Page 19 - Australian Pork Newspaper

Food processing company gets amazing results with venturi-aerator
IN 2018, Bega Cheese Northern Victoria envi- ronmental manager Mr Sean Trebley was given the task of upgrading the Strathmerton Plant’s wastewater aeration sys- tem.
The wastewater system consisted of a DAF unit, which flowed into an aer- ated lagoon, and after this the effluent was stored in two non-aerated lagoons during winter before ir- rigation in summer.
Aerators are needed to keep the COD down and reduce odours in the aer- ated and downstream non- aerated lagoons.
They had an ageing sys- tem of surface aerators in the aerated lagoon, con- sisting of two 22kW units and six 8kW units, how- ever, generally only one or two of these units was operated at any time.
Over a number of years these surface aerators had progressively failed because of their age and repairing them meant deploying cranes and/or boats to access them.
This process was expen- sive and had resulted in damage to the dam liner.
Eventually it became uneconomical to keep re- pairing the aerators.
Therefore it was decided
to look for a solution that was safer for operators and easier to maintain.
Mr Trebley contacted Hydro Innovations to discuss the use of their ‘bank-mounted’ venturi- aeration systems.
These are mounted on the banks of lagoons and use a self-priming pump to draw water from the lagoon.
The pump discharges it under pressure through the venturi-aerator.
The unit draws in atmos- pheric air using the ‘ven- turi effect’, mixes it with the water being pumped and discharges it back into the lagoon, charged with dissolved oxygen.
Sean and his team re- ally liked the idea of bank mounting because it gave operators easy access to equipment for monitoring and/or repair, making it much safer and more cost effective to maintain.
Their only concern was whether the units were as efficient as the surface- mounted technologies.
Hydro Innovations was able to provide informa- tion indicating that with the use of the right pump, oxygen transfer efficiency for venturi-aeration units can be as high or high- er than 1.86kgO2/kWh,
making them at least as efficient as the surface (floating) technologies.
The aerated lagoon con- tained 45ML of effluent, with in-flows from 80- 120ML per year.
This required a 150mm venturi-aeration unit and was paired with a Gor- man-Rupp V6A60-B self- priming pump, with a hy- draulic efficiency of 70 percent.
Bega installed the unit early in 2019.
The attached photo shows the condition of the lagoon at this point, after the previous system had been decommissioned several months previous.
In this photo you can see ripples from the aerator ‘radiate’ to all parts of the lagoon, ensuring a good level of mixing.
Since installation, op-
erators have seen a con- tinued increase in the dis- solved oxygen level and have seen COD fall by 50 percent, even though the higher level of mixing was re-suspending set- tled solids, which became more ‘bioavailable’ to the CFUs.
Sean and the Bega crew are happy with the ever- increasing levels of DO, the reduction in COD and the odour-free lagoon.
The wastewater and maintenance teams are al- so pleased that monitoring and maintenance can be done safely, and without the use of cranes, boats or winches.
More information about venturi-aerators and Gor- man-Rupp pumps can be obtained from info@hy droinnovations.com.au
Prior to the installation.
Two weeks after the new system was installed.
Bega Strathmerton’s new venturi-aerator system.
Thailand designates
24 surveillance areas
for swine fever
THAILAND has des- ignated 24 provinces as ‘surveillance areas’ for African swine fever and ordered strict animal controls in the hope of preventing an outbreak of the deadly disease that has hit its neighbours.
Thailand has been on high alert since the out- break of African swine fever among pigs in My- anmar, Laos and Cambo- dia, but it has yet to report an outbreak.
Earlier in September, the government ordered the culling of 200 pigs as pre- ventative action after two pigs died mysteriously in the northern province of Chiang Rai, 20km from the Myanmar border.
Those two pigs turned out not to be infected, an agriculture official said.
The government has put 24 of its 77 provinces on watch, with restrictions on movement of pigs and wild boars as well as car- casses, semen or embryos for breeding.
Violation of the restric- tions is punishable by im- prisonment of up to two years and a fine of up to 40,000 baht ($A1930).
Department of Live- stock Development di- rector-general Sorawit www.porknews.com.au
Thaneto said, “This is a precautionary measure for provinces that have large pig populations or are in border areas.”
“The results of the blood test from pigs culled in Chiang Rai also show the pigs were not infected, but we continue to be on alert.”
Private business mem- bers of the Swine Raisers Association of Thailand have also jointly bought 8000 pigs raised in ‘risk areas’ along the border to limit exposure to the dis- ease in future stocks.
Those pigs were not infected and have since been slaughtered and sold as meat.
Deputy Agriculture Minister Prapat Pothasu- thon said: “I want to stress that there is no outbreak of the disease in Thailand and both government and private sectors are work- ing together to prevent this.”
ASF was first detected in Asia in August 2018 in China, wiping out nearly 40 percent of pigs in the world’s largest pork pro- ducer.
It has since spread across Asia, affecting Mongo- lia, Vietnam, Cambodia, Laos, Myanmar and the Philippines.
Australian Pork Newspaper, October 2019 – Page 19