Sludge disposal – less is more

Clear solutions for sludge treatment

Alfa Laval has the focus, the technologies and theknow-how to deliver the best, most cost-effectivesolution for modern sludge treatment.

Meeting legislative requirements for efficient, environmentally friendly sludge disposal demandsnew approaches – and Alfa Laval delivers.

2 Clear solutions for sludge treatment

Experience countsAlfa Laval has over forty years of practicalexperience with sludge treatment.Today, Alfa Laval is involved in the processing of municipal sludge from atleast 200 million people. Our solutionsare used in more than 1,000 industrialapplications, and our systems help produce 1.5 million cubic metres ofpotable water every day.

We deal with all kinds of sludges,whether they come from simple naturalsedimentation, secondary biologicaltreatment or advanced tertiary chemicaltreatment.

A challenge to deal withOne characteristic common to all sludges – both from industrial sources and fromthe public sector – is that they are normally of little or no commercial value.They therefore represent a challengingdisposal problem that is often costly todeal with. Alfa Laval solutions aredesigned to reduce these disposalcosts significantly.

Experience adds up to savingsAlfa Laval G2 decanter centrifuges, spiral heat exchangers and drum thickeners save on more than just thedirect costs of sludge disposal.

Alfa Laval’s expert analyses make sure we provide the most cost-effectivesolution to specific customer requirements. Process expertise fromhundreds of projects all over the world makes a crucial difference inimplementing any complex solution thatinvolves the treatment of sludge.

We speak sludge disposalVirtually all kinds of industrial activity and urban development result in sludge that needs to be disposed of.The question is how well it can be done, and at what cost.

Digester heatingThe Amsterdam WWTP has a capacity of 1.1 millionP.E. Alfa Laval supplied six 730-kW ALSHE spiral heatexchangers for the digester heating and four decantercentrifuges for dewatering the digested sludge.

The ALSHE copes with high sludge concentrationsof up to 6%. The design means only occasionalcleaning is required, and the hinged cover makes iteasy. All six units are located in the basement, andthe compact design means they take up little space.

These units were selected for their reliability. “We arehappy with the installation as it is. Reliability is veryimportant and we trust the Alfa Laval spirals.”

Mr. R. Ramkisoen, plant manager, the AmsterdamWWTP, the Netherlands

For the operatorAlfa Laval sludge treatment equipmentand solutions add up to:• lower polymer consumption, higher

cake dryness, clearer effluent and greater capacity

• lower operating costs due to greater efficiency

• fully integrated solutions from one single source, guaranteed to work together

• expert on-the-spot local service, backed by comprehensive maintenance and spare parts services

For contractorsAlfa Laval makes it possible to:• reduce the technical uncertainties

involved in any tender• minimize engineering costs and

overall purchasing costs• reduce installation and start-up costs • boost and strengthen the overall bid

due to Alfa Laval’s technical capacity

The ideal partnerThis makes Alfa Laval the ideal partnerin any sludge treatment project thatfocuses on:• cost efficiency, both short-term and

long-term• full compliance with environmental

legislation• innovative processes that meet and

exceed all requirements

Treatment of potable water“As part of our dedication to environmental protection, we are very happy with the two Alfa Laval ALDEC 506 decanters for dewatering the sludge. They were chosen mainly because of their automatic control system, which ensures easy, error-free operation. The machinery requires little space compared with belt filter presses, which has made installation a lot easier and given us substantial savings.”

Wang Wei, Director, Minhang Water Treatment Plant, China

Minimizing the volume of industrial wasteSpanish Recasa, a company specializing incollecting, treating and disposing waste fromindustrial companies, has installed an AlfaLaval ALDEC G2 decanter to be used in the dewatering process. The decanter produces asludge cake with a dryness of 35 per cent,and the water is clean enough to pipe to theindustrial estate's regular wastewater plant."Look at the water coming out. It's almostclean enough to drink."

Mariano Miguel Arias, General Manager andfounder, Recasa, Spain

6 Clear solutions for sludge treatment

The pressure is onAlfa Laval technology eliminates process bottlenecks

Influent

Screen/Grit removal

Scum dewatering

Return sludge

Primaryclarification

Thickening

Aeration

Dewatering

Preheating

Thickening

Thickening

Effluent cooling

Digester heating/Pasteurization

Heat recovery

Sludgedigester

Preheating

Process optimization

Process enhancement

P

Alfa Laval G2 decanter centrifuges,drum thickeners and spiral heatexchangers are the equipment ofchoice for use in:

ThickeningThe Alfa Laval thickening systemreduces sludge volume by up to 90%.This means significant savings whentransporting the sludge elsewhere forfurther treatment. The digestion processis also optimized due to the longer residence time, which results in bettergas yield, improved stabilization andlower heating costs. Use of thickeningbefore dewatering also improves theoverall operating economics of thedewatering plant.

DewateringDecanter centrifuges work by multiplyingthe effects of gravity several thousandtimes, with centrifugal force separatingout the solids in a fraction of the time itwould otherwise take.

Dewatering is essential to reduce thevolume of the sludge as well as toensure a dry sludge cake. Dewateringreduces transportation and disposal or drying costs, while at the same time limiting any adverse effects on the environment.

Clear solutions for sludge treatment 7

Sludge preheatingPreheating the sludge to 60°C or higherbefore dewatering alters the sludgecharacteristics and makes it easier todewater. Using Alfa Laval spiral heatexchangers means that cake drynesscan be increased by up to 6% by preheating. In cases where dryness isalready sufficient, preheating can saveup to 40% on polymer consumption.

Sludge pasteurizationEnvironmental legislation all over theworld sets limits on the quantities ofpathogens and microbes that are permitted to be present in the sludgebefore disposal. These limits can beadhered to effectively by pasteurization,which involves heating the sludge to70°C for thirty minutes. Using AlfaLaval spiral heat exchangers to do thismakes it possible to exceed even themost stringent standards for the elimination of pathogens, at the sametime as saving energy by recoveringheat between two sludge flows.

Total solutionNovozymes, the world´s largest producerof industrial enzymes, is extending thenumber of ALDEC decanters installed inits treatment plant to dewater the bio-mass by-product.

“Alfa Laval delivers a complete system,with guaranteed compatibility betweensludge unloading systems, lime silos,

polymer equipment, controls, pumps,valves and decanters. Alfa Laval is very familiar with our needs and our productionprocesses, and knows that our ability tohandle the specific quantities of liquidwaste on time depends on everythingbeing fully optimized at all times.”

Niels-Viktor Nielsen, Process Manager,Novozymes, Denmark

Secondaryclarification

Dewatering

Dewatering

Directdewatering

Preheating

Preheating

Final effluent

Digestion heatingBecause digesters operate most effi-ciently above ambient temperature,heating is required. Alfa Laval spiralheat exchangers are the most efficientway to do this, heating the sludge in asmooth, well-controlled way in a recir-culation loop.

This improves the digestion process,and gas production increases when thedigesters are maintained at a stabletemperature.

Effluent coolingIn some industrial waste treatmentprocesses, it can be necessary toreduce the temperature of certain wastestreams, as high temperatures canimpair the efficiency of the subsequenttreatment stages. Alfa Laval spiral heatexchangers provide a reliable, efficientway of doing this.

Good results – the sum of many partsAlfa Laval – providing technologies developed specifically for sludge treatment

Alfa Laval high-performance solutionsare built around quality products:

• ALDEC G2 decanter centrifuges• ALDRUM drum thickener systems• ALSHE spiral heat exchangers

All products are available in a widerange of different versions designed tomeet individual customer requirements.These cover the entire spectrum, fromstraightforward configurations withprime focus on the initial purchaseprice, to state-of-the-art installationswith unbeatable life-cycle costs.

Value for moneyAlfa Laval sludge treatment equipmentprovides every customer with value formoney, because it is all designed and

built using a flexible, modular approachthat can meet even the toughest challenges.

This means that each and every component and assembly can be configured to meet individual needs,from the basic high-performance unitsupwards.

With Alfa Laval equipment, you only payfor what you really need – nothing more.

8 Clear solutions for sludge treatment

Thickening for improved dewateringThe CCM Brewery Group in Mexicoproduces many well-known beers,including SOL. The Group successfullytested the ALDRUM drum thickenerand subsequently purchased the module for their factory in Guadelajara.“We were impressed with the simplicityand the efficiency of the ALDRUM. Thethickening process is ideal both forimproving the effectiveness of thedigester, and in preparing for dewateringwith our ALDEC decanter.”

Alfonso J. Cantu Q., EnvironmentManager, CCM Group, Mexico

Advantages in commonAll the equipment supplied by Alfa Laval – be it a decanter centrifuge, a drumthickener or a spiral heat exchanger –has important characteristics in common.

• The processing sections are fully enclosed. This ensures maximum protection of staff from risks associatedwith exposure to chemical and biological aerosols.

• The equipment takes up only a fraction of the floor space needed foralternative technologies. An Alfa Lavalsolution thus boosts plant capacity without additional construction costs.

• They are easy to operate, supervise and service, thereby reducing costs still further.

• Sludge in any form is abrasive. In Alfa Laval equipment, the critical parts are therefore made of wear- resistant material.

• Alfa Laval has developed unique feed zones that ensure superior per-formance in centrifuging, filtering andheating processes.

These advantages are available in theform of separate units, packages ofcomponents, pre-engineered modulesor turnkey plants.

For us at Alfa Laval, our obligation toyou as a customer does not stop short at delivery. Our Parts & Serviceorganization is there to ensure that your process always runs at peak performance. This is a commitment that extends throughout the lifetime of the system. We call it NonstopPerformance.

Nonstop Performance is based on ourglobal network of experts, who arealways on standby to provide you withgenuine spare parts on site, in morethan 50 countries, 365 days a year,right around the clock.

In terms of service, we speak your language. Alfa Laval service is based on a profound insight into the needs ofthe sludge treatment industry. We seeevery product as part of a process andunderstand the role it plays within thatprocess. We can therefore work inclose collaboration with you to tailor anindividual service package that matchesyour requirements perfectly.

Service must result in bottom-line benefits. We therefore help you to calculate the savings that will resultfrom any proposed service package,and the real-term benefits it will provide.

Challenge us to show you!

Nonstop PerformanceA lifetime commitment

10 Clear solutions for sludge treatment

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Alfa Laval in briefAlfa Laval is a leading global provider ofspecialized products and engineeredsolutions. Our equipment, systems andservices are dedicated to helpingcustomers to optimize the performanceof their processes. Time andtime again.

We help our customers to heat,cool, separate and transport productssuch as oil, water, chemicals,beverages, foodstuffs, starch andpharmaceuticals.

Our worldwide organization worksclosely with customers in almost 100countries to help them stay ahead.

How to contact Alfa LavalUp-to-date Alfa Laval contact details forall countries are always available on ourwebsite at www.alfalaval.com