Sludge Transport Research Articles

Emptying, Transportation and Disposal of feacal sludge in informal settlements of Kampala Uganda: The economics of sanitation

Emptying, transportation and disposal of feacal sludge in informal settlements of Kampala Uganda is still a big challenge. With the use of semi-structured interviews, observation and review of secondary data, this study aims at identifying actors and factors determining emptying costs and the constraints limiting improved service provision. Individual private cesspool operators and Kampala City Council Authority (KCCA) on behalf of public services determine emptying charges. The main determining factors are: the capacity of the truck, fuel, distance, labor, dumping costs and profit margins of the cesspool truck operator and or the owner of the truck. The main constraints faced included limited number and poor maintenance of cesspool trucks, poor quality vacuum pumps and pipes, poor maintenance of pit latrines and customers' ignorance on the functionality of cesspool trucks. It is concluded that emptying prices are too high and a bottleneck to sludge removal. To influence emptying fees there is need to develop policies to regulate pricing, increase the number of cesspool trucks to stimulate competition, improve institutional capacity and encourage partnership, provide financial support and ensure that subsidies are 'tapped' by the rightful persons and sensitize the communities on the performance of cesspool trucks.

A new method of biological start-up in Arak activated sludge wastewater treatment plant

Starting up a wastewater treatment plant (WWTP) is one of the most important stages of operation. A new method was used to start Arak activated sludge WWTP up, which took in advantages of the other methods. Primarily just one of the basins was in the lane and wastewater entered the plant part by part. At first 1/30, second week 1/15, third week 1/6, and fourth week 1/3 of total inflow came to the plant. Observing little progress of biomass gain, some sludge from a similar treatment plant was added to the system, as seed. This procedure continued so the MLSS of the system, attained the 1/3 total design MLSS which was design MLSS of one basin. In the next two weeks, by using developed sludge of the self-system the second and third basins came in the lane and inflow increased to 2/3 and total flow, respectively. Finally after two months of beginning the start-up and one month after adding the seed total desired biomass was developed and the plant started to waste sludge. Because of cold weather start-up period took a longer time than expected. But even before developing biomass environment friendly results were achieved. After attaining design MLSS, BOD5 and COD removal from 40% and 60% increased to 90% and TSS removal from 70% reached to 96%. Less loading, less foam forming, no bacteriologic and chemical problems, better process control, using less seed, saving costs in sludge transport and avoiding relevant problems were the main advantages of this method.

Current Status of Sludge Collection, Transportation and Treatment in Ho Chi Minh City

In the process of construction and development, Ho Chi Minh City is discharging about six types of sludge: 1) sludge from urban wastewater drainage systems; 2) sludge from industrial wastewater drainage system; 3) sludge from the canal dredging activities periodically; 4) sludge from septic tanks; 5) sludge from the water treatment station/plant; 6) sludge from the construction sites. Sludge’s components are very different among types of sludge, sludge from the sewer network and canal dredging contain mainly sand and soil (70% - 90% dry weight), while the sludge from the wastewater/water treatment station/plant and from septic tanks contain mainly biodegradable organic substances (55% - 80% dry weight). The concentrations of all above-mentioned sludge (except sludge from the hazardous industrial wastewater treatment plant) are lower than toxic threshold. The volume of total sludge is about 3000 - 4000 m3/day (5000 - 6000 tons/day), excepting the amount of sludge generated from the water treatment plant (which is collected and treated separately). Sludge from wastewater treatment plants and septic tanks is collected, transported and recycled to become organic fertilizer. The other types of sludge are collected, transported, and disposed at the “unknown” locations, even though they have different values for use.

Geotextile dewatering of flocculated, fiber reinforced fly-ash slurry

Coal-based thermal power plants are a principal source of power generation in many industrialized countries. Consequently, fly ash and other coal combustion residuals are produced in significant quantities and must be appropriately managed, most commonly using wet-storage impoundments. Concurrent with diminishing impoundment capacity and increasing beneficial reuse of coal residuals worldwide, legislation is proposed in the US to close or liner retrofit all existing impoundments. Each of these progressions necessitates an increase in the dredging, dewatering, and transport of wet-disposal ash sludge. In recent years, geotextile tubes have increasingly been used to efficiently and economically dewater a number of low percent-solids sediments, by-products, and wastes. A laboratory investigation was conducted for studying the efficacy of geotextile tubes for dewatering hydraulically transported fly ash slurry. The dewatering behavior of unmodified fly ash was compared with that of specimens reinforced with randomly dispersed flexible PVA fibers and/or flocculated with optimized polyacrylamide. Results indicate that geotextile tubes can be effectively used for dewatering flocculated fly ash slurries and that the strength of retained fly ash can be significantly improved by adding reinforcement fibers at 1% of dry solids mass.

Dynamic behavior and concentration distribution of granular sludge in a super-high-rate spiral anaerobic bioreactor

Dynamic behavior and concentration distribution of granular sludge is highly dependent on the ecological environment of microbial communities and substrate degradation efficiency along bed height. Both were modeled and verified through experiments in a super-high-rate spiral anaerobic bioreactor (SSAB). The sludge transport efficiency of upmoving biogas (kt,n−1) displaying dynamic behavior of granular sludge in SSAB were predicted and found to be much lesser than of upflow anaerobic sludge blanket (UASB). The bed concentration distribution (Cm,n−1/Cm,n) which represented concentration distribution of granular sludge were also quantitatively predicted in two feeding strategies. Parametric sensitivity suggested that kt,n−1 was significantly influenced by spiral angle, outer radii of spiral rectangular channel, settling velocity of granular sludge and superficial liquid velocity (vl), while Cm,n−1/Cm,n was affected by vl and superficial biogas velocity. In addition, some measures were also suggested to optimize designs and operations of such bioreactors.

Quantification of greenhouse gas emissions from sludge treatment wetlands

Constructed wetlands are nowadays successfully employed as an alternative technology for wastewater and sewage sludge treatment. In these systems organic matter and nutrients are transformed and removed by a variety of microbial reaction and gaseous compounds such as methane (CH4) and nitrous oxide (N2O) may be released to the atmosphere. The aim of this work is to introduce a method to determine greenhouse gas emissions from sludge treatment wetlands (STW) and use the method in a full-scale system. Sampling and analysing techniques used to determine greenhouse gas emissions from croplands and natural wetlands were successfully adapted to the quantification of CH4 and N2O emissions from an STW. Gas emissions were measured using the static chamber technique in 9 points of the STW during 13 days. The spatial variation in the emission along the wetland did not follow some specific pattern found for the temporal variation in the fluxes. Emissions ranged from 10 to 5400 mgCH4/m2d and from 20 to 950 mgN2O/m2d, depending on the feeding events. The comparison between the CH4 and N2O emissions of different sludge management options shows that STW have the lowest atmospheric impact in terms of CO2 equivalent emissions (Global warming potential with time horizon of 100 years): 17kgCO2eq/PEy for STW, 36kgCO2eq/PEy for centrifuge and 162kgCO2eq/PEy for untreated sludge transport, PE means Population Equivalent.

Sludge quality aspects of full-scale reed bed drainage

Sludge-drying reed beds can be a cost-effective and sustainable solution to surplus activated sludge dewatering and mineralization, especially for small wastewater treatment plants. However, the simplicity as well as low energy and monitoring requirements of this technology are often counterbalanced by frequent operational problems consisting of slow and insufficient dewatering, poor vegetation growth, odor, and overall poor mineralization of the sludge residues. The main reason is that the general rules for facility design and operation are based on empirical experience rather than on the actual and current sludge parameters. In this study a new method for the assessment of activated sludge drainage properties has been applied to determine the reasons behind operational problems faced by the operators of reed bed facility accepting surplus activated sludge from two wastewater treatment plants in Esbjerg, Denmark. The importance of sludge quality monitoring as well as the damaging effect of shear forces, oxygen depletion, and long-distance sludge transportation were demonstrated. Finally, more general guidelines for reed bed facility design and operation are given, based on experimental data from seven full-scale plants.

Optimisation of sludge treatment and transport

In this paper we describe some work carried out in the UK into improving the effectiveness of a waste treatment and distribution network. Sludge is the name given to (treated) waste water and sewage. It is collected at small facilities and requires further treatment before it can be disposed of. We develop a linear programming model for the problem of effectively treating and distributing sludge. This model has been implemented in a large UK regional water company, Yorkshire Water.

A Study on the Characteristics of Zeolite-Enhanced Activated Sludge in the A/O Biological Nitrogen Removal Process

This paper mainly studies the use of the activated sludge process with zeolite to upgrade the traditional secondary water treatment plants. With the addition of an appropriate amount of zeolite, the living environment of several micro-organisms in the activated sludge can be improved, thus raising the activity and number of micro-organisms and increasing the level of nitrification. Simultaneously, it also can improve size distribution and structure of sludge particles, the settling property, thus reducing the specific resistance of sludge. However, excess doses of zeolite will increase the viscosity of the sludge, which will reduce the compression performance in sludge thickening. This is not favorable to the operation of the secondary sedimentation tank and the pipeline transport of sludge. Therefore, we suggest the further study of the lower doses of zeolite, to find the optimum effect and eliminate the negative ones.

Rheological study and valorization of waste sludge from wastewater treatment plants in the dredging operation of hydraulic dams

The wastewater resulting from various urban activities cannot be directly released back to natural environment because they contain various pollutants, including organics and minerals causing potential various types of diseases. Instead, wastewater must be purified prior to its release, which leads the production of waste sludge. A large quantity is produced from a wastewater in the purifications plants. An activated treatment of sewage wastewater also results in the generation of a considerable amount of excess sludge. This sludge must be disposed of safely. Commonly used disposal practices comprise of incineration, landfilling and application. The cost for sludge treatment is highly dependent on the volume and water content of the produced waste sludge. Treatment and disposal of an excess sludge in a biological wastewater treatment system requires a very high cost which accounts for approximately 35–60% of the whole operation cost of a wastewater treatment. In this study we propose a technique less expensive and more convenient. This technique is based on the use of sludge to reduce the loads losses during the dredging operation of hydraulic dams. The rheological study of mixtures of mud of dam and sludge from purifications plants showed a reduction of the yield stress of mud of dam up to 95%. Therefore the use of sludge from purifications plants during the dredging operation of dams facilitates the transport of sludge of dam.

Technical, economic and environmental assessment of sludge treatment wetlands

Sludge treatment wetlands (STW) emerge as a promising sustainable technology with low energy requirements and operational costs. In this study, technical, economic and environmental aspects of STW are investigated and compared with other alternatives for sludge management in small communities (<2000 population equivalent). The performance of full-scale STW was characterised during 2 years. Sludge dewatering increased total solids (TS) concentration by 25%, while sludge biodegradation lead to volatile solids around 45% TS and DRI24h between 1.1 and 1.4 gO2/kgTS h, suggesting a partial stabilisation of biosolids. In the economic and environmental assessment, four scenarios were considered for comparison: 1) STW with direct land application of biosolids, 2) STW with compost post-treatment, 3) centrifuge with compost post-treatment and 4) sludge transport to an intensive wastewater treatment plant. According to the results, STW with direct land application is the most cost-effective scenario, which is also characterised by the lowest environmental impact. The life cycle assessment highlights that global warming is a significant impact category in all scenarios, which is attributed to fossil fuel and electricity consumption; while greenhouse gas emissions from STW are insignificant. As a conclusion, STW are the most appropriate alternative for decentralised sludge management in small communities.

Efficiency assessment of a reed bed pilot plant ( Phragmites australis) for sludge stabilisation in Tuscany (Italy)

‘Abstract The aim of this study is to investigate the efficiency of a reed bed pilot system planted with macrophytes ( Phragmites australis ) in the stabilisation and dewatering of sludge. The water content of sludge was positively correlated with the biochemical activity (i.e. dehydrogenase activity (DH-ase) and respiration rate) under a wide range of redox conditions (aerobic–anaerobic). Mineralization processes seemed to be uninfluenced by seasonal changing. The metabolic index given by the ratio DH-ase/WSC increased with time from 0.007 to 0.02, implying that sludge organic matter mineralization was approaching maximum efficiency. Aerobic mineralization processes were quickly activated, as shown by the production of ammonia at 3 days and nitrate at 15 days. Nitrates conditioned the redox potential of sludge to relatively high values: from +50 to +150 mV in summer and +10 to +100 mV in winter. The positive redox potentials supported the organic carbon respiration because nitrates function as electron acceptors in the absence or scarcity of free atmospheric oxygen in the deeper layers. All these factors allow the system to (i) operate longer, with high loads applications of sludge and in any climate conditions, thereby making feasible onsite sludge stabilisation and thickening, and (ii) avoid frequent sludge transportation outside the wastewater treatment plant.

Making urban excreta and wastewater management contribute to cities' economic development: a paradigm shift

Cities, as engines of economic growth and social development, require large quantities of natural resources to meet their inhabitants' economic and social needs. Good infrastructure and reliable service provision are key to sustaining cities' development. In this regard, they enhance investment opportunities and service access to vulnerable populations. In response to the lack of sanitation infrastructure, many governments, development agencies and NGOs usually implement programmes to provide latrines to poor and vulnerable populations. These programmes often do not link infrastructure provision and its necessary management requirements. As a result, the majority of ‘latrine-based’ cities do not have a reliable solution for emptying latrines, and for the transportation and treatment of faecal sludge and wastewater. When these infrastructures are available, they are disconnected from business opportunities which use resources such as water, nutrients or biosolids for their productive activities. This lingering failure in sanitation is putting a huge financial burden on municipalities who have to rely on permanent subsidies to operate and maintain infrastructures. The recent WHO guidelines on safe use of wastewater, excreta and greywater opens doors for reuse opportunities other than agricultural irrigation. It is leading towards a new paradigm. This paper discusses research needs to link urban sanitation management to cities' economic development agenda.

Economic evaluation of combined treatment for sludge from drinking water and sewage treatment plants in Japan

Research Article| May 01 2009 Economic evaluation of combined treatment for sludge from drinking water and sewage treatment plants in Japan Tomoaki Miyanoshita; Tomoaki Miyanoshita 1Organo Corporation, Nishionuma 4-4-1, Sagamihara-shi, Kanagawa 229-0012, Japan E-mail: miyano-t@organo.co.jp Search for other works by this author on: This Site PubMed Google Scholar Naoki Oda; Naoki Oda 2Ishigaki Corporation, Nishihara 3-3-31, Yodogawa-ku, Osaka 532-0003, Japan Search for other works by this author on: This Site PubMed Google Scholar No Hayashi; No Hayashi 3Japan Water Research Center, Toranomon 2-8-1, Minato-ku, Tokyo 105-0001, Japan Search for other works by this author on: This Site PubMed Google Scholar Masahiro Fujiwara; Masahiro Fujiwara 3Japan Water Research Center, Toranomon 2-8-1, Minato-ku, Tokyo 105-0001, Japan Search for other works by this author on: This Site PubMed Google Scholar Hiroaki Furumai Hiroaki Furumai 4The University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-0033, Japan Search for other works by this author on: This Site PubMed Google Scholar Journal of Water Supply: Research and Technology-Aqua (2009) 58 (3): 221–227. https://doi.org/10.2166/aqua.2009.043 Article history Received: May 01 2008 Accepted: September 02 2008 Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Cite Icon Cite Permissions Search Site Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentAll JournalsThis Journal Search Advanced Search Citation Tomoaki Miyanoshita, Naoki Oda, No Hayashi, Masahiro Fujiwara, Hiroaki Furumai; Economic evaluation of combined treatment for sludge from drinking water and sewage treatment plants in Japan. Journal of Water Supply: Research and Technology-Aqua 1 May 2009; 58 (3): 221–227. doi: https://doi.org/10.2166/aqua.2009.043 Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex In Japan, water supply utilities need to renovate their sludge treatment facilities. This study therefore evaluated treatment of the sludge from drinking water treatment plants (DWTP) by two approaches: an individual system and a combined system. In the individual treatment scenario, the DWTP treats the sludge using its own facilities, whereas in the combined treatment scenario, DWTP sludge is transported to a sewerage system. The construction cost is much lower for combined treatment than individual treatment, while the operation cost is higher for combined treatment owing to the sewer charge. However, the additional sewer charge is less than the increase in cost for constructing an individual sludge treatment system. With the combined treatment system, sludge must be transported from the DWTP to a sewage sludge treatment plant (SSTP). A cost analysis reveals that sludge transportation by road is less beneficial than by pipeline in the sewerage system unless the plants are nearby. In economic terms, combined treatment and a sludge liquor pipeline is the most advantageous of all cases. The total cost depends on the given conditions and assumed unit costs. Sensitive parameters are the sewer charge and the distance between the DWTP and sewer pipeline. cost analysis, drinking water treatment, sewage works, sewer charge, sludge treatment, turbidity This content is only available as a PDF. © IWA Publishing 2009 You do not currently have access to this content.

Influence of thermally activated paper sludge on the behaviour of blended cements subjected to saline and non-saline environments

One of the problems to affect Portland cement matrices is low resistance to aggressive agents, due principally to the presence of a high content of portlandite in the hydrated cements. Pozzolanic materials have played an important role in the improving the durability of cement-based materials for decades. This work studies the behaviour of cement mortar matrices blended with 10% calcined paper sludge (source for metakaolinite) and exposed to different environmental conditions (saline and non-saline environments) after 6 and 12 months of exposure. Two cements were studied: an ordinary Portland cement (CEM 1, 42.5R), acting as reference cement, and a blended cement formulated by mixing 90% (by mass) of CEM 1, 42.5R with 10% (by mass) of paper sludge calcined at 700 degrees C for 2 h. The specimens were exposed 1 year to saline and non-saline environments. All the mineralogy samples were studied through X-ray diffraction and scanning electron microscopy (SEM) equipped with an energy dispersive X-ray analyser. The in-depth study on ionic mobility was performed on samples subjected to natural exposure (coast and tableland) for 6 and 12 months. Portland cement was composed of quartz, calcite, calcium hydroxide and tobermorite gels. The pozzolanic cement (10% calcined paper sludge) is of the same composition but a high calcite concentration and barium carbonate. SEM analysis from coastline show deposits of variable composition. The deposits are identified on the surface of different mineral components. The minerals from tableland are much fractured, i.e. calcite and feldspars. Inside the fractures, the deposits and the ions are located and trapped superficially. SEM analysis of control cement Portland and 10% calcined paper sludge shows deposits on quartz and calcite with a very high concentration of Pb, Zn, Cl and barium sulphate. A very porous aspect is due to the presence of the different aggregate types. This porous configuration permits retention of the ion environment. The pozzolanic cement in environments subject to the saline mist favours the retention and transport of ions observed. Something similar also happens with the increase in exposure to outdoor weather. Non-saline samples show temperature changes (ice or thaw cycles). Barium retention is kept on the surface in fracture lines by the gelification processes. In general, it may be inferred that an increase in exposure time increases the diffusion of ions towards test piece interiors. The chemical composition profiles show that the ions present different penetration speeds. The results indicate the better vulnerability of pozzolanic cements from calcined paper sludge in saline and non-saline environments. The cements with a 10% addition of calcined paper sludge favour retention and transport of ion has been observed. Today, projects are centred on a new recycling line for industrial waste of this kind, with special attention on its incorporation in cement manufacture as a pozzolanic material, setting the most appropriate activation conditions of the mineralogical compound in this waste (kaolinite and metakaolinite) and taking them as a starting point for this project. The use of pozzolanic cement with 10% addition of calcined paper sludge is a system which favours ionic retention.

Solids Loading Limitations of Rectangular Secondary Clarifiers

Basin configuration and equipment design govern whether rectangular secondary clarifiers will experience problems of inadequate sludge transport capacity. The operating factors to be considered, other than peak flows which may be severe, are the potential for sludge bulking and the higher mixed liquor suspended solids concentrations and solids retention times employed for biological nutrient removal processes. Rectangular clarifiers longer than 20 m and loaded at more than 3.5 kg∕ m2 day often have sludge transport/shortcircuiting problems. Shortcircuiting of mixed liquor into the return sludge is a common situation that can be avoided in new designs and easily corrected in existing facilities. A step-by-step design approach is presented as a series of process calculations with graphs. Results from the unmodified and the improved rectangular clarifiers at Phoenix 91st Avenue wastewater treatment plant, Ariz., are presented.

Co‐Conditioning of the Anaerobic Digested Sludge of a Municipal Wastewater Treatment Plant with Alum Sludge: Benefit of Phosphorus Reduction in Reject Water

In this study, alum sludge was introduced to co-conditioning and dewatering with an anaerobic digested sludge from a municipal wastewater treatment plant, to examine the role of the alum sludge in improving the dewaterbility of the mixed sludge and also in immobilizing phosphorus in the reject water. Experiments have demonstrated that the optimal mix ratio for the two sludges is 2:1 (anaerobic digested sludge:alum sludge: volume basis), and this can bring approximately 99% phosphorus reduction in the reject water through the adsorption of phosphorus by alum in the sludge. The phosphorus loading in wastewater treatment plants is itself derived from the recycling of reject water during the wastewater treatment process. Consequently, this co-conditioning and dewatering strategy can achieve a significant reduction in phosphorus loading in wastewater treatment plants. In addition, the use of the alum sludge has been shown to beneficially enhance the dewaterability of the resultant mixed sludge, by decreasing both the specific resistance to filtration and the capillary suction time. This is attributed to the alum sludge acting in charge neutralization and/or as adsorbent for phosphate in the aqueous phase of the sludge. Experiments have also demonstrated that the optimal polymer (Superfloc C2260, Cytec, Botlek, Netherlands) dose for the anaerobic digested sludge was 120 mg/L, while the optimal dose for the mixed sludge (mix ratio 2:1) was 15 mg/L, highlighting a huge savings in polymer addition. Therefore, from the technical perspective, the co-conditioning and dewatering strategy can be viewed as a "win-win" situation. However, for its full-scale application, integrated cost-effective analysis of process capabilities, sludge transport, increased cake disposal, additional administration, polymer saving, and so on, should be factored in.

CO-CONDITIONING OF DIGESTED EXCESS ACTIVATED SLUDGE WITH ALUM SLUDGE: BENEFIT OF PHOSPHORUS REDUCTION IN REJECT WATER

In this study, alum sludge was introduced into co-conditioning and dewatering with an anaerobic digested activated sludge to examine the role of the alum sludge in improving the dewaterbility of the mixed sludge and also in immobilizing phosphorus in the reject water. Experiments have demonstrated that the optimal mix ratio for the two sludges is 2:1 (anaerobic digested sludge:alum sludge; volume basis), and this can bring about 99% phosphorus reduction in the reject water through the adsorption of phosphorus by Al in the sludge. The phosphorus loading in wastewater treatment plants is itself derived from the recycling of reject water during the wastewater treatment process. Consequently, this co-conditioning and dewatering strategy can achieve a significant reduction in phosphorus loading in wastewater treatment plants. In addition, the use of the alum sludge can beneficially enhance the dewaterbility of the resultant mixed sludge by decreasing both the SRF and the CST, due to the alum sludge acting as a skeleton builder. Experiments have also demonstrated that the optimal polymer (Superfloc C2260) dose for the anaerobic digested sludge was 120 mg/l while the optimal dose for the mixed sludge (mix ratio 2:1) was 15 mg/l, highlighting a huge saving in polymer addition. Therefore, from the technical perspective, the co-conditioning and dewatering strategy can be viewed as a “win-win” situation. However, for its full-scale application, integrated cost-effective analysis of process capabilities, sludge transport, increased cake disposal, additional administration, polymer saving etc. should be factored in.

Evaluation of conditioning responses of thermophilic-mesophilic anaerobically and mesophilic aerobically digested biosolids using rheological properties

One of the most crucial processes in biosolids management is stabilisation, which is typically accomplished using either anaerobic or aerobic digestion processes. Although there are many advantages to both of these methods--such as reduction of volatile organic matter, pathogen content, and offensive odours--one common disadvantage is that digested biosolids exhibit poor dewaterability characteristics. The deterioration in dewaterability of digested biosolids leads to increases in polymer requirements, connoting higher conditioning costs. Many studies have examined this phenomenon based on conventional filterability tests such as capillary suction time and specific resistance to filtration. However, these test methods are limited in their ability to predict full-scale dewatering behaviour (particularly in centrifugation), and do not regard handling properties as being important for sludge transport. For this purpose, new rheometric methods may assist in predicting sludge behaviour, potentially allowing optimisation of stabilisation and conditioning processes relative to the desired sludge properties. This paper investigates the possible utility of these methods. Classical methods for characterising biosolids, such as filtration tests, are compared with yield stress values and other rheological properties as determined using the steady-shear rate sweep test. The rheological behaviours are compared for different sludge types, including raw and polymer conditioned thermophilic anaerobically, mesophilic anaerobically, and mesophilic aerobically digested biosolids. The paper demonstrates the determination of specific energy values associated with breakdown of the flocculated matrix. Robust modelling approaches are employed to optimise the conditioning of the digested samples, and to shed light on commonly used rheological models such as Bingham, Herschel-Bulkley, and Ostwald equations.

Piston diaphragm pumps for handling sludge and sediment

The transportation of sludge and sediment cannot always be easily moved from remote locations, and pump systems are often seen as the best solution. Dipl.-Ing. Friedrich Wiechmann (graduated engineer), head of development and construction, ABEL GmbH & Co. KG, Büchen explains why piston diaphragm pumps are suitable for high pressure sludge transportation.