Cactus juice as bioflocculant in the coagulation–flocculation process for industrial wastewater treatment: a comparative study with polyacrylamide

Abstract

Most industries in the world treat their wastewaters with a conventional coagulation-flocculation process using alum as coagulant, polyacrylamide (PAM) as flocculant and lime as coagulant aid. To reduce the use of chemical products in the process, experiments were conducted to substitute the PAM with cactus juice (CJ) as flocculant. From the obtained data, it was concluded that the substitution of PAM with CJ in the coagulation-flocculation process was very effective, compared with PAM. Depending on the wastewater's origin, the bioflocculant showed removal efficiencies of 83.3-88.7% for suspended solids (SS) and 59.1-69.1% for chemical oxygen demand (COD). Lime addition enhanced the coagulation-flocculation process in the presence of CJ similarly to the PAM with efficiencies greater than 90% for both SS and COD. The CJ powder's infrared (IR) spectrum showed the main functional groups present in PAM. It was concluded that CJ as a flocculant fits well with the definition of sustainability and it is appropriate for countries that have regions where cactuses grow naturally.

Plant-Based Tacca leontopetaloides Biopolymer Flocculant (TBPF) Produced High Removal of Turbidity, TSS, and Color for Leachate Treatment

“…A broad peak at 3285 cm −1 was observed, attributed to the absorption of the hydroxyl group (OH) bending to the water molecule. The presence of -COOH, -OH, and -NH 2 functional groups in the polysaccharides-based coagulant made it preferred for aggregation processes [27]. Therefore, all the functional groups observed in Tacca leontopetaloides starch support the capability of starch as the substituted chemical flocculant.…”

Characterization of Two Cactus Formulation-Based Flocculants and Investigation on Their Flocculating Ability for Cationic and Anionic Dyes Removal

“…With similarity to all biological materials derived from plants, cactus extract effectiveness might be affected over time. It is worth noting that Sellami et al [ 30 ] reported that raw juice had lost significantly its flocculation power within seven days once kept at room temperature. Likewise, De Souza et al [ 60 ] noticed that a storage period of four days at room temperature did not affect cactus extracts coagulation activity, however a drastic change occurred starting from the 5th day when a great loss in turbidity removal was registered.…”

“…Effects of storage time on the flocculation performance of the most efficient powder formula were assessed over a period of 8 months. It is worth recalling that the flocculating activity of fresh cactus mucilage is restricted to its shelf life since this material is prone to microbial activity attack due to its considerable water and carbohydrates content [ 30 ]. Hence, producing high quality bio-flocculants with longer longevity is one of the driving forces behind exploring the powdered formulations.…”

“…The grouping of alum and cactus powder is believed to be more effective for contaminants removal compared to their independent use [ 39 ]. Experimental conditions are chosen based on some preliminary tests and on our previous work [ 30 ]. After settling for 30 min, an aliquot of 2 mL from the upper phase of the flocculated solutions was withdrawn for color and turbidity assessment.…”

Health benefits of Cactus

“…In the chemical method the alum is the mostly used coagulant but it has severe health problems like it causes Alzheimer's diseases (Martyn et al, 1989;Letterman and Pero, 1990), so this water cannot be used to irrigate the fields (Aizawa et al, 1990). Cactus can be used as a coagulant (Sellami et al, 2014). Cactus reduces the turbidity, COD, and heavy metal content in water.…”