An Effective Alternative to CIP Caustic

In a recent trial, numerous process objectives where met when bulk caustic was replaced with a single acid cleaner. The change lowered CIP costs, cut the need for bulk caustic and sulfuric acid, and improved the overall cleanliness of the facility.
By Brian McCluskey | June 11, 2020

Now more than ever, during these uncertain and unprecedented times, ethanol plants are looking for creative solutions to help reduce costs and improve plant performance. One ethanol plant recently boosted its efficiency and efficacy by replacing bulk caustic in its clean-in-place (CIP) process.

Over the past several weeks, economic conditions have forced  ethanol plants to scrutinize operating costs and examine processes. The goals for one recent ethanol plant product trial were straightforward: lower the variable costs of CIP; reduce or eliminate the need for bulk caustic and sulfuric acid; and improve the overall cleanliness of the plant to achieve lower lactic and acetic acid levels in fermentation.

Hydrite Chemical Co. was offered the opportunity to trial Hydri-Maize CRC-152—a single product acid cleaner that simplifies and improves the CIP process—to replace conventional caustic CIP. 

Each of the goals are part of the value proposition that CRC-152 can offer ethanol producers if the material of construction is at least 304 stainless steel. CRC-152 is an effective cleaner because it contains a synergy between being a powerful oxidizer (i.e., its ability to remove organic deposits) and a strong acid (i.e., its ability to remove inorganic scaling). In many cases, inorganic scale such as calcium and magnesium salts, act as a scaffold to allow organic and protein deposits to attach to surfaces. This organic and protein deposit creates a food source for some tenacious biofilm that is difficult to remove. Conventional caustic CIP is not the most effective means to clean these types of deposits, as it merely scours the surface of the biofilm, leaving the rest of the deposit intact. By replacing caustic, we reduce sodium—a known yeast stressor—which helps yeast vitality. It also promotes metabolic activity while lowering bacterial contamination and the cost of antibiotics.

Clear Results, Benefits
As the trial commenced, CRC-152 was batched in the CIP tank containing water at the prescribed amounts in accordance with the procedure Hydrite developed. The dilute CRC-152 solution was used to clean the following unit operations:

• Mash trains/coolers

• Ferm fill header

• Yeast prop

• Fermenters

The Hydrite account manager was on site for the duration of the trial to ensure the sequence started according to the guidelines and instructions provided. Within the first couple days, the customer immediately noticed an increase in lactic and acetic acid levels in fermentation. This was not unexpected as inorganic scale and latent mash containing a high bacterial loading was removed from the system artificially contaminating the downstream fermentation process. To protect fermentation performance, the antibiotic regimen was adjusted accordingly by both type and amount. Further, some potential problem areas were identified that were contributing to the bacterial loading within the plant. These areas included: a leaking valve in the ferm fill header between ferms No. 2 and No. 3; a low spot in the horizontal piping above the mash trains; and low-flow areas in the mash piping because of lower liquefaction pump pressures.

Reviewing these areas of improvement with the customer resulted in good discussion to help improve the efficacy of the cleaning program. It further bolsters the fact that Hydrite is a value-added supplier continually looking for creative solutions to help improve plant performance outside of providing chemicals.

After the first week of running CRC-152, the customer began to see drastic improvements in plant cleanliness. Evidence of this improvement was seen in the CIP tank, as a significant amount of sediment had built up over the previous week and needed to be cleaned out. Improved plant cleanliness translated directly to reduced lactic and acetic acid levels in fermentation to near baseline levels. The antibiotic demand also dropped as expected. After two to three weeks, plant metrics continued to improve with the key performance indicators (KPI’s) of lactic/acetic acid levels and antibiotic demand dropping to below baseline levels. Averaging lactic and acetic acid levels over eight fermenters showed at least a 40% reduction when comparing the current operation to the baseline data at both 10-hour ferm samples and ferm drop. At this point, the plant had become comfortable using CRC-152 as a replacement for caustic in its CIP program.

CRC-152 is an excellent option for plants looking to improve the efficiency and efficacy of their CIP program. Hydrite provides a very effective product along with the necessary experience to assist producers with the product conversion. The experiences from this case study and others help to clearly define the goals and objectives to minimize risk and maximize the value proposition. As it relates to the original goals of this customer, Hydrite delivered:

1. Lowered variable cost

• Net savings over $180,000 per year

• Antibiotic demand reduced from 4.5 pounds per ferm to 2.5
pounds per ferm (a 44% reduction)

2. Reduced/eliminated the need for bulk caustic and sulfuric acid

• CRC-152 is a direct replacement for caustic in CIP

• Removing caustic reduces plant alkalinity, which reduces the
need for bulk sulfuric acid to pH adjust front-end process

• Eliminated two bulk chemicals to help improve plant safety
and operational stability

3. Improved overall plant cleanliness to reduce lactic and acetic
acid levels in fermentation

• Lactic and acetic acid levels were reduced at least 40% when
compared to baseline data

• Overall plant cleanliness was significantly improved

Moving forward, Hydrite has a plan to counteract the effects from the initial burst of bacterial loading after starting the CRC-152. Given the chemical nature of CRC-152, it is expected that biofilm and inorganic scale will be removed after the initial startup. This impact could carry through to fermentation if not treated correctly. The future strategy is to include Hydri-Maize 2759 as part of the program to help reduce any negative impacts on fermentation. Hydri-Maize 2759 is a GRAS-approved antimicrobial that contains peracetic acid. In tandem with CRC-152, Hydri-maize 2759 will be used as a fermentation pretreatment to minimize any detrimental effects as the system is cleaned.

Author: Brian McCluskey
Biofuels Sales Manager
Hydrite Chemical Co.