Smart Flocculator for Washing Machines

What it does

Smart Flocculator efficiently traps surfactant waste from washing machine discharge with Bentonite clay stirrers to supply low chemical water for residential grey water reuse. Said Benonite clay surface is modified and turns into adsorbent for oily wastewater.

Your inspiration

Given the high proliferation of washing machines in households and that production of common surfactants reaches billions of kilograms annually, there is an increasing need for a novel methodology to process surfactant discharges. On the other hand, BTEX (Benzene, Toluene, Ethyl-benzene, Xylene) contamination in water is prevalent in sites dealing with gasoline or other petroleum-related products. BTEX are carcinogenic volatile organic compounds that directly attacks the central nervous system when exposed to. After comparing molecular geometry and interacting forces, I discovered that surfactant waste can be used to adsorb and remove BTEX.

How it works

Having a porous nature and a high surface area, Bentonite has favourable properties for adsorption. Thus, it can be used to remove surfactants from wastewater through flocculation: hydrophobic surfactant head first substitutes the inorganic (Sodium) cations at the exchangeable sites of raw Bentonite, and then expose its organo-philic tail outwards to adsorb VOCs by partition. Miniature versions of the flocculation stirrers is made into add-on cartridges and mounted onto domestic washing machines, to generate modified Bentonite from capturing grey water discharge before treating oily wastewater. Also, Smart Flocculator doubles as a device that isolates and filters off surfactants from grey water. Thus, it serves a secondary function of supplying chemical-free water for residential grey water use such as flushing pavements or toilet bowls. Concretely, an efficient reuse of grey water to generate spent bentonite and subsequently used as water for flushing.

Design process

The feasibility of Bentonite to be used in an adsorption based treatment methodology of both surfactants and VOCs has been found to be favourable via Langmuir, Freundlich, and BET analysis. The theoretical feasibility of the adsorption mechanism has also been verified by a government laboratory working on innovations in water technologies. The next challenge is then to match surfactant concentration in domestic grey water to the higher levels required to optimize the generation of spent bentonite. A typical washing machine’s discharge can be broken down into the mixture of grey water generated by the various wash programs set by the user. Generally, said programs automate a sequence of soak, wash, rinse, and spin cycles. Since surfactants are mainly involved in the “wash” cycle, discharge of the remaining cycles only seeks to dilute the surfactant concentration of grey water produced by the washing machine. The “Smart” feature of the flocculator is thus added to “learn” the various discharges of the washing machine: First, by user supervision and input of commonly used wash programs; and ultimately, by a combination of timer and discharge volume sensors for a Naïve Bayes machine learning algorithm approach. A working prototype is currently in progress in the college workshop.

How it is different

My project aims to turn the waste of one industry into the resource of another and is the only solution that utilises such a 2-in-1 waste removal technology. Current treatment methods for oily wastewater include carbon filters treated with synthesized chemicals containing quaternary alkylammonium cations that are not only costly but could also ironically cause pollution themselves. Since the current infrastructure of treating VOC waste employs the use of surface modified clay, the concept of surfactant modified Bentonite will be met with lesser resistance as only the surface modifying agent is replaced. Smart Flocculator is also unusual in that it leverages on the collective effort of domestic households to upscale the production of modified Bentonite.

Future plans

I aim to reiterate the prototype design to keep manufacturing cost and complexity to a minimum, making them affordable for households. Looking forward, I envision a grey water reuse platform with a cartridge exchange framework whereby “spent” cartridges from the smart flocculator are collected to treat VOC waste and recycled via anaerobic sludge blanket digester techniques. Recognition programs under the exchange framework would then provide extrinsic motivation for households to adopt Smart Flocculator - ensuring a sustainable water supply by promoting the reuse of grey water and targeting common wastewater pollutants.

Awards

Theoretical and feasibility study of the design won merit in several competitions: Singapore Science and Engineering Fair, Singapore Junior Water Prize, A*STAR Talent Search, and the OCPA-APS Outstanding Conference Poster Awards.