NEWS
EDITION 10 | SEPTEMBER 2016
NIJHUIS NEWS MAGAZINE CONTENT: RESOURCE RECOVERY as a new business model Real-time pollution control to REDUCE CHEMICAL COSTS Nijhuis around the world: - Retrofit of a WWTP with i-DOSE - 20,000 m3 WASTEWATER is treated every day Turn your WASTEWATER INTO BIOGAS in one process Changing the mindset: Turn flotation fat into BIOFUEL
RESOURCE RECOVERY
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AS A NEW BUSINESS MODEL
Read the complete interview from Water Forum Magazine with Menno M. Holterman on our Nijhuis Industries website.
Click Here >>
Nijhuis Industries NEWS I www.nijhuisindustries.com
Putting water on the map is a global objective. Not only in places that face water scarcity but also in the ‘land of plenty’, the Netherlands, albeit for different reasons. Here, water inspires yet another interesting chapter in the continuing story of what could well be termed, a complicated relationship. The aim of sustainable reuse of wastewater has produced a considerable wastewater technology sector in the Netherlands. Menno M. Holterman has been one of the ‘game changers’ in this sector at Nijhuis Industries. Holterman spots a trend with his worldwide clientele to no longer consider reuse of wastewater a stand-alone option, but to integrate it in their sustainability management. He is a firm believer in decentralized solutions: keeping wastewater ‘concentrated and close’ as opposed to ‘diverted and diluted.’ Two important stages in the industrial process "The relatively new focus on resource recovery from waste and wastewater, builds on two important stages in the industrial process. Firstly, the notion that certain combined existing processes induce the recovery of valuable resources from waste and wastewater; and secondly, the developing of new processes to recover in a cost efficient way, those resources that hold a great value for our customers.
Help and support local companies to create the necessary sustainable infrastructure "Robust solutions are key in certain parts of the world, where people are not only in the process of acquiring knowledge and experience, but also have different approaches to water than we do. Offering expensive, sensitive and circular biological processes to customers who are not yet able to handle such innovative solutions, is like carrying coals to Newcastle. We prefer to customize our products to the needs of our clients and to local infrastructure, amenities and culture. That is why we not only sell our solutions to customers, but also hire them out as part of our own sustainability and cradle-to-cradle philosophy. That way we help and support local companies to create the necessary sustainable infrastructure until they are able to take over themselves. We create local consortiums of companies, ngo’s and other parties that function under our patronage."
Nijhuis Connect enables us to ‘stick to the customer’ as long as necessary and preferably 'for life' to guide them successfully through the process of transition to sustainability. We see it through together, so to speak, recognizing in the process that we owe our very existence as Nijhuis Industries to these customers." Turning (waste)water into profit "Wastewater often holds many valuable products. Take for instance, paper fibres. Abundant in our sewers, not easily degradable, and valuable to the paper and cardboard industry. The Dutch Water Boards are currently looking for ways to recover the fibres from the water with the aim of reusing them." It's just one of many examples of resource recovery from wastewater Menno M. Holterman mentions. “In England, we have been working with a slaughterhouse that produces ammonium sulphate out of their digestate. They paid £30 per ton to dispose of this waste product until we discovered that if we recover and purify it, the company could earn £130 selling it.” Nijhuis Industries also succeeds in making a PROFIT out of waste and wastewater by transforming it into energy. “In the meat-processing industry, vast amounts of fat are released that end up in their wastewater. Together with a client, we developed a solid and costeffective method to recover the fat and convert it into biodiesel, which was subsequently used as biofuel for the plant's boiler." Customers that became completely self-sufficient "Instead of buying a tank of heavy fuel oil once a week, the company could self-supply the plant with its own waste.” Menno M. Holterman stresses the endless possibilities in this area. “In the past few years we have been working on projects involving simultaneous processing of waste and waste water. Often so much energy was released during this process that electricity could be generated. We even have customers that became completely selfsufficient this way, as to their electricity supply. From waste and wastewater, a maximum amount of biogas was produced to run the plant. Needless to explain the benefits are twofold in view of corporate sustainability and improving their environmental footprint.” Interview Water Forum Magazine with Menno M. Holterman, CEO Nijhuis Industries
Nijhuis Industries NEWS I www.nijhuisindustries.com
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These are important developments that lead to new insights and commercial opportunities. All due to innovative and new treatment and recovery technologies, often combined with other technology fields. The market for resources thus generates an incentive to make choices in processes."
Nijhuis Industries Connect "Helpful in this process are the developments in the field of sensor technology and real-time data that enable us to monitor the performance of these projects from a distance. That way we do not have to be physically present all the time in Africa or Asia. One of our after-sales services, Nijhuis Industries Connect, offers customers service concepts that supply them with all the necessary information to optimize their performance under different circumstances.
Applying real-time pollution control to reduce chemical costs for DAF Dissolved Air Flotation (DAF) has been successfully applied as wastewater pre-treatment for many years. To guarantee the effluent quality; chemical dosing and aeration are set to deal with the peak loads of TSS and COD. Nijhuis i-DOSE, a tailor-made and smart dosing system, based on a total organic carbon (TOC) measurement for heavy polluted wastewater, in combination with real time feed forward control showed that chemical dose for coagulation and flocculation can be reduced and optimized. The i-DOSE system has been tested and incorporated in the new ‘Intelligent DAF’ which reduces the chemical consumption (approximately 25%) and lowers the energy requirement, by adjusting the aeration pressure according to the amount of solids in the incoming wastewater. The implementation of the ‘i-DOSE’ system generally results in a return on investment (ROI) of 1-2 years, depending on the amount of treated wastewater. The results show that i-DOSE can reduce yearly chemical costs up to 25% and in combination with the state-of-the-art i-DAF achieve high removal efficiencies for pre-treatment of industrial wastewaters.
HOW DOES IT WORK?
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By determining the real-time COD load of the influent, the chemical dosing can be optimized during the start-up of production (increasing COD load over time) and during cleaning (decreasing COD load over time). Additionally, the air to solids (A/S) ratio can be calculated based on the COD load in order to determine the required aeration flow or pressure in the recirculation system of the DAF system. To determine the real-time COD load, a specially developed TOC analyzer has been used to measure the influent pollution load. From lab analysis the TOC/COD ratio is determined, which enables our experts to derive the COD concentration from the TOC measurement. By using real-time feedforward dosing control, the consumption for coagulant (FeCL3), neutralizer (NaOH) and polymer are optimized, based on the COD load. An approximation of the amount of solids can be derived from the removed COD load. Reduction of the polymer consumption has not been included in this research due to the low yearly costs at this particular installation. Polymer consumption can, however, be easily reduced based on measuring the calculated sludge load.
Implementation of the i-DOSE system
The i-DOSE system has been developed at a red meat processing plant. During the first period the TOC analyzer was thoroughly tested for process stability and was calibrated for COD measurement. The results for calibration are shown in figure 1. Based on multiple grab samples, the COD concentrations have been determined at a laboratory. The results show that this type of red meat wastewater has a COD:TOC ratio of 4.1. This ratio has been confirmed by performing the same calibration on different days. After proving that the TOC analyzer achieves a stable performance and produces reliable TOC/COD measurements, several dosing algorithms were developed in order to optimize the chemical dosing for FeCL3 and NaOH. Figure 1 shows the results obtained from real-time COD control on wastewater of a red meat slaughterhouse. By optimizing the chemical dosing of FeCL3 and NaOH the controlled dosing is lower during start-up of production and during cleaning at the end of the production day, compared to the original fixed dosing of FeCL3 (yellow line) and NaOH (purple line). Furthermore, over dosing of ferric (or aluminum) will result in sludge with an increased inorganic content and increased sludge volume due to the precipitation of ferric hydroxides, which will increase the operational costs unnecessarily.
Nijhuis Industries NEWS I www.nijhuisindustries.com
24.000 20.000 16.000 12.000 8.000
Flow Coagulant [L/h] Flow Neutralizer [L/h]
COD [mg/L]
28.000
40
30
20
10
4.000 0 8 Jun 00.00
9 Jun 00.00
10 Jun 00.00
11 Jun 00.00
Set point FeCl3 without i-DOSE [L/h]
Dosing FeCl3 with i-DOSE [L/h]
Set point NaOH without i-DOSE [L/h]
Dosing NaOH with i-DOSE [L/h]
12 Jun 00.00
Overdosing FeCl3 Overdosing NaOH
COD concentration [mg/L]
Figure 1. COD concentration, coagulant (FeCL3) dosing and neutralizer (NaOH) dosing with i-DOSE compared to the previous fixed FeCL3 and NaOH dosing. Table 1 shows the operational cost savings for chemical consumption, sludge disposal and operator costs for a 50 m3/hr wastewater treatment system. The comparison of chemical consumption results in a reduction of 20% for FeCL3 and 41% for NaOH. Furthermore, 50% less operator time is required for daily inspections and a reduced chemical dosing results in a reduced sludge production of 3%. Combined, this results in a reduction of 25% of the total chemical dosing. The total yearly savings for implementing the i-DOSE system are, for this specific case, EUR 30,300,- per year, resulting in a ROI of less than 2 years. When the processed wastewater volume increases, at an equal concentration of COD, the ROI will decrease almost linearly, since the chemical dosing and sludge production will increase linearly with the wastewater flow. For a 100 m3/h installation the ROI will be less than a year. Unit
Costs EUR per unit
Chemical comsumption Without i-DOSE
With i-DOSE
Savings %
Yearly operational saving EUR/year
FeCL3
kg/d
0.19
728
582
20%
7,200
NaOH
kg/d
0.24
237
140
41%
6,100
Sludge
m3/d
15.00
50.1
48.4
3,4%
6,600
Operator
h/d
40.00
2
1
50%
10,400
Total yearly savings
30,300
ROI i-DOSE
< 2 Years
Table 1. Cost saving and ROI of the i-DOSE system.
WHY NIJHUIS I-DOSE?
The operational costs of wastewater treatment by DAF systems can be substantially reduced by using i-DOSE. The following operational savings were registered during a full-scale test at a red meat processing plant: • • • • •
The chemical dosing in a red meat processing plant can be reduced by approximately 25% (FeCL3 and NaOH reduction), depending on the COD fluctuations of the influent. Overdosing of metal salts will result in an increased inorganic content and volume of the produced sludge, 3% in this specific case. 50% reduction in operator attendance (in daily operational inspections, adjustments) Another advantage for real-time chemical dosing is that the volume of balance tanks can be reduced, since the system can deal efficiently with fluctuations in pollution load. This will only be applied at greenfield installations. In this case a balance tank was already present. ROI of 1 – 2 years, depending on the total wastewater volume treated.
Read more about i-DOSE and the i-DOSE paper on our Nijhuis Industries website. Click Here >>
Nijhuis Industries NEWS I www.nijhuisindustries.com
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Item
Read more about i-DAF and the i-DAF paper on our Nijhuis Industries website. Click Here >>
Intelligent Dissolved Air Flotation
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Superior municipal pre-treatment performance, compared to pre-sedimentation tanks.
Nijhuis Industries NEWS I www.nijhuisindustries.com
The i-DAF system has been succesfully proven as alternative for conventional pre-sedimentation tanks (PST). A single i-DAF system gives an improvement in removal efficiencies compared to traditional pre-sedimentation tanks. TSS removal increases from 25-40% in a traditional PST, to 70-80% for a DAF system with polymer dosing and >90% for a DAF system combined with polymer and coagulant dosing. The COD removal increases from 20-25% in a traditional PST, to 50-60% for a DAF system with polymer dosing and 60-70% for a DAF system combined with polymer and coagulant dosing. The aim of this study was to investigate the application of i-DAF as an alternative solution for pretreatment of municipal wastewater. The removal efficiency of total suspended solids (TSS), chemical oxygen demand (COD) and total phosphorus (TP) were investigated. In addition, a calculation was performed for the investment and operational costs of an i-DAF system in comparison to a conventional primary treatment system. Finally, the two systems were compared quantitatively.
i-DAF IN PRACTICE
A DAF installation was built inside a 40’ container and tested at the municipal WWTP of Rijn and IJssel at Olburgen, the Netherlands (Figure 1) from January until March 2012. This system consisted of a pipe flocculator, chemical dosing pumps – for dosing of neutralizing chemicals, coagulant and polymer – and a dissolved air flotation unit. The influent wastewater was pumped to the flocculator, where the chemicals were dosed to the water flow. Depending on the pH value an acidic or a caustic agent was dosed, followed by a coagulant (FeCl3; 33% diluted to 5%) and at the end of the flocculator a polymer (C494; 0.05%) was dosed. From the flocculator the chemically pre-treated water entered the flotation unit.
Parameter
Unit
i-DAF without chemical dosing
PST without chemical dosing
Design parameters Surface load
m/hr
25
1,5
DM primary sludge
%dm
6
2
Operational parameters COD & TSS removal efficiencies
+
0
Robustness
+
+
Footprint
+
0
Effect of hydraulic variations on effluent quality
0
0
Effect of variations in TSS loads on effluent quality
+
0
Possibility for higher removal efficiencies with additional chemical dosing
+
+
Energy consumption
0
+
Table 1. Quantitative comparison between DAF and pre-sedimentation tank
WHY NIJHUIS i-DAF?
This full-scale plant has proven that at a greenfield situation, i-DAF is performing better compared to PST. Moreover, DAF systems can be used as a (temporary) solution in, for example, WWTP renovation projects. A single i-DAF system gives an improvement in removal efficiencies compared to a traditional PST. TSS removal increases from 25-40% in a traditional PST, to 70-80% for a DAF system with polymer dosing and >90% for a DAF system combined with polymer and coagulant dosing. The COD removal increases from 20-25% in a traditional PST, to 50-60% for a DAF system with polymer dosing and 60-70% for a DAF system combined with polymer and coagulant dosing.
The investment and total yearly costs are lower for i-DAF without chemicals, compared to traditional PST. i-DAF shows higher removal efficiency of TSS and COD and maximizes carbon harvesting for anaerobic sludge digestion. Compared to PST, i-DAF has a lower footprint and can deal with variations in TSS load whilst maintaining good effluent quality. Moreover, i-DAF can be better adjusted compared to PST by adding chemical dosing to reach a high removal efficiency, in order to meet future restrictions on effluent discharge demands.
Nijhuis Industries NEWS I www.nijhuisindustries.com
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Figure 1. The DAF set-up inside the 40’ at Olburgen WWTP
The flocks float to the surface of the unit; this floating sludge layer was continuously scraped off and pumped to a sludge discharge. Part of the treated water was recirculated and aerated to add buoyancy to the flocks, enhancing their floating characteristics. The treated water leaves the flotation unit via an overflow weir. During this pilot test the influence of varying FeCl3 (0-100 mg/L) and polymer (0-4 mg/L) dosing rates were tested. Samples were taken from the influent and effluent and were analyzed on TSS, COD and TP concentration.
NIJHUIS AROUND THE WORLD
Middle East
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20,000 m3 wastewater is treated every day due to a Nijhuis rental system
A leading utility company in Saudi Arabia collects wastewater from several companies and petro-chemical industries. The wastewater is collected in aerated lagoons and then treated. In 2015, the customer needed a fast-track solution to treat an additional volume of wastewater which they succesfully contracted for early 2016. To meet the deadline and to run the plant beginning in January 2016, the customer approached Nijhuis signing the contract in July 2015. The customer chose Nijhuis particularly for the flexibility of our company, including the capability to manufacture all equipment ourselves. The installation will be rented for three years and consists of 9 Flotation Units (IPF 135E), 2 containerized dosing and power distribution systems and 3 decanters. Thanks to the standardization and prefabrication of IPF units at the Nijhuis Headquarters in Doetinchem, within 6 months Nijhuis completed the engineering, procurement, production, transport, customs, site work, installation and the startup. By January 2016 the plant was up and running, thanks to the efforts of the Nijhuis team during the Christmas Holidays. North-America
Retrofit of a WWTP with i-DOSE for treating pork wastewater A new pork processing company acquired the assets of a former beef plant in Minnesota and are upgrading and expanding the processing plant to slaughter 6500 head/d. The former beef plant had an existing wastewater treatment system, consisting of primary treatment followed by anaerobic and aerobic lagoons. The existing wastewater treatment plant is very old and required new equipment to treat the expected pollution load from the new pork processing plant. Nijhuis will supply new rotary drum screens, upgrade of the existing flotation unit (more than 20 years old) with a Nijhuis aeration system, a new equalization tank, flocculation and flotation system, including an i-DOSE system. The Nijhuis pretreated effluent will be polished via the existing anaerobic and aerated lagoons, before discharge to the city sewer. Nijhuis were chosen because of their vast meat (pork) processing experience and innovative technical approach. This considered utilizing existing equipment for fat flotation (without chemicals) to generate thickened sludge/oils & grease that would go to rendering as a revenue stream, followed by a flocculation-floatation system with automatic chemical dosing and control (i-DOSE), which offered the best effluent quality from a pretreatment system. Also, the ability to include i-DOSE reduced the volume of the required EQ tank, which was also important due to site space constraints. The system is expected to be operational in October 2016. Nijhuis Industries NEWS I www.nijhuisindustries.com
NIJHUIS AROUND THE WORLD
North-America
Turnkey contract for a bacon processing plant Nijhuis received a turnkey contract from a bacon processing plant in Kansas to design, engineer, build and commission a WWTP solution. The solution involves upgrading the existing wastewater treatment system to produce 450 m3/d of compliant effluent, suitable for discharge to the local municipal treatment plant. Nijhuisâ&#x20AC;&#x2122; experience, technical know-how and relationship from a previous successful project, was key to building confidence in the Nijhuis technical solution, that involves utilizing existing wastewater treatment infrastructure and reconfiguring the process to be more stable and robust. The Nijhuis technical expertise and project management were crucial in ensuring to offer the best technical solution for the short term. The system is also designed to test treatment capabilities and removal efficiency for future TP and TDS compliance limits. The project involves rental of a Nijhuis NPF 110 system for primary treatment (FOG and TSS removal ahead of existing biological treatment), retrofit of existing MBBR system, new piping and pumping systems and upgraded control systems. The project is underway and the system is expected to be producing compliant effluent by January 2017.
Asia Pacific
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Upgrade of a dairy plant in the Philippines In March of this year Nijhuis successfully secured a large project for the upgrade of a dairy plant in the Philippines. At that time, Nijhuis was also successful in supplying a rental unit consisting of a containerized flocculation system and an IPF90 flotation unit as a solution to solve the customers interim waste disposal issues. Nijhuis were fast to respond with an airlifted rental, allowing the equipment installation to begin in early May of this year Currently, the rental system is operational allowing the customer significant monthly savings on waste disposal. The government had recently tightened its environmental standards and the rental system helped the customer to achieve these requirements on an interim basis, until Nijhuis is able to ship and install the main system later this year.
One of the largest hatchery plants in Russia, which is producing 2.6 million eggs every day, also has its own slaughter line. There has been a Nijhuis primary treatment plant running for a number of years. The expansion of the production, increasing capacity and stricter effluent quality requirements, demands upgrade of the current WWTP installation with biological and polishing treatment.
Russia & CIS
Hatchery plant upgrades their WWTP and optimize chemical dosing with Nijhuis i-DOSE system
Due to increasing attention from the local authorities, they are forced to build an extension to reach a COD which is lower than 30mg/L. For that reason, Nijhuis will supply a biological system, sand filter (CSF) and a carbopure (CP40) system. In order to reduce the operational costs, the client has decided to install an i-DOSE system which takes an important role in optimal chemical dosing. The i-DOSE system will ensure less requirement of human intervention, which is highly desirable for the customer considering there is a large distance between the production plant and WWTP. Thanks to the i-DOSE system they will not have to frequently visit the WWTP anymore to adjust the chemical dosing. Nijhuis Industries NEWS I www.nijhuisindustries.com
NIJHUIS AROUND THE WORLD In March this year, a dairy factory in the Netherlands needed a rapid solution for their disinfection of the cooling water within two new build cooling towers. They started to firstly take one cooling tower in operation. A modular 10ft containerized ozone unit was directly available for rent for a period of 9 months. The unit had the advantage of being placed near the cooling towers because of the modular set-up and â&#x20AC;&#x2DC;plug and playâ&#x20AC;&#x2122; connection. Due to limited space and no traditional routes available to position the container, a crane hoisted the unit over the complex and positioned it between the cooling towers. With other disinfection methods proving unsuccessful, Nijhuis were able to offer a rapid and technically proficient disinfectant solution via ozone technology. Leaving no chemical residues and guaranteeing food safety, ozone disinfection continues to meet the requirements whilst safeguarding a corrosion-free environment, after the disinfection process.
The Netherlands
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Successful rental period for the disinfection of cooling water with ozone
The Netherlands
Nijhuis GENIAAL nominated for the Dutch Jan Terlouw Innovatieprijs 2016 Nijhuis is, with its unique manure treatment concept GENIAAL, nominated for the Dutch Jan Terlouw innovation prize. The prize was established in 2011 to boost (sustainable) innovations and technologies in eastern Netherlands. GENIAAL is a total solution for the processing of manure and converts raw manure or digestate from anaerobic digestion to clean water and bio-based phosphate, nitrogen and potassium fertilizer. GENIAAL is a cost effective, innovative and, above all, sustainable solution to the manure and phosphate surplus in the Netherlands. In consultation with Groot Zevert Vergisting, a large manure treatment company in Beltrum, the Netherlands, this unique solution is developed and tested.
Nijhuis expects that GENIAAL will not only make a significant contribution to solving the manure and phosphate problem in the Netherlands, but has also begun using its global sales and service centers to market GENIAAL. It is expected that this refining technology will play a key role to help farmers worldwide to treat manure in a sustainable way against the lowest possible cost and reduce their dependence on fertilizer. Besides the leading position Nijhuis has in the field of sustainable water use, GENIAAL will also help Nijhuis to gain a prominent position in the field of resource recovery in the coming years. Another great example of Nijhuis, solid solutions in a fluid world.
Africa
Potato processing plant will have a new pre-treatment system Nijhuis recently sold a pretreatment system to a potato processing plant in South Africa. The scope of supply includes a flocculation-flotation system with E-panel and associated equipment, which will pretreat potato processing wastewater for TSS and O&G removal. The Nijhuis flocculation and flotation system will be installed under a sun/rain shelter and located outside. The entire system is rated for IP65 conditions, dust and water free. The system is expected to be operational in fall 2016.
Nijhuis Industries NEWS I www.nijhuisindustries.com
NIJHUIS AROUND THE WORLD
Central Europe
Pilot study water reuse for a cosmetic company One of the biggest factories of a global cosmetic company is producing hair care, hairstyling and skincare products. In March 2014 they announced their intention to invest in the extension of their facilities with the ambition to reduce the consumption of energy and water, as well as the emission of CO2 of more than 50% within the coming 2 two years.
Germany
New Wastewater Treatment for a dairy factory in Germany A private dairy factory was founded in 1908 and is now one of the largest and most important dairies in Germany. The factory is producing over a million kilograms of milk into high quality milk and cheese specialties. The sustainable and innovative production methods reflect the high quality products they are producing, which are distributed nationally and internationally in 27 countries. The existing on-site wastewater treatment has come through the continuous expansion of production to its limit. Therefore, the dairy factory has decided to build a new WWTP close to the municipal sewage treatment plant, with a capacity of 5,000 m³ / day for treating the dairy wastewater. Nijhuis will supply, install and commission two 40m² flotation units including a flocculator and polymer preparation station. These were assembled in May and commissioned in August 2016. The Nijhuis solution The factory has an on-site 2-mm screening, where the wastewater is mechanically pre-cleaned and then passes into an approximately 1,000 m³ large mixing and equalization tank, where the pH will be adjusted. From there, the wastewater is pumped for 1.5 km to the treatment plant, where flocculation agents will be dosed into the flocculator. The chemically pretreated wastewater will then enter two Nijhuis GDF flotation units. Each flotation has a free water surface of 40 m² and can handle more than 200 m³/hr. After flotation a COD reduction of > 70% is achieved. Solids and lipophilic substances are reduced by > 95%. After pre-treatment, the wastewater will enter biological treatment, which is designed as a SBR plant. Nijhuis Industries NEWS I www.nijhuisindustries.com
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Nijhuis will design a complete state-of-the-art modular treatment solution which will cover the technology and civil works, consisting of filtration, flocculation, flotation, MBR treatment, reverse osmosis and dewatering systems. The customer has chosen Nijhuis because of the pharma and cosmetic references, the highest level of technological support and their application knowledge of the complex scope of turnkey delivery. The customer will recover and reuse 200 m3/d water from app. 300 m3/d wastewater. Currently, a full scale Nijhuis rental plant is in operation to prove the smart and effective design and technology. The rental MBR system has been executed with innovative Nijhuis FLEX-AERATION discs.
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Nijhuis AECOMIX -DGF TM
Turn your wastewater into BIOGAS in one process. Nijhuis Industries NEWS I www.nijhuisindustries.com
Food and beverage production plants are major wastewater contributors and also often have food waste. Particularly plants producing wastewater with a significant total suspended solids and/or fats, oils and grease, like in the dairy, red meat and chicken industry, need to pre-treat their wastewater before high rate anaerobic reactors can be applied. This pre-treatment generally includes undesirable chemical treatment and generates a concentrated side stream which needs to be dealt with.
The AECOMIXTM reactor is an anaerobic reactor with solids retention, particularly suited to treat such effluents, together with available organic wastes. In this manner two waste streams are combined with in one system and a high level of conversion to biogas is achieved. The solids retention is achieved by Dissolved Gas Flotation (DGF).
Full scale reference
A full scale plant AECOMIXTM was installed at a chocolate/ candy factory in the Middle East. The wastewater volume was 100 m3/d, with a COD concentration varying between 20,000 - 60,000 mg/L at an average of 37,000 mg/L. The process comprises the following main components: • • • • •
Equalization tank. 2 AECOMIXTM reactors of 750 m3 each in series with mechanical mixing. Pipe reactor with flocculant dosing. Dissolved Biogas Flotation. Post treatment (Aerobic treatment & Sand Filtration)
Effluent quality
The outlet of the AECOMIXTM-DGF is generally below 1,000 mg/L and varies slightly as a consequence of the high variations in influent concentration. The effluent discharged from the Dissolved Biogas Flotation (DBF) system, is achieving high removal percentages for COD, generally well in excess of 95%. Also, TSS removal in the DGF is on average more than 95%.
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Performance DGF
The flow to the DGF is 5 m3/h. The average MLSS is 6,000 mg/L (6 kg/m3). This means that the solids loading to the DAF are 30 kg/h. The plant operates with 10 l/min gas supply, which equates to 600 l/h and is 9% of the recycle flow. As all, or nearly all, gas will be released as gas bubbles after the pressure is released, the gas to solids ratio can be based on gas supplied divided by amount of solids/h and is 600 L/h / 30 kg/h = 20 L/kg. As we used a gas to solids ratio of 15 L/kg in our design, there is 30% excess gas available. The floating sludge is discharged with a dry solids content, which varies between 5-9% d.m. In order to produce a good performance of the DAF, the dosing of a flocculant is required. The amount of flocculant dosed influences the effluent quality. For optimum performance in the current setup, the dosing is between 3-6 g/kg dry solids.
Why Nijhuis AECOMIXTM?
Several full scale plants have shown the effectiveness and suitability of a Dissolved Gas Flotation device, as a means of solids-liquid separation after a digestion step. • A single step process solution to convert a mix of wastewater and organic wastes in one anaerobic reactor into an energy source. • No pre-treatment required, resulting in lower OPEX. • Highly adaptable to local requirements and conditions. • Simple and stable process. • Use of proven technologies like digestion and dissolved gas flotation.
Read more about AECOMIXTM and the AECOMIXTM paper on our Nijhuis Industries website. Click Here >>
Nijhuis Industries NEWS I www.nijhuisindustries.com
Changing the mindset: Turn flotation fat into BIOFUEL Industrial wastewaters containing oil and grease are often treated by dissolved air flotation (DAF). This treatment results in a sludge with a high fat content. While currently often disposed of, this fat can also be recovered as a valuable product. A laboratory and pilotscale research investigates a novel treatment for fat recovery from chemical-free DAF sludge. At pilot scale 94% of the fat present in DAF sludge was recovered as a fat fraction containing 1.9% w/w water and 0.01% w/w insoluble impurities using the Nijhuis i-FAT system, which uses a special prepared decanter centrifuge to separate heated sludge from a chemical-free DAF unit into three fractions. Application of this i-FAT system on a scale of 2,500 m3/d wastewater, gives a reduction of 21% on total yearly costs.
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Fat recovery can be obtained by heating the dissolved air flotation sludge, followed by separation into a liquid fat, a water and a solids fraction. The objective of this study is to develop a novel treatment for fat recovery of dissolved air flotation sludge. Gravitational settling and centrifugation are investigated as separation techniques and the fat recovery is tested both at laboratory and at pilot scale.
Full-scale study
Why Nijhuis i-FAT?
Economic feasibility of fat recovery
On pilot scale, the use of a three phase decanter centrifuge resulted in up to 94% of the incoming fat being recovered as a 98% w/w fat fraction. Higher purity fat (99.6% w/w) was produced at a recovery rate of 68% using the process configuration decanter centrifuge â&#x20AC;&#x201C; HSS. The decision of which i-FAT process configuration to use is case specific and depends, amongst others, on the desired fat quality.
A full-scale fat recovery process was investigated at a bacon processing factory producing 600 m3/d wastewater, containing 500 mg/L O&G on average. This wastewater was treated by DAF, producing maximal 30 m3/d sludge. Economic potential of fat recovery from DAF sludge was assessed by investigation of the economics of this full-scale fat recovery system. Also, the results of pilot-scale tests were translated to the full-scale business case of applying the system at two different test locations.
A full-scale fat recovery system at a bacon factory confirms the potential of the fat recovery treatment. The installation recovers 6 m3 fat per day on average. Daily, 3 m3 fat is used to feed a steam boiler and supply the entire factory with thermal energy. The quality of the produced fat is also suitable for biodiesel production and therefore, the other 3 m3 fat per day is sold for the production of biodiesel. By calculating the capital expenditures (CAPEX) and operational expenditures (OPEX) for this full-scale fat recovery system, it is determined that the return on investment (ROI) is less than 1.5 years. The costs and benefits of full-scale application of the i-FAT system were estimated. The Nijhuis i-FAT system could simply be put in front of the existing water treatment system. The existing treatment system consists of a DAF unit with chemical use and a series of biological treatments, treating 2,300 m3/d of wastewater.
Separation of fat from chemical-free DAF sludge requires centrifugal forces, since solely gravitational settling does not produce a fraction that consists of predominantly fat.
Full-scale recovery of fat from DAF sludge was shown economically feasible at a bacon factory. The fat quality is suitable to generate biofuel and enables the company to be fully self-sufficient in heating energy. Recovery of fat from wastewater on full scale at a poultry slaughterhouse, would result in an estimated ROI of 1.7 â&#x20AC;&#x201C; 2.0 years with a total yearly costs reduction of 21%. The reduction in total yearly costs is mainly due to a reduction in chemical use, sludge disposal and the revenue from the produced fat.
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Solve high nitrogen issues with Nijhuis Ammonia Recovery High levels of nitrogen give rise to two problems for anaerobic digestion (AD) operators. Firstly, ammonia inhibition can be a major problem during digestion of municipal and industrial sludge. Higher NH3-N concentrations are inhibiting or even toxic for methanogen bacteria, which can cause a decrease in biogas production. Secondly, because of the reduction of COD in anaerobic digestion, the effluent of the anaerobic treatment often results in a COD/Nitrogen ratio which is too low, resulting in the need for additional dosing of a carbon source in the biological nitrogen removal process. The Nijhuis Ammonia Recovery system (NAR) is an innovative process which can solve these issues by removing ammonium from digestate, or other substrate for digestion, and recover ammonium as ammonium sulphate, an agricultural fertilizer. NAR is a robust technology for digestate treatment, with a stable ammonia removal efficiency of 75-90% and competitive to current state of the art ammonia removal technologies.
WHY NIJHUIS AMMONIA RECOVERY?
Results show that stable nitrogen removal rates of more than 80%-90% can be achieved by the NAR system. Ammonium sulphate can be produced at a desirable concentration between 30-40%. The value of ammonium sulphate depends on the produced concentration and local market.
Other significant influences on the cost price per kg N are the scale of the installation, the availability of residual heat and the local value and market potential for ammonium sulphate. The Nijhuis Ammonia Recovery (NAR) system is a highly efficient treatment method to remove and recover ammonium from anaerobic digested manure, municipal and other organic waste waters at NH3-N concentrations above 2 g/L. The NAR system is competitive compared to other new technologies for nitrogen. At influent NH3-N concentrations higher of 2.5 g/L and higher ammonium stripping is highly cost efficient compared to other technologies.
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At concentrations above 2 g/L NH3-N, the NAR technology is cost-effective compared to other forms of nitrogen treatment. The costs per kg N of the NAR system can decrease to 1 â&#x201A;Ź/kg/N at 4 g/L NH3-N.
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