenomena related to origin and fate of the model compounds is demonstrated.

Benzhydryl Compounds↗
PubMed2006

Bench- and pilot-scale sludge electrodewatering in a diaphragm filter press.

Electrodewatering is a technique in which pressure dewatering is combined with electrokinetic effects to realize an improved solid/liquid separation and hence increased filter cake dry matter contents. In order to be energy efficient, it is shown that sludge should be dewatered by pressure dewatering to a high extent prior to electric field application, and a sufficient contact time for the electric field must be guaranteed. In order to realize these goals, a bench- and pilot-scale diaphragm filter press suited for electrodewatering were constructed for treatment of sewage and other types of sludges. It was shown that electrodewatering of sludge is a feasible technique, especially for biological sludge types. Other types of sludge are less suited for electrodewatering because of the restricted improvements that can be realized in cake dry matter content and the high electric energy consumption. Furthermore, it was shown in pilot-scale tests that the use of a diaphragm filter press with electrodewatering facilities was very well suited to deliver dry filter cakes of sewage sludge at a moderate energy consumption. Depending on local market prices for investment, operating and sludge disposal costs, this technology may therefore lead to important savings in the sludge management process.

Electrochemistry↗
PubMed2006

Effects of ferric hydroxide on methanogenesis from lipids and long-chain fatty acids in anaerobic digestion.

The addition of ferric hydroxide to sludge from a municipal anaerobic digester stimulated the rate of methanogenesis from canola oil when the initial oil concentration was high (4600 mg/L; P < 0.002), but not when it was low (920 mg/L; P > 0.05). Similar trends were observed when oleic acid, a fatty acid that is a major component of canola oil triglycerides, was provided, but the effects were statistically significant only when the initial concentration of ferric hydroxide was also high (18 g/L; P = 0.015). Iron reduction occurred when ferric hydroxide was added to microcosms containing anaerobic digester sludge, but the extent of ferrous iron production was much less in acetate-amended microcosms than in those that were provided with canola oil or oleic acid. Methanogenesis and acetate consumption were completely inhibited when the initial acetate concentration was approximately 5000 mg/L, regardless of the initial ferric hydroxide concentration. The main effect of ferric hydroxide in this system appears to have been a result of stimulation of the rate of fatty acid oxidation.

Anaerobiosis↗
PubMed2006

Anaerobic digestion of thermo-oxidized excess municipal sludge.

The effect of a thermo-oxidative co-treatment placed between the two reactors of two-stage anaerobic digestion of excess municipal sludge was studied. The oxidant used was hydrogen peroxide (H2O2), and moderate temperatures below the boiling point of water were considered. The first experiment was to elucidate the effect of two different temperatures (65 and 90 degrees C) of oxidation using a constant oxidant dose of 1.0 g H2O2/g influent volatile suspended solids (VSSinfluent). The use of thermo-oxidative co-treatment increased overall solids destruction by 24.9 and 33.5%, respectively, when operating at 65 and 90 degrees C, respectively. Because of this significant effect of temperature on the performance of the process, a second experiment was conducted using the higher temperature of 90 degrees C while decreasing the hydrogen peroxide dosage to 0.5, 0.25, and 0.1 g H2O2/g VSSinfluent. An increase in solids destruction of 13.9, 18.9, and 25.6% was observed when the thermo-oxidative co-treatment was used using oxidant dosages of 0.1, 0.25, and 0.5 g H2O2/g VSSinfluent, respectively.

Anaerobiosis↗
PubMed2006

Influence of staging, mean cell residence time, and thermophilic temperature on the thermophilic anaerobic digestion process.

As Class B biosolids land application has become less acceptable to many local jurisdictions, low-cost processes to achieve Class A standards have become more popular. Prominent among these low-cost processes is thermophilic anaerobic digestion. As a result, thermophilic anaerobic digestion is now a popular topic in wastewater treatment literature, but quantifiable methods for selecting a particular thermophilic process have not been offered. To provide for this need, an empirical model was developed from data collected in thermophilic anaerobic digestion studies conducted using East Bay Municipal Utility District's (Oakland, California) primary and waste activated sludge to feed both bench- and full-scale digesters. The model predicts at which thermophilic temperature and mean cell residence time (MCRT) one process will outperform or equal another, with respect to fecal coliform reduction. The different disinfection efficiencies in the different thermophilic processes might be explained by the presence or absence of high volatile acid and/or un-ionized ammonia levels in the processes' digested sludges. Data from these studies also show an apparent relationship between increased thermophilic temperatures and volatile solids destruction, and between increased temperatures and specific volatile acids production, for digesters operating at a 13-day MCRT and higher, but not for digesters operating at a 2-day MCRT.

Anaerobiosis↗
PubMed2006

Pretreatment of sludge with microwaves for pathogen destruction and improved anaerobic digestion performance.

A new way of generating Class A sludge using microwaves was evaluated through a series of laboratory-scale experiments. Microwaves provide rapid and uniform heating throughout the material. Other benefits of microwave treatment include instant and accurate control and selective and concentrated heating on materials, such as sludge, that have a high dielectric loss factor. Sludge was irradiated with 2450-MHz microwaves, and fecal coliforms were counted. Fecal coliforms were not detected at 65 degrees C for primary sludge and anaerobic digester sludge and at 85 degrees C for waste activated sludge when sludge was irradiated with 2450-MHz microwaves. During the bench-scale anaerobic digester operation, the highest average log reduction of fecal coliforms was achieved by the anaerobic digester fed with microwave-pretreated sludge (> or = 2.66 log removal). The anaerobic digester fed with microwave-irradiated sludge was more efficient in inactivation of fecal coliforms than the other two digesters fed with raw sludge and externally heated sludge, respectively. It took more than three hydraulic retention times for a bench-scale mesophilic anaerobic digester to meet Class A sludge requirements after feeding microwave-irradiated sludge. Class A sludge can be produced consistently with a continuously fed mesophilic anaerobic digester if sludge is pretreated with microwaves to reach 65 degrees C.

Anaerobiosis↗
PubMed2006

Effect of seeding materials and mixing strength on struvite precipitation.

Struvite precipitation has increasing interest as a technology for removing and recovering phosphorus from wastewater streams. Many chemical factors have been studied, such as optimum pH values and component-ion molar ratios, yet, understanding of physical aspects is lacking. Two physical parameters were tested: (1) seeding material addition and (2) mixing. Objectives were to evaluate three seeding materials and to optimize mixing conditions for struvite-crystal precipitation, growth, and subsequent sedimentation. Results confirm that mixing strength and proper seeding materials increase crystal size and improve settleability. For unseeded solutions, optimum phosphorus removal was achieved at a mixing strength of G = 76 s(-1). Struvite crystals that were added as the seeding material provided the best performance with respect to phosphorus removal and crystal-size distribution. Overall, this study provided information to improve the practical application of struvite precipitation as a phosphorous-treatment technology for wastewaters, while generating a marketable slow-release fertilizer as a product.

Animals↗