Frequently Asked Questions

about the Sentinel wastewater treatment system

  • What does the Sentinel treatment system do?

    The system is designed to treat dilute agrochemical waste amongst other contaminants.

    The Sentinel process cleans the water so that the contamination is reduced by over 99.9% to levels where the wastewater can be safely returned to the environment or reused.

  • Can the Sentinel treat wastewater with more than one type of agrochemical contamination?

    Yes. The Sentinel treatment system has been used for treating wide mixture’s of agrochemicals in wastewater throughout the World reducing the agrochemical concentration to below the legal disposal requirements.

    The Sentinel plant is in operation in over 42 countries Worldwide and has been independently tested by over 15 Universities and Governmental authorities. In two Independent tests carried out in the last 12 months the Sentinel plant and process gave outstanding results with over 99.99% reduction of contamination in both cases.

  • Can I treat more than one type of agrochemical in the same Sentinel system?

    Yes. All Sentinels can treat mixed waste streams or batch products.

  • Can the Sentinel treat wastewater from agrochemical manufacturing, blending and packaging?

    Yes. The Sentinel plant is operating in over 100 agrochemical manufacturing, blending, packaging and testing facilities and plants worldwide. The Sentinel plant is operated by many of the worlds major manufacturers as well as many local mixing and blending companies.

  • Are there any independent lab results to prove how effective the Sentinel plant is?

    Yes, you can download our Treatment Performance Data Sheets which offer an indication of treatment quality that may be achieved by the Sentinel process.

  • Why do I need a Sentinel?

    If you are creating pesticide waste from washing your sprayer out and the sprayer vehicle, you need to dispose of the agrochemical waste in an Environment Agency compliant and environmentally acceptable way.
    It is illegal to allow agrochemicals to contaminate and pollute any land and watercourses. There are many rules and regulations regarding the correct usage and handling of agrochemicals and many growers have to adhere to legislation determining how much product can be sprayed onto the crop.

  • How does a Sentinel help me to be legally compliant?

    Even with the best efforts of calculating loads, there is sometimes product left in sprayer tanks that need disposing of. When switching products there is rinsate waste from washing out the sprayer tanks and it’s not always appropriate to travel back out into a field to ‘spray off’. Even with the best spray drift reduction nozzles, every vehicle that is used for spraying will be contaminated on all external surfaces, so any washing of sprayer vehicles will result in wash water that is contaminated with pesticide and as such legally needs collecting and disposing of.
    Using a Sentinel system ensures best practice handling of agrochemicals and pesticide waste disposal treatment, allowing reuse of 96% of the water treated. Having a Sentinel installed can allow for an exemption certificate to be issued by the EA for disposing of the treated waste, giving peace of mind that there will be no hefty fines or disposal fees from a waste contractor.

  • Is the Sentinel compliant?

    The Sentinel has been tested rigorously in the field and by many independent laboratories and government organisations around the world. The Sentinel is Environment Agency and Voluntary Initiative approved as the best practice for waste pesticide treatment and disposal.

  • What kinds of wastewater does the Sentinel plant treat?

    Agrochemical waste consisting of pesticides and/or herbicides primarily from sprayer wash out and sprayer wash down areas. Also from the handling, manufacturing and packaging of agrochemicals.

  • How does the Sentinel plant reduce sprayer washing wastes?

    The Sentinel treats the sprayer washing wastes collected by using a chemical flocculation process that removes the contaminants from the water and concentrates them up into a sludge. For every 1,000 litres treated the Sentinel will return 996 litres of cleaned water for reuse or discharge and 4kg’s of concentrated sludge waste for disposal – effectively reducing the amount of waste to be disposed of by 96%.

  • What do I do with the cleaned water from a Sentinel plant?

    The cleaned water can be reused for vehicle washing, discharged to land or to a drain depending on the site location.
    The treated wastewater can be disposed of over land more than 100 meters from a watercourse or well. In the UK the Environment Agency needs to be informed of your disposal route.
    The treated wastewater can also be disposed to public sewer with a suitable local licence.

  • What about the sludge residue from Sentinel plant?

    The 4% of waste sludge still need to be disposed of to a waste contractor. For larger users, we can reduce the amount of sludge for final disposal if necessary by utilising further technologies.

  • Can the Sentinel treat wastewater with more than one type of pesticide contamination?

    Yes. The Sentinel treatment system has been used for treating wide mixtures of pesticides in wastewater throughout the World and in independent tests, it reduced the concentration of the pesticides to below the legal disposal requirements.

  • Is the Sentinel treatment system reliable?

    Very much so! Agriculturally engineered the Sentinel is a very robust piece of machinery with many units from the 1980’s still in operation today all over the world.

  • What size of Sentinel do I need?

    You need to calculate the amount of wastewater you will create over a day, week and/or a year. You may well produce a large volume one day and very little for the next week. To overcome this you can purchase a large storage tank to store the waste while you are busy and then treat when you are less busy or when the weather is inclement.

  • Does the Sentinel need a lot of time to use?

    The Sentinel comes in a range of automation to suit both the amount of waste to be treated and the amount of time a site has available to operate it. The most basic plant will need one and a half hours of operator input, whereas a full auto needs none.
    Many customers start the process and then go on to other work before returning to the Sentinel plant to finish the process. In all machines, some parts of the process such as filling, emptying through the carbon and pH correction are fully automatic on all machines.

  • Where does the Sentinel plant go?

    The Sentinel is ideally located in the wash down pad area, allowing it to draw directly out of either the wash down pad sump or another collection tank. The treated water can then be stored in the same area and reused to wash down plant/vehicles or to a suitable discharge point into the environment.

  • How do I attach the Sentinel plant to my existing set up?

    Simply position on an existing wash down pad or a flat area nearby and drop the suction hose into the sump or collection tank. Discharge hoses can be connected to a storage tank or run to an appropriate drain/discharge area.

  • Do I need to put the Sentinel inside?

    We would recommend that the Sentinel is undercover and in colder climates, you need to consider the problems caused by freezing temperatures.

  • How much space do I need for the Sentinel plant?

    The Sentinel plants come in a variety of sizes depending on the amount of waste to be treated over the year, but the range starts from a small 1.5-metre square ‘BOX’ and can be as large as needed. Our commonest Sentinel though for most sites is a 200/300 which has a footprint of 3.6m W x 2.1m D x 2.6m H. If you have a particular space in mind or have an unusual requirement, please don’t hesitate to contact us as we are more than used to accommodating tight and odd spaces!

  • Is the Sentinel plant mobile?

    The Sentinel can be mounted onto a trailer for multiple site use. The smallest Sentinel box can be fitted into the back of a pick-up truck. 

    For vineyards that have sumps in individual fields, the Sentinel can be taken to each as is necessary.

  • Who else has Sentinel plant?

    The Sentinel can be mounted onto a trailer for multiple site use. The smallest Sentinel box can be fitted into the back of a pick-up truck. 

    For vineyards that have sumps in individual fields, the Sentinel can be taken to each as is necessary.

  • How long do Sentinel plant last?

    We have Sentinels out in the world that have been operating for close to 30 years and still going strong! Agriculturally engineered to last and work hard, with simple maintenance they can keep going for many years.

  • Is the Sentinel plant easy to look after?

    Yes! No specific knowledge is needed to look after and operate a Sentinel. With very basic training you will be able to treat your waste and carry out simple maintenance tasks to keep your Sentinel running for years.

  • Can I get a grant for Sentinel plant?

    In some areas of the UK, grants may be available – worth checking with your local catchment area farming representative.

Operational Questions

about the Sentinel wastewater treatment system

  • What happens if I put the Sentinel plant treatment chemicals in in the wrong order

    We do not recommend this, but in practice, the incorrect order for dosing of the chemicals will not unduly affect the treatment process.

    In manual plants, the operator has to visibly inspect the quality of the effluent prior to the final stage of carbon adsorption. If the process has not been as efficient due to the incorrect dosing then the tank can be remixed and re-dosed in the correct order.

  • What happens if I add too little treatment chemical to the Sentinel plant

    The recommended weights for the treatment chemicals are drawn up from 20 years of experience throughout the world. If you add too little chemicals you will have to remix and re-dose the waste with the correct weight of treatment chemicals. Re-dosing will not affect the efficiency of the process.

  • What happens if I do not add all the treatment chemicals to the Sentinel plant?

    The process needs the first three chemical agents. If you have forgotten to add one of the agents you can remix the tank and add the forgotten agent.

  • What happens if I have too strong a waste for treatment in the Sentinel plant

    The Sentinel process is not designed to treat concentrated Pesticide product. It has been known for Pesticide concentrate to be thrown into the Sentinel or wastewater storage tank.

    If this has knowingly happened then you should half fill the Sentinel with wastewater and fill to the top with clean water. Treat the resultant mixture as usual.

    If you only find out about the problem after you have carried out the treatment process, drain off half the Sentinel tank back to the storage tank and dilute the rest of the Sentinel tank with water. Remix and treat the waste again. When you next fill the Sentinel plant only half fill the tank and fill the rest of the tank with water. Treat the waste as normal.

  • Can I leave Pesticide waste in the Sentinel tank prior to treatment?

    Yes, you can leave wastewater in the tank for an unlimited time. We recommend that if you leave wastewater for more than 24 hours you mix the tank using the agitator for 5 minutes before adding treatment chemicals.

  • Can I leave settled treated waste in the Sentinel tank?

    We recommend that you only leave the wastewater for 24 hours following treatment prior to discharge.

    If you leave the settled sludge in the bottom of the Sentinel tank for more than 48 hours after draining the clear wastewater through the carbon, in a warm climate the sludge will become concentrated around the drain valve and has been known to block this valve.