People served in the cities of Lahti and Hollola
MEUR revenue in 2016
m3 drinking water produced daily
m3 wastewater processed daily
Lahti Aqua Ltd provides drinking water and wastewater services for the cities of Lahti and Hollola in southern Finland. The customers it serves are lucky to be able to take advantage of Finland’s famously clean, high-quality groundwater, and Lahti Aqua is focused on making sure this valuable asset gets the treatment it deserves. In fact, the groundwater in the land of a thousand lakes is so pure you could drink it without any treatment; however, to keep bacteria at bay in the distribution network the water is treated with chloramine and UV light.
Wastewater is treated mechanically, biologically, and chemically to ensure it meets the very high standards set by the local environmental authorities. Organic matter and nitrogen are removed by biological treatment, while phosphorus is removed from the water using chemicals.
Where there’s water treatment, there’s sludge. Wastewater from households and other sources is treated to remove contaminants, with the end results being treated effluent – which can be safely discharged into rivers or lakes – and sewage sludge. It’s pretty simple really: the more water you treat, the more sludge you have to deal with. Disposal of this sludge comes at a price, so anything you can do to reduce its volume pays off, financially and environmentally. This is where dewatering comes in, and where the story of the relationship between Lahti Aqua and Kemira begins.
Lahti Aqua was already actively investigating how it could cut its sludge disposal costs while also improving the performance of its sludge dewatering operations – the process used to reduce sludge volumes by removing as much of the water content as possible. They had also been looking into how the latest on-line measurement technologies could support their efforts. Enter Kemira KemConnect SD – a one-of-a-kind performance-based solution that would help Lahti Aqua take sludge dewatering performance to a whole new level.
“We had already been discussing internally about what we could do to cut sludge disposal costs and what new technologies could help us, so when Kemira approached us with this unique solution we were very interested in what they had to say,” says Janne Mäki-Petäjä from Lahti Aqua.
The new solution was KemConnect SD, where the SD stands for smart dewatering. Based on Kemira’s industry-leading expertise and technologies, the service optimizes the chemical sludge treatment prior to dewatering, according to the customer’s unique process conditions. What sets KemConnect SD apart is that it is based on jointly agreed performance targets.
KemConnect SD is a remote service that uses real-time analytics and an advanced dosage control algorithm to enable automated and optimized application of sludge treatment chemicals prior to dewatering. Continuous dosage optimization maximizes the performance of the sludge dewatering process, even under changing process conditions. The service includes chemical products and chemical expertise, on-line measurement sensors, and recommendations on optimal dosing points, as well as a customized reporting system.
The setup at Lahti Aqua comprises a KemConnect SD control unit to control polymer dosing based on the Kemira algorithm as well as sensors installed at various points of the process to gather data: a sensor to measure inlet dry solids in both centrifuges, a sensor to measure suspended solids in the reject water, and a sensor to measure the dry solids content of the sludge.
“What really attracted us was the performance-based model. It means we (Lahti Aqua and Kemira) are both on the same side of the table because it’s a win-win situation: when the sludge is drier we win because our disposal costs are lower, and of course Kemira wins because they are hitting or even exceeding the agreed targets,” says Janne Mäki-Petäjä.
“With KemConnect SD, Lahti Aqua is benefiting from far more than just our chemical products; it’s the combination of our chemical expertise, application know-how, integrated algorithm, and deep knowledge of their processes that is helping them take things to a whole new level,” says Toni Kettunen from Kemira.
increase in dry solids
average reduction in suspended solids in reject water
reduction in monthly disposal costs
Although Lahti Aqua only began using the KemConnect SD service in May 2018, the results so far have been highly impressive. Not only have the dry solids levels of the dewatered sludge increased by 4%, meaning less volume to dispose of, but the suspended solids in the reject water have fallen too, down to 500 mg/l. This is important because the better the quality of the reject water, the lower the volume that needs to be returned to the plant for further treatment. When it comes to the bottom line, the KemConnect SD service has delivered a monthly saving in sludge disposal costs of over €4,000 for Lahti Aqua.
The four new on-line sensors provided as part of the package also enable much more accurate control over the wastewater treatment process. Using the KemConnect platform, all relevant performance parameters at the plant can be monitored in real time, providing both Lahti Aqua and Kemira’s team of experts with valuable information for application optimization and remote performance control.
“The KemConnect SD service is delivering highly impressive results so far, and there’s no reason why we shouldn’t expect that trend to continue. Far more than merely cutting our disposal costs, the service has allowed us to optimize the whole sludge management process, and we’ve been very satisfied with the expert support that the Kemira team has provided,” says Janne Mäki-Petäjä. “With results this impressive in just a few months, we’re excited to see where we can take things from here.”