Hot Weather Report

July 29, 2009

Hi, reservoir enthusiasts. Hope you're all having a great summer. 

We're having a great summer here. For us it's great if the phones in customer service are quiet, and so far they have been. A quiet phone means there are no significant water quality problems where our 1700 SolarBees machines are operating!

In wastewater ponds, since every 10c of temperature rise doubles bacterial growth rates, hot weather can really stress the dissolved oxygen and water quality. In a typical unmixed wastewater pond, you will find a hard thermocline at about 1.5 to 2 ft deep. The surface water is hot, with blue green algae out of control, dissolved oxygen at super-saturation to 25 mg/l, and pH often well over 9.0. Underneath that, the water is cool and anoxic and has a much lower pH. If there is flow through the pond, as opposed to a pond being used for storage or irrigation, the flow is usually short circuiting under the warm surface water, and flowing across the bottom of the pond, straight from the inlet to the outlet, without achieving the correct detention time for optimum secondary (BOD, TSS) or tertiary (N, P) treatment. If you mix this pond with a SolarBee, you can reduce or stop the short circuiting, and some of that high oxygen produced at the top can be captured and mixed deeper into the pond to supply the bacteria which clean up the water. Sometimes you can re-set the thermocline to a lower depth, it's easier in May or June than in July, it just depends on sunlight intensity. Also, mixing creates "good" small-celled green edible algae in that top few feet instead of blue-green algae, and then huge daphnia crops appear to eat the algae, all leading to better reduction of BOD and TSS in the pond. In most polishing ponds or effluent storage ponds, water typically enters at 10/10 BOD/TSS, but soon deteriorates, often to 70/140, due to un-checked algae growth, which can lead to discharge permit violations, irrigation system plugging, odor events, and other problems. But with mixing, this deterioration can be eliminated or at least well-controlled.

In most lakes, the hot weather and long days favors blue-green algae blooms, which you can read plenty about on our main website We are having a great summer with our 300+ SolarBee lakes, there have been only a few (less than 10, maybe even less than 5) where there were blue-green algae "pulses" so far, but no full-scale ongoing blooms. People don't buy SolarBees for lakes with great water quality, they buy them for lakes with the worst water quality, so we are pretty happy to have the phone so quiet in the hottest part of the summer!

In potable water reservoirs (chlorinated or chloraminated drinking water tanks, water towers), summer is also the time for many bacterial-based problems. The disinfectant can suddenly disappear when bacterial growth on that tank structure increases with warmer temperatures. The City then has extremely difficult problems. The solution must take into account human health risks if a harmful bacteria gets into the tank, the needs of the community for more water during hot weather, and fire protection issues if it is contemplated to lower or drain the tank to solve the problem. In these tanks, SolarBees keep the water mixed so that bacteria are killed throughout the tank, and so that accurate testing of disinfectant can be conducted. Then, if a water quality problem develops, which is especially common in tanks with long water age, the SolarBee can be used with our chemical injection kit to boost the disinfectant to solve the problem.

To  summarize, summer is time when our machinery and our "theories" get tested the hardest. And so far (knock on wood!), it's been a great summer. Hoping you're having a great one too!