How To Maintain Alkalinity In Wastewater

Industrial and municipal wastewater needs to be treated before it enters water bodies, such as lakes, canals and rivers. Extreme pH levels, toxic contaminants like arsenic and high levels of alkalinity are common problems in wastewater. Alkalinity in wastewater is due to the presence of dissolved mineral salts, including sulfates, carbonates and bicarbonates. High levels of alkalinity can cause problems, such as large amounts of scale and sludge, overheating heat exchangers and pipeline clogs. In most of these cases, high alkalinity is the problem rather than low alkalinity.

Step 1

Purchase an alkalinity test kit, along with sodium bisulfate, muriatic acid and sodium bicarbonate, from a chemical store or a pool supply retailer.

Step 2

Measure the alkalinity of the wastewater with the test kit. Read the instructions provided with the kit for use. Take a sample (100 ml) of the wastewater from the primary storage area, such as the storage pit, storage tank or lagoon.

Step 3

Add sodium bisulfate and muriatic acid to lower the alkalinity of the wastewater. High alkalinity levels for domestic wastewater are 200 ppm and above. For industrial wastewater, these levels are very high. For example, high alkalinity levels can reach a figure of 500 ppm or more in the beverage industry.

Step 4

Use sodium bicarbonate to increase the alkalinity of the wastewater. A low alkalinity range is between 50 ppm to 100 ppm for domestic wastewater. For industrial wastewater, the alkalinity levels are much higher and specific to each industry. For example, the beverage industry can have a low alkalinity level of 200 to 230 ppm.

Step 5

Add the chemicals in a progressive manner and repeatedly check the alkalinity value. To 10,000 gallons of wastewater, add 1.6 pounds of sodium bisulfate to decrease the alkalinity by 10 ppm and add 1.5 pounds of sodium bicarbonate to increase the alkalinity by 10 ppm.