Anammox in active sludge
NAS® (New Activated Sludge) represents a unique active sludge system in which anammox bacteria constitute a part of the biomass. These micro-organisms ensure a very effective removal of the nitrogen during aerobic purification. An aerobic purification step is often necessary to enable the removal of the remaining COD fraction and nutrients and to facilitate effluent re-use.
The NAS® system can be configured with a variety of sludge/water separation systems, e.g. post-settling tanks, flotation or membrane separation. In case an active sludge system or membrane bio reactor (MBR) is configured within a NAS® system a number of additional advantages are obtained, e.g. a significant improved effluent water quality and the option to reduce the dimension of the aerobic purification system.
The NAS® system offers an overall energy gain of about 40-50%. Moreover the installation can be realized in a smaller footprint and there is no need for fresh (COD) supply in support of the denitrification process. At the same time the amount of sludge produced is lower, which results in better economics for the overall operation. The NAS® system is very robust and can therefore be integrated relatively easy in existing active sludge installations. Depending on the needs, the effluent water can be discharged or reused.
Nitrogen removal from ammonia containing water / sludge / digestate and the production of (artificial) fertiliser
During the fermentation of manure and other organic substrates the organic nitrogen present is largely transformed into ammonia (NH4) nitrogen. The high nitrogen content constitutes a limiting factor for field application of the digestate (as a result of European nitrate directive). Current digestate treatment is making use of biological pathways to convert NH4–N into nitrogen gas. These techniques require considerable amounts of energy and result in the loss of nitrogen as nutrient. The AMFER® technology can be applied to produce ammoniumsulphate, which can be used as an (artificial) fertiliser.
Via a batchwise or continuous operation the ammonia is liberated, removed and fixated. For this purpose the digestate is simultaneously heated and aerated. The process is executed at a temperature of around 60°C and there is no need for additional chemicals. The thermal energy required can be obtained form the existing CHP installation.
Phosphate recovery from wastewater
In order to remove phosphates from waste waters or digestate in an environmentally friendly manner, the ANPHOS® process can be applied. During anaerobic waste water purification, the phosphate present is largely converted into ortho-phosphate, whereas the nitrogen is converted into ammonia (NH4-N). In case of aerobic pre-purification orthophosphate is formed as well with potassium as counter-ion.
The basic principle of the ANPHOS® process is the aeration of waste water, which induces a positive pH shift. As a result of the addition of magnesium(hydr)oxide, the ortho-phosphate reacts with ammonia and magnesium ions to form magnesium-ammonium-phosphate (MgAP) or magnesium-potassium-phosphate (MgKP) also known as ‘struvite’ . After the reaction, the struvite is precipitated, dewatered and dried. This product can directly be applied as substitute for agricultural fertilizers. In this manner the phosphate cycle is closed (cradle-to-cradle or C2C). The ANPHOS® process can be applied on all types of waste water with P levels of > 50mg/L.
Reversed osmosis treatment and desalination of waste water
By means of the newly developed RO-Recycle® process it is possible to improve the quality of the effluent of biological water purification systems to fresh water for boiler feed or cooling towers or to process water. This RO (reversed osmosis) technology is capable of processing up to 70% of the total effluent and generate these water qualities. Current state of the art RO systems are capable of phosphate removal such that chemical de-phosphatization steps can be skipped after biological water purification.
In order to obtain the above yields, a special pre-treatment is combined with periodical membrane desinfection and a cleaning regime with standard chemicals. This discipline reduces the cleaning frequency to less than ten times per year and minimizes the operational costs. This process is called : RO-Recycle®.
The remaining 30% of the effluent consists of the more concentrated brine. Before discharging this fraction, a significant part of the salts must be removed. For this purpose a pellet reactor has been developed which allows the removal of more than 80% of the phosphate in the brine, and reduces the content of calcium, magnesium, potassium and sulphate as well. This is achieved by only raising the pH.
These salts are precipitated and harvested in the form of pellets, which after a short draining have a dry weight of more than 90%. The chemical composition of the pellets represents a perfect mix of agricultural nutrients. This proces is called: MemPhos®.
Anaerobic waste water treatment and biogas production
Anaerobic waste water treatment is applied in many industrial areas for waste water purification of water containing large amounts of organics (COD > 2.000 mg/L).
This technique is applied to circumvent the high operational costs of aerobic waste water treatment and to produce energy in the form of biogas. For this purpose a number of UASB reactor types can be used. Additional advantages of this approach are:
Anaerobice waste water treatment is a proces in which bacteria, in the absence of oxygen, convert the organic matter disolved in water into biogas (CH4 and CO2). This proces takes place in a UASB (Upflow Anaerobic Sludge Blanket) reactor. Wastewater is inserted at the bottom of the reactor through a distribution system.
Active biomass for inocculation and kick start UASB
Anaerobic wastewater treatment is frequently applied in a variety of industrial sectors. The granular sludge plays a vital role within this technology. In this way waste water containing levels of organics (COD) is purified effectively. Anaerobic biomass present in the reactor transforms the organic matter into biogas and water. The anaerobic reactors are designed to stimulate the formation of granular sludge, which stays inside the reactor. However, in unfortunate events sludge may wash out from the reactor (e.g. during a calamity). In order to be able to restart the reactor quickly or to startup a fully new reactor, the anaerobic biomass from an existing installation can be used for inocculation purposes.
Colsen has a track record in water purification and energy production for more than 2 decades and counts numerous customers who are operating an anaerobic WWTP. This is the reason why Colsen is able to mediate in the trading of anaerobic granular sludge.
Efficient digestion of organic matter in waste streams
Fermentation represents a natural and anaerobic dissimilation process during which organic biomass is transformed. Certain bacterial strains are capable of converting organic material mainly into methane (CH4), carbon dioxide (CO2) and water. The efficiency of the conversion is determined by the system and the nature of the substrate. This anaerobic digestion process takes place in two different ranges on the temperature scale, i.e. from 30-40°C (mesophilic range) and from 50-55°C (thermophilic range). Thermophilic digestion is often applied for treatment of industrial organic waste products, WWTP-sludges or manure. It is also possible to combine various waste streams, which is then called co-digestion. An additional advantage of thermophilic digestion is that the greater part of pathogens, viruses and germs are pasteurized during digestion at elevated temperature.
25% more COD conversion and up to 50% more biogas from sludge digestion units
The treatment of WWTP sludge represents a considerable cost for a sewage purification plant. In case the sludge amount is lowered the associated costs can be reduced. An efficient way for the reduction of the sludge amount is thermophilic sludge digestion. When compared with conventional mesophilic digestion, thermophilic conditions take care of degradation of an much higher amount of the organic fraction (10-25% more conversion). The (additional) amount of biogas thus produced can be utilised (after S-removal using Bidox®) for the production of electricity and heat using a CHP (combined heat & power) installation. This has a direct positive impact on the energy balance of the sewage purification plant.
Efficient mixing and heating system for digesters
The unique DIGESTMIX® system is capable of mixing and heating the content of a digester at minimum operating (energy and maintenance) costs. This mixing & heating device facilitates a stable temperature, intensive mixing and abatement and prevention of floating layers and scum in the reactor. The DIGESTMIX® can also be delivered in mixing mode only.
This mixing and heating device is situated outside the reactor and allows you to operate a digester without any internal moving parts. Excellent mixing conditions are a prerequisite for a continuous stirred-tank reactor (CSTR) in order to maximize contact of anaerobic bacteria and substrate and to avoid shortcut streams that could result in lower process efficiencies.
In a conventional CSTR the mixing is achieved through biogas injection and/or propellers. In case of the DIGESTMIX® an efficient mechanical mixing is obtained while precluding the formation of scum or foam layers at the surface of the reactor content.
Biological desulphurization of gas streams
One of the most efficient systems for the biological removal of sulphides from biogas is the BIDOX® (BIological Desulphurization by OXidation). No chemicals are needed to operate the BIDOX® system. The installation requires limited maintenance, is equipped with little process control and manages to reduce the amount of H2S in biogas to levels below 50 ppm. These features have a significant positive impact on the life duration and running costs of the CHP engine and efficiently facilitate the upgrade of biogas to natural gas quality.
Biogas desulphurisation using the BIDOX® is not associated with odour emission, because the system is completely closed. In addition there is no need for internal cleaning or biomass discharge.
Balanced broth for optimal microbial activity
Micro-organisms play a key role in nature, and mankind has learned to deploy their enormous variety of biochemical capabilities. Biological process steps have therefore become more and more common in industrial applications. The well-being of the biomass has often become a critical factor in a sequence of process steps. In the last decennia, Colsen has developed a number of biological processes for industrial and communal water purification, for bio-energy production and for biological desulphurization. In order to obtain a “healthy” biomass in large proces installations, a nutrient rich broth was developed, which stimulates bacterial growth and supports the vitality of the biomass.
Over the past years Colsen has developed a broth rich in vital micro-nutrients for the sulfide removal from biogas (BIDOX®). NutriDox® is a non-hazardous nutrient concentrate which can be dosed directly and easily through micro-injection in the process. Feel free to contact us for more information and ordering details.
Treatment method for poultry manure
Colsen has developed a cost effective and sustainable treatment method for poultry manure originating from intensive farming: Poul-AR®.
The Poul-AR® system applies eco-innovative principles and technologies and thus opens a sustainable route to nutrient recovery and energy efficiency for poultry manure. The approach makes use of subsequent biological and physical treatment steps. The 1st step in the process consists of a biological ammonification step in which the manure is liquefied and the organic nitrogen is biologically converted into ammonia. We supply the enzymes to run this process. A 2nd step, the de-ammonification, removes the ammonia present in the broth via stripping with air. The ammonia is subsequently fixated with sulphuric or nitric acid as an ammonium salt (sulphate, nitrate) to produce the desired fertilizer. The residual organic fraction of the manure can now be readily digested to produce biogas which in turn can be used as a source of heat or electricity.